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Eloïse Ashworth
Key words Five species, somatic and otolith growth, coupling, environmental variables, implications for sclerochronology. Abstract Sclerochronology in fishes has focused the relationships of the distances between the annually-formed zones in otoliths and certain environmental variables. The results have frequently been used as a proxy for the relationship between somatic growth and those environmental variables. Yet, as somatic and otolith growth may be partially uncoupled, inter-annual variations in the increment widths in otoliths may not fully reflect the trends in somatic growth. Thus, for sclerochronological studies on a species, it is important to determine the precise relationship between otolith and somatic growth. This study has elucidated the extent to which variations in otolith and somatic growth are related in fish of the same age, by deriving the otolith sizes and length (TL) at age at capture for six species whose environments, i.e. marine vs estuarine and tropical vs temperate, and life cycle characteristics, i.e. gonochoristic vs hermaphroditic, differ and, for one species (Acanthopagrus butcheri), different periods and estuaries. A sagittal otolith from each fish was sectioned and the distance from its primordium to the outer edge of the otolith measured to 1 m along an axis adjacent to the sulcus and perpendicular to the growth zones. The Schnute, rather than the von Bertalanffy growth curve, typically provided a better fit to both the TL and otolith size at age and was thus used for analyses. Growth curves were fitted simultaneously to somatic and otolith data. The deviations from these curves, which were assumed to have a bivariate normal distribution, were positively correlated and differed significantly from zero. Thus, for fish of a given age in a given habitat, the rates of somatic and otolith growth are linearly related. Variations in otolith growth, resulting from environmental change, unless markedly outside the range of the data, thus result in a predictable level of change in somatic growth.
Murdoch University

90 South Street

​Murdoch, Western Australia

6150Australia+61 (0)4 14 74 54 28E.Ashworth@murdoch.edu.auPresentationAre relationships between fish length and otolith radius enhanced by accounting for correlated errors? Implications for back-calculation.
  
Eloïse Ashworth
Title: Are relationships between fish length and otolith radius enhanced by accounting for correlated errors? Implications for back-calculation. Author: Eloïse Ashworth, PhD candidate, E.Ashworth@murdoch.edu.au, Centre for Fish and Fisheries Research, Murdoch University, South Street, WA 6150, Australia. Co-authors: Professor Ian Potter, Professor Norm Hall and Dr. Peter Coulson, Centre for Fish and Fisheries Research, Murdoch University, South Street, Western Australia 6150, Australia. Dr. Alex Hesp, Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries, Post Office Box 20, North Beach, Western Australia 6920, Australia. Key words Five species, somatic and otolith growth, coupling, environmental variables, implications for sclerochronology. Abstract Sclerochronology in fishes has focused the relationships of the distances between the annually-formed zones in otoliths and certain environmental variables. The results have frequently been used as a proxy for the relationship between somatic growth and those environmental variables. Yet, as somatic and otolith growth may be partially uncoupled, inter-annual variations in the increment widths in otoliths may not fully reflect the trends in somatic growth. Thus, for sclerochronological studies on a species, it is important to determine the precise relationship between otolith and somatic growth. This study has elucidated the extent to which variations in otolith and somatic growth are related in fish of the same age, by deriving the otolith sizes and length (TL) at age at capture for six species whose environments, i.e. marine vs estuarine and tropical vs temperate, and life cycle characteristics, i.e. gonochoristic vs hermaphroditic, differ and, for one species (Acanthopagrus butcheri), different periods and estuaries. A sagittal otolith from each fish was sectioned and the distance from its primordium to the outer edge of the otolith measured to 1 m along an axis adjacent to the sulcus and perpendicular to the growth zones. The Schnute, rather than the von Bertalanffy growth curve, typically provided a better fit to both the TL and otolith size at age and was thus used for analyses. Growth curves were fitted simultaneously to somatic and otolith data. The deviations from these curves, which were assumed to have a bivariate normal distribution, were positively correlated and differed significantly from zero. Thus, for fish of a given age in a given habitat, the rates of somatic and otolith growth are linearly related. Variations in otolith growth, resulting from environmental change, unless markedly outside the range of the data, thus result in a predictable level of change in somatic growth.
Murdoch University

​9 Stirling Street

​Femantle

6160Australia+61 (0)4 14 74 54 28E.Ashworth@murdoch.edu.auPresentationAre relationships between fish length and otolith radius enhanced by accounting for correlated errors? Implications for back-calculation.
  
Eloïse Ashworth
Title: Are relationships between fish length and otolith radius enhanced by accounting for correlated errors? Implications for back-calculation. Author: Eloïse Ashworth, PhD candidate, E.Ashworth@murdoch.edu.au, Centre for Fish and Fisheries Research, Murdoch University, South Street, WA 6150, Australia. Co-authors: Professor Ian Potter, Professor Norm Hall and Dr. Peter Coulson, Centre for Fish and Fisheries Research, Murdoch University, South Street, Western Australia 6150, Australia. Dr. Alex Hesp, Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries, Post Office Box 20, North Beach, Western Australia 6920, Australia. Key words Five species, somatic and otolith growth, coupling, environmental variables, implications for sclerochronology. Abstract Sclerochronology in fishes has focused the relationships of the distances between the annually-formed zones in otoliths and certain environmental variables. The results have frequently been used as a proxy for the relationship between somatic growth and those environmental variables. Yet, as somatic and otolith growth may be partially uncoupled, inter-annual variations in the increment widths in otoliths may not fully reflect the trends in somatic growth. Thus, for sclerochronological studies on a species, it is important to determine the precise relationship between otolith and somatic growth. This study has elucidated the extent to which variations in otolith and somatic growth are related in fish of the same age, by deriving the otolith sizes and length (TL) at age at capture for six species whose environments, i.e. marine vs estuarine and tropical vs temperate, and life cycle characteristics, i.e. gonochoristic vs hermaphroditic, differ and, for one species (Acanthopagrus butcheri), different periods and estuaries. A sagittal otolith from each fish was sectioned and the distance from its primordium to the outer edge of the otolith measured to 1 m along an axis adjacent to the sulcus and perpendicular to the growth zones. The Schnute, rather than the von Bertalanffy growth curve, typically provided a better fit to both the TL and otolith size at age and was thus used for analyses. Growth curves were fitted simultaneously to somatic and otolith data. The deviations from these curves, which were assumed to have a bivariate normal distribution, were positively correlated and differed significantly from zero. Thus, for fish of a given age in a given habitat, the rates of somatic and otolith growth are linearly related. Variations in otolith growth, resulting from environmental change, unless markedly outside the range of the data, thus result in a predictable level of change in somatic growth.
Murdoch University
6160Australia+61 (0)4 14 74 54 28E.Ashworth@murdoch.edu.auPresentationAre relationships between fish length and otolith radius enhanced by accounting for correlated errors? Implications for back-calculation.
  
EloiseAshworth
Sclerochronology in fishes has focused the relationships of the distances between the annually-formed zones in otoliths and certain environmental variables. The results have frequently been used as a proxy for the relationship between somatic growth and those environmental variables. Yet, as somatic and otolith growth may be partially uncoupled, inter-annual variations in the increment widths in otoliths may not fully reflect the trends in somatic growth.  Thus, for sclerochronological studies on a species, it is important to determine the precise relationship between otolith and somatic growth.
This study has elucidated the extent to which variations in otolith and somatic growth are related in fish of the same age, by deriving the otolith sizes and length (TL) at age at capture for six species whose environments, i.e. marine vs estuarine and tropical vs temperate, and life cycle characteristics, i.e. gonochoristic vs hermaphroditic, differ and, for one species (Acanthopagrus butcheri), different periods and estuaries.
A sagittal otolith from each fish was sectioned and the distance from its primordium to the outer edge of the otolith measured to 1 m along an axis adjacent to the sulcus and perpendicular to the growth zones. The Schnute, rather than the von Bertalanffy growth curve, typically provided a better fit to both the TL and otolith size at age and was thus used for analyses. Growth curves were fitted simultaneously to somatic and otolith data. The deviations from these curves, which were assumed to have a bivariate normal distribution, were positively correlated and differed significantly from zero. Thus, for fish of a given age in a given habitat, the rates of somatic and otolith growth are linearly related. Variations in otolith growth, resulting from environmental change, unless markedly outside the range of the data, thus result in a predictable level of change in somatic growth.
Centre for Fish and Fisheries Research, Murdoch University,

​South Street,

​WA 

6150,AustraliaE.Ashworth@murdoch.edu.auWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPresentationAre relationships between fish length and otolith radius enhanced by accounting for correlated errors? Implications for back-calculation
  
BenjaminWalther
Artificial chemical marking of calcified structures, such as otoliths, has emerged as a powerful method to assess stocking success and determine connectivity patterns in fresh and marine systems. Although transgenerational and larval immersion methods have been validated, dietary transmission of enriched stable isotopes to calcified structures would allow minimal handling of animals and reduced expense for flow-through systems. A series of experiments were conducted to validate the feasibility of this method. First, we experimentally manipulated 137Ba in diets and successfully marked otoliths in red drum Sciaenops ocellatus larvae, fingerlings and sub-adults as well as fin rays and scales of sub-adults. After two weeks, marking success of otoliths was 100% for larvae and fingerlings reared at higher temperatures, indicating the need for sufficient growth to occur for consistently detectable marks. Spiked Ba successfully marked fin rays (86% marked) and scales (100% marked) of sub-adults, providing a cost-effective method for marking structures that can be sampled non-lethally. Second, we manipulated both 138Ba and 86Sr in diets over four weeks and evaluated uptake of each isotope spike into otoliths. Otoliths were successfully marked with Ba isotopes and stabilized after two weeks of exposure, whereas dietary transmission of the Sr isotope spike was not successful. We used a concentration-dependent mixing model to explore the potential influence of relative differences in water and dietary elemental concentration to explain differential marking success of Ba and Sr in marine systems. This mixing model will be useful for future workers to estimate the feasibility of dietary spiking in various systems with divergent water chemistry. Where feasible, dietary marking of calcified structures may be the method of choice where handling must be minimized or water chemistry cannot be manipulated.
University of Texas

750 Channel View Drive​

​Port Aransas, Texas

78373USAbwalther@utexas.eduTheme III: Population indicatorsPresentationDietary transmission of isotope spikes to otoliths, fin rays and scales: experimental validation and concentration-dependent mixing models
  
BenjaminWalther
Artificial chemical marking of calcified structures, such as otoliths, has emerged as a powerful method to assess stocking success and determine connectivity patterns in fresh and marine systems. Although transgenerational and larval immersion methods have been validated, dietary transmission of enriched stable isotopes to calcified structures would allow minimal handling of animals and reduced expense for flow-through systems. A series of experiments were conducted to validate the feasibility of this method. First, we experimentally manipulated 137Ba in diets and successfully marked otoliths in red drum Sciaenops ocellatus larvae, fingerlings and sub-adults as well as fin rays and scales of sub-adults. After two weeks, marking success of otoliths was 100% for larvae and fingerlings reared at higher temperatures, indicating the need for sufficient growth to occur for consistently detectable marks. Spiked Ba successfully marked fin rays (86% marked) and scales (100% marked) of sub-adults, providing a cost-effective method for marking structures that can be sampled non-lethally. Second, we manipulated both 138Ba and 86Sr in diets over four weeks and evaluated uptake of each isotope spike into otoliths. Otoliths were successfully marked with Ba isotopes and stabilized after two weeks of exposure, whereas dietary transmission of the Sr isotope spike was not successful. We used a concentration-dependent mixing model to explore the potential influence of relative differences in water and dietary elemental concentration to explain differential marking success of Ba and Sr in marine systems. This mixing model will be useful for future workers to estimate the feasibility of dietary spiking in various systems with divergent water chemistry. Where feasible, dietary marking of calcified structures may be the method of choice where handling must be minimized or water chemistry cannot be manipulated.
University of Texas
78373USAbwalther@utexas.eduTheme III: Population indicatorsPresentationDietary transmission of isotope spikes to otoliths, fin rays and scales: experimental validation and concentration-dependent mixing models
  
Quang MinhDinh
Age structure of the goby Parapocryptes serperaster in the Mekong Delta, Vietnam, based on length-frequency and otolith analyses Quang Minh Dinh1,2,*, Jian G. Qin1, Sabine Dittmann1 and Dinh Dac Tran3 1 School of Biological Sciences, Flinders University, Australia 2 School of Education, Can Tho University, Vietnam * Email: quang.dinh@flinders.edu.au or dmquang@ctu.edu.vn 3 College of Aquaculture and Fisheries, Can Tho University, Vietnam Age structure of the goby Parapocryptes serperaster was determined by analysing length-frequency distributions and examining the sagittal otolith in fish sampled from March 2013 to February 2014 in the Mekong Delta, Vietnam. A total of 476 individuals (246 males and 239 females) were collected in the study site in wet and dry seasons. The total lengths were 107 - 221 mm for female and 121 - 230 mm for male. Otoliths from 164 female and 196 male gobies were readable, and the average percent error (IAPE) of three reading times was 4.65%. Otolith length, width and weight were determined and the use of morphometric analyses for age identification was evaluated. Morphometric data from the otoliths had a strong relationship with fish length of the two genders. The maximum age was 3.93 years for males and 3.77 years for females. The mean age estimated by reading otolith annual rings and by analysing length frequency distribution was not significantly different, suggesting that both otolith weight and morphometrical dimension can be used as a predictor for fish age identification. The most accurate age identification can be made by measuring otolith length, followed by otolith mass and otolith width. Key word: Parapcryptes serperaster, otolith, age structure, Vietnam
School of Biological Sciences, Flinders University, Australia; School of Education, Can Tho University, Vietnam

School of Biological Sciences, Flinders University, Australia, SA5042

​Adelaide, South Australia

SA5042Australiaquang.dinh@flinders.edu.au or dmquang@ctu.edu.vnTheme I: Environmental indicatorsPresentationAge structure of the goby Parapocryptes serperaster in the Mekong Delta, Vietnam, based on length-frequency and otolith analyses

Parapcryptes serperaster, otolith, age structure, Vietnam

  
BenjaminWalther
Artificial chemical marking of calcified structures, such as otoliths, has emerged as a powerful method to assess stocking success and determine connectivity patterns in fresh and marine systems. Although transgenerational and larval immersion methods have been validated, dietary transmission of enriched stable isotopes to calcified structures would allow minimal handling of animals and reduced expense for flow-through systems. A series of experiments were conducted to validate the feasibility of this method. First, we experimentally manipulated 137Ba in diets and successfully marked otoliths in red drum Sciaenops ocellatus larvae, fingerlings and sub-adults as well as fin rays and scales of sub-adults. After two weeks, marking success of otoliths was 100% for larvae and fingerlings reared at higher temperatures, indicating the need for sufficient growth to occur for consistently detectable marks. Spiked Ba successfully marked fin rays (86% marked) and scales (100% marked) of sub-adults, providing a cost-effective method for marking structures that can be sampled non-lethally. Second, we manipulated both 138Ba and 86Sr in diets over four weeks and evaluated uptake of each isotope spike into otoliths. Otoliths were successfully marked with Ba isotopes and stabilized after two weeks of exposure, whereas dietary transmission of the Sr isotope spike was not successful. We used a concentration-dependent mixing model to explore the potential influence of relative differences in water and dietary elemental concentration to explain differential marking success of Ba and Sr in marine systems. This mixing model will be useful for future workers to estimate the feasibility of dietary spiking in various systems with divergent water chemistry. Where feasible, dietary marking of calcified structures may be the method of choice where handling must be minimized or water chemistry cannot be manipulated.
University of Texas

​750 Channel View Drive

Port Aransas, Texas​

78373USA361-749-6810bwalther@utexas.eduTheme III: Population indicatorsPresentationDietary transmission of isotope spikes to otoliths, fin rays and scales: experimental validation and concentration-dependent mixing models

​isotope marking, diet, fin rays, scales, barium, strontium

  
sakina jaafourAhmed YAHYAOUI,Rachid AMARA, Khalef RABHI; Abderrahim SADAK
Coastal lagoons are among the most productive wetlands in the Mediterranean region and play an important ecological role for many fish species. The Nador lagoon, located in the northeastern part of the Moroccan Mediterranean coast, was sampled with a beach seine at six stations during different seasons, from 2012 to 2014. Among those fish species collected, the African halfbeak, Hyporhamphus picarti, was one collected for the first time in this lagoon. This species was found only in late summer and autumn, and all the individuals captured were juveniles, indicating that the lagoon serves as an important nursery for this species. Otoliths (lapilli) microstructures of juvenile H. picarti were analyzed to estimate and compare growth rates and hatch dates of individuals caught in 2012 and 2013. The total lengths of juvenile H. picarti were (68.10 +15.19 mm) and (101.03 +28.77 mm) in 2012 and 2013, respectively, and their estimated age varied from 39 to 58 days in 2012, and from 42 to 76 days in 2013. For both years, the relationship between fish size (TL) and age (days) was described by the following linear equations: TL = 1.88×age – 19.29 (n = 52; r2 = 0.63; p< 0.05) in 2012, and TL = 2.35×age – 35.57 (n = 29; r2 = 0.71; p< 0.05) in 2013. Juveniles collected in 2013 had significantly higher growth rates (somatic and otolith growth); 1.88 mm d−1 and 2.35 mm d−1 in 2012 and 2013, respectively. For both years, the average otolith increments width increased until about the 25th day (corresponding to a size of about 28 mm TL), and then decreased. Back-calculated hatch dates of juveniles collected in the lagoon indicated that they hatched in summer from June to September. These results indicate that H. picarti has a short spawning period during the warm period, and use the lagoon as a nursery ground in late summer and autumn.
 University Mohammed V - Agdal, Faculty of Science, Laboratory of Zoology and General Biology, Rabat, Morocco

 University Mohammed V - Agdal, Faculty of Science, Laboratory of Zoology and General Biology, Ibn Battouta Av, BP 1014, Rabat, Morocco

​rabat, morocc​o, 

10000Morocco+212 6 77 59 60 91sakinajaafour@yahoo.frPresentationColonization, hatch-dates, and growth rates of juvenile Hyporhamphus picarti (Actinopterygii, Hemiramphidae), in the Nador lagoon (NE Morocco)

Hyporhamphus picarti, juvenile, otolith, growth, hatch dates, Nador lagoon, Morocco, Mediterranean Sea

  
 Ibrahim, Mohd and ShamaAl-Anbouri, Ambak, Abdul Haleem
The age and growth of Indian oil sardine Sardinella longiceps in Muscat area was determined by examining the sagittal otolith. The sessonal and sub-seasonal increments were observed and interpreted as daily and sub-daily increments respectively. The Von Bertalanffy growth model was well fitted to the length at age for both sexes polled data while sub-daily rings excluded from analysis when reading the otolith increments. The growth parameters were estimated as K= 5.0 yr-1 and Linf = 250 mm (TL). Similarly, the sub-daily rings were considered as daily rings in the analysis, representing a better fit to length age data and growth parameters which were obtained as K= 2.4 yr-1 and Linf = 235 mm (TL). The study exaimend the two given analyses when counting without and with sub-daily increments. It showed some significant differences in age and growth rate of the given analyses between 7 and 16 months of life span of the species. The latter age was more appropriate and reasonable when counting total rings as this species seemed to live for more than a year as these species attained maturity at the end of one year.
 
 
 
 
 
 
Marine Science and Fisheries Center

​Sultanate of Oman, Muscat

​Muscat

112, Ruwi, MuscatSultanate of Oman, Muscat+968-95200528camry2005@yahoo.comWorkshop on age validationPosterOtolith Based Age and Growth Studies On The Indian Oil Sardine, Sardinella longiceps Valenciennes, 1847 From Muscat, Sultanate Of Oman.

Seasonal and sub-seasonal increments, sagittal otolith, oil sardine, Muscat.

  
JamesonGregg
Accuracy in ageing is imperative for understanding population dynamics and for assessing the status of a stock. Uncertainties associated with recent assessments for the Northern stock of black sea bass, Centropristis striata, a commercially and recreationally valued species, warrant a reexamination of current ageing methods. For this study, scales and sagittal otoliths were collected from sites sampled in Southern New England and the Mid-Atlantic Bight by the Northeast Area Monitoring and Assessment Program (NEAMAP). Calcified structures, which typically display seasonal growth patterns interpreted as annuli, were analyzed without information regarding capture location, time, and fish size to minimize bias in age assignments. These preliminary studies compared various preparation methods and orientations of both otoliths and scales under a standard set of criteria. Structures were evaluated on mark clarity, reader agreement, structure growth, and processing efficiency. Future work will include year-round sampling for validation of the preferred structure. These studies will yield samples with enhanced clarity, resulting in more accurate age data for black sea bass and improved estimates of age-specific parameters considered for inclusion in the stock assessments of this species.
Virginia Institute of Marine Science

​PO Box 1346 

​Gloucester Point, VA 

23062United States8046847321jgregg@vims.eduWorkshop on age validationPosterClarity and accuracy of ageing transverse sectioned otoliths from black sea bass, Centropristis striata, from the Northwest Atlantic Ocean
  
TanjaSchulz-Mirbach
Authors: TANJA SCHULZ-MIRBACH1, Friedrich Ladich2, Martin Plath3, Brian Metscher4, Martin Heß1 1Department Biology II, Zoology, Ludwig-Maximilians-University, Germany; schulz-mirbach@biologie.uni-muenchen.de; hess@bio.lmu.de 2Department of Behavioural Biology, University of Vienna, Austria; friedrich.ladich@univie.ac.at 3Evolutionary Ecology Group, J.W. Goethe-University Frankfurt/Main, Germany; plath.ecology.evolution.behavior@gmail.com 4Department of Theoretical Biology, University of Vienna, Austria; brian.metscher@univie.ac.at Otolithic endorgans in fish function as accelerometers and serve for detecting both the position and motion of the body and sound. Important factors that influence otolith motion are otolith mass and shape. While it is still widely unknown how different shapes affect otolith movement relative to the sensory epithelium, greater otolith mass was predicted to result in enhanced stimulation of sensory hair cells and improved hearing. Sparse studies on this topic yielded different results in that they did or did not find a tight correlation between heavier otoliths and enhanced hearing. We therefore investigated the relationship between otolith morphology including (3D) models of otoliths using high-resolution microCT imaging and otolith weight as well as hearing abilities in two model systems of freshwater fishes. We compared i) surface and cave forms of the Atlantic molly (Poecilia mexicana) and ii) three cichlid species (Etroplus maculatus, Hemichromis guttatus, Steatocranus tinanti) varying in their swim bladder morphology and connection to the inner ears. Ecotypes of P. mexicana had similar hearing abilities and saccular otoliths did not differ significantly in weight. Conversely, the cichlid species showed pronounced differences in hearing abilities with the heaviest saccular otoliths found in the species displaying the best hearing sensitivities. These outcomes seem to support the predicted relationship between otolith weight and hearing abilities. But our findings also highlight the importance of 3D models which are ideally suited for future studies modeling complex otolith motion and thus may provide a better understanding of how otolith morphology contributes to inner ear functions.
LMU Munich Department Biology II

​Grosshaderner Strasse 2, Planegg-Martinsried

​Munich, Bavaria

82152Germanyschulz-mirbach@biologie.uni-muenchen.deTheme II: Community indicatorsPresentationWhat do we know about otolith function in hearing? – Insights from cichlids and livebearing fish

​hearing; inner ear function; ototlith morphology

  
Lisa AnneLibungan
Otolith shape analysis is a powerful tool to detect differences among fish populations sampled at small and large geographic scales. Information on fish population structure is important for the understanding of population dynamics, evolutionary processes and conservation of species. Here, we present shapeR, an open source software package written in the programming language R, specifically designed to collect and analyze otolith shape data. shapeR allows comparison among populations of fish within the same species sampled at small and large geographic scales. shapeR reads images into R, collects the outlines of the otoliths and performs either a Fourier or Wavelet reconstruction on the otolith outlines. Finally, shapeR provides multiple independent Fourier/Wavelet coefficients as well as other basic shape descriptors such as length, height, perimeter and area of the otolith. Using the shape descriptors it is possible to compare otolith shape variation among populations of fish with both uni- and multivariate statistical analysis. Examples will be shown how to use the package from start to end which includes reading images into R, performing quality checks when collecting otolith outlines, visualizing the mean shape of each population and finally how to compare otolith shape variation among fish populations using Canonical Analysis of Principal Coordinates, Linear Discriminant Analysis and Cluster Analysis.
University of Iceland

​Sturlugata 7

​Reykjavik

101Iceland+354 694 3835lal@hi.isTheme III: Population indicatorsPresentationshapeR: an R package to study otolith shape variation

otolith shape, population structure, R-package

  
JohannesOehm

Determining the foraging grounds of the Great Cormorant by otolith shape and chemistry

Johannes Oehm1, Andreas Zitek2, Johanna Irrgeher2, Anastassiya Tchaikovsky2, Bettina Thalinger1, Thomas Prohaska2, Michael Traugott1

1 University of Innsbruck, Institute of Ecology, Technikerstraße 25, 6020 Innsbruck, Austria


2 University of Natural Resources and Life Sciences, Division of Analytical Chemistry, VIRIS Laboratory for Analytical Ecogeochemistry, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria

 

Great Cormorants (Phalacrocorax carbo sinensis) are one of the main fish-eating birds hunting in lakes and streams of the Alpine foreland. Initially, they were only overwintering in this region, nowadays they have also established breeding colonies. As a result, freshwater fish must have faced increased perennial predation by cormorants. However, it is poorly known if the birds switch between different feeding grounds and how cormorant prey choice changes throughout the year.
This study is the first one investigating this question by characterising and provenancing otoliths of prey fish from cormorant pellets in freshwaters by (1) establishing a reference database for morphological hard part characterisation and (2) strontium isotopic analysis. During breeding season and winter roost regurgitated pellets of the birds were collected fortnightly for two years at lake Chiemsee (Bavaria, Germany). Prey remains were identified using morphological hard part analysis. Differences in water chemistry between different potential feeding grounds and resulting reflection of this information in otoliths (elemental pattern and 87Sr/86Sr isotope ratio) were evaluated by analysing water samples and otoliths from reference fish collected from lake Chiemsee and its surrounding water bodies using inductively coupled plasma-mass spectrometry (ICP-MS). Additionally, species-specific differences in otolith chemistry of fish from the same site were investigated. Furthermore, otolith shape analysis was performed to examine differences in shape between different water bodies.

The reference data can now be used to classify the otoliths from cormorant pellets according to their origin, and, consequently, for determining the foraging range of cormorants in the Alpine foreland.

University of Innsbruck, Institute of Ecology

University of Innsbruck, Institute of Ecology, Technikerstraße 25, 6020 Innsbruck, Austria

Innsbruck​

6020Austria0043 512 507 51672johannes.oehm@uibk.ac.atTheme I: Environmental indicatorsPresentationDetermining the foraging grounds of the Great Cormorant by otolith shape and chemistry

Alpine foreland, seabird, piscivorous, freshwater fish, feeding ecology, foraging range, prey provenancing, strontium isotopes

  
KarinLimburg
Eye lenses are formed of the protein crystallin, and grow throughout an organism’s life. The external cells are metabolically active whereas the interior cells are not, but remain in place and essentially isolated, i.e. not subject to metabolic re-working. We have been studying the feasibility of using eye lens chemistry as a complement to otolith chemistry. Eye lenses have very little calcium and strontium, thus easing the ability to detect other trace elements. We have produced 2-D maps of fish lens chemistry using scanning X-ray fluorescence microscopy at the Cornell synchrotron. We consistently detect bromine, copper, rubidium, selenium, and zinc across a wide range of fish taxa; and in some cases we detect mercury and other trace elements such as lead or gold. We will discuss the feasibility of using the chemical “information” archived in eye lenses as a complement to that archived in otoliths.
State University of New York College of Environmental Science and Forestry

​Illick Hall​, 1 Forestry Drive

​Syracuse, NY

13210USAklimburg@esf.eduTheme I: Environmental indicatorsPresentationShades of Sophie Dove?  The potential of eye lens chemistry as a complementary archive of environmentally relevant information

​eye lens chemistry; complementary archival structure

  
YoussefEL HABOUZ
Otolith identification system based on image contour analysis Y. EL HABOUZ1, Y. ES-SAADY1, M. EL YASSA1, D. MAMMASS1, F.NOUBOUD2, A. CHALIFOUR2 1 IRF-SIC Laboratory, University Ibn Zohr, Agadir, Morocco, elhouzyoussef@gmail.com, y.essaady@uiz.ac.ma, melyass@gmail.com, mammass@uiz.ac.ma 2LIRICS, University Trois-Rivières, Québec, Canada. fathallah_nouboud@uqtr.ca, alain_chalifour@uqtr.ca Abstract. In this paper we present an automatic classification system of fish species based on otolith contour analysis. Otolith has a distinctive external form which is usually a characteristic of the species. The external shape of the Otolith varies according to species, but it’s substantially constant in the same species. This can be used as a characteristic of fish species recognition. Identification of fish species using Otoliths is a major issue in many marine ecological studies. For example, the Otoliths recovered from the stomach or feces could be used to determine the food spectrum. The proposed system consists of three main phases: pre-processing, feature extraction and classification. The first phase is the image denoising and enhancing grayscale contour to facilitate the detection and contour extraction. In the second phase, we extract the median distance vector of the contour. This vector is used in Otolith recognition phase, which is based on the Support Vector Machine (SVM) classification method. The system was tested on a set of 60 fish Otolith images from AFORO database, 10 images per species for six species (Scomber colias, Coris julis, Umbrina canariensis, Diplodus annularis, Trachurus mediterraneus and Trisopterus minutus). The experimental results show the robustness of the approach (98.33%). Keywords: Otoliths, Fish, Species, AFORO, Image, Contour, Median distance, Recognition, Classification, SVM.
IRF-SIC Laboratory, University Ibn Zohr

IRF-SIC Laboratory, University Ibn Zohr​,BP 8106, Cité DAKHLA, AGADIR

​AGADIR

80000Morocco+212676114145elhabouzyoussef@gmail.comWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPresentationOtolith Identification System Based On Image Contour Analysis

​Otoliths, Fish, Species, AFORO, Image, Contour, Median distance, Recognition, Classification, SVM.

  
IgaratzaFraile
I. Fraile1, H. Arrizabalaga1, J. Santiago1, I. Arregi1, J. Rooker2 and D. Wells2
 
1 AZTI Tecnalia, Marine Research Division, Herrera Kaia, Portualdea z/g E-20110 Pasaia, Gipuzkoa, Spain (Tel.:+34946574000; Fax: +34946572555)
 
2 Department of Marine Biology, Texas A&M University, 1001 Texas Clipper Road, Galveston, Texas 77553 USA
 
Trace elements  and stable isotopes in otoliths of North Atlantic albacore tuna (Thunnus alalunga), collected from the different feeding grounds in the eastern North Atlantic were measured and compared among sampling locations and life history stages. Elemental and isotopic fingerprints measured in core and edge zones were used to determine if albacore tuna captured at different locations (inshore waters of the Bay of Biscay vs. Atlantic offshore waters including southern Celtic Sea) have the same nursery origin and migratory patterns. Otolith edge geochemical signatures proved to be a valuable tool for classifying individuals to their capture locations. Multivariate analysis of the trace element and stable isotope values of the otolith edge reflected a clear differentiation between sampled locations. Among the element analysed, Sr concentration appeared to accurately reflect ambient physicochemical conditions, and served as a good proxy to differentiate capture locations. δ18O, δ13C, Sr:Ca, Mg:Ca and Ba:Ca during the early life history stages (0 to 6 month of life) were relatively invariant across the two capture locations, but Mn concentrations differed significantly among albacore tuna captured in coastal waters of the Bay of Biscay and in Atlantic offshore waters. Mn concentrations were higher in fishes captured in the Bay of Biscay, suggesting a higher growth rate during the early stages compared to fishes captured in offshore waters. Annual cycles of Sr:Ca ratios were visible along the otolith ablation transects reflecting an annual migratory pattern between water masses of differing salinities. Sr:Ca cycles were visible during the early life history stages for most of the juvenile albacore captured in the Bay of Biscay, coinciding with a high accumulation of Sr during the winter, whereas this periodicity was visible only in later stages in fish from offshore waters.
AZTI Tecnalia, Marine Research Division

Herrera Kaia, Portualdea z/g ,

Pasaia, Gipuzkoa

E-20110 Spain (Tel.:+34946574000; Fax: +34946572555)ifraile@azti.es Theme III: Population indicatorsPresentationMovements of the North Atlantic albacore (Thunnus alalunga) revealed by otolith δ18O, δ13C, Sr:Ca, Mg:Ca, Mn:Ca and Ba:Ca chronologies

​albacore tuna, edge, core, stable isotope, trace element, migration routes

  
IgaratzaFraile
I. Fraile1, H. Arrizabalaga1, J. Santiago1, N. Goñi1, and J. Rooker2
1 AZTI Tecnalia, Marine Research Division, Herrera Kaia, Portualdea z/g E-20110 Pasaia, Gipuzkoa, Spain (Tel.:+34946574000; Fax: +34946572555)
2 Department of Marine Biology, Texas A&M University, 1001 Texas Clipper Road, Galveston, Texas 77553 USA
Atlantic bluefin tuna, Thunnus thynnus, is a large migratory fish with a extremely wide distribution over the North Atlantic Ocean and adjacent seas. A better understanding of its temporal and spatial movements may provide data for improving stock assessment and developing management strategies. We tested the utility of trace element signature in otoliths as a natural tag to study the movements of Atlantic bluefin tuna, Thunnus thynnus, “into” and “out” of the Mediterranean Sea. The elements Mg, Sr, Ba and Zn in the otoliths of Atlantic bluefin tuna, collected in the Mediterranean Sea and Atlantic were measured by laser-ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Trace elements concentration at the outer edge of the otolith (which reflects fish’s recent environmental history) of the two regions was compared by statistical techniques. Mean Ba:Ca and Sr:Ca ratios were significantly higher in the Mediterranean Sea compared to the open Atlantic Ocean, whereas Mg:Ca ratio was higher in the open ocean. Classification accuracy of four different multielement classification methods was compared: Linear Discriminant Analysis (LDA), Quadratic Discriminant Analysis (QDA), Random Forest (RF) and Artificial Neural Network (ANN). Given the difficulties to fulfil the underlying assumptions of LDA and QDA methods, RF was selected as the optimal model for our data, with a classification accuracy of 89.17%. Barium (Ba) was the only element selected by all discrimination methods, thus it has been identified as particularly useful for Mediterranean-Atlantic discrimination. Variation of Ba/Ca ratio along the otolith growth axis could be used to investigate bluefin tuna movements between the Mediterranean Sea and Atlantic Ocean.
 
AZTI Tecnalia, Marine Research Division

​Herrera Kaia,Portualdea z/g

​Pasaia, Gipuzkoa

E-20110Spain +34946574000ifraile@azti.es Theme III: Population indicatorsPresentationOtolith elemental composition as a proxy for Atlantic bluefin tuna (Thunnus thynnus) migratory movements between the Atlantic Ocean and Mediterranean Sea

bluefin tuna, otolith edge, trace element, movements, Atlantic Ocean, Mediterranean Sea

  
JianYang
Estuarine tapertail anchovy (Coilia nasus) is an anadromous species, and adult C. nasus migrates to the Yangtze River for spawning from sea areas in early February to the end of April. C. nasus is a highly commercial and valuable species in China due to its delicacy and traditional consumption culture. The anchovy from the Yangtze River is probably the most expensive fish in the world. The maximum price even reached as high as about $1000/kg, and $9600 for a single fish with 45.3 cm TL and 0.325 kg BW in Jiangsu Province in 2012. Because of empirical limitations with the current methods of catch-survey analysis, it remains difficult to effectively understand the exact location of spawning sites, the diadromous migration features of this species, and the relationship between the anchovy stocks among the Yangtze River, and its connected lakes and adjacent seas. In the present study, we collected C. nasus anchovies from mainstream and estuary of the Yangtze River, river-connected lakes (the Taihu Lake and Poyang Lake), and estuary adjacent seas (the Yellow Sea and East China Sea). Their otolith Sr and Ca was analyzed by EPMA to estimate the habitat history. At the same time, body morphology and otolith microstructure were investigated for the purpose of mutual corroboration. Our results suggest, for the first time, that C. nasus migrates anadromously for spawning into the Poyang Lake, which locates more than 800 km upstream of the Yangtze River mouth. Furthermore, a relatively close connectivity may exist between the C. nasus anchovies of the Yangtze River and the adjacent Yellow Sea. C. nasus grows in the Yangtze River nearly for one year, and then enters the brackish and sea water habitats which can be a nearly straight line for even as far as 300 km off the coastline.
Key Laboratory of Ecological Environment and Resources of Inland Fisheries, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences

Shanshui East Road No. 9

​Wuxi City, Jiangsu Province

214081China0510-85557823jiany@ffrc.cn, fporpoise@hotmail.comTheme I: Environmental indicatorsPresentationAn investigation of connectivity among estuarine tapertail anchovies Coilia nasus from the Yangtze River, Yellow Sea and Poyang Lake

​Estuarine tapertail anchovy Coilia nasus, otolith, microchemistry, microstrusture, connectivity, the Yangtze River

  
BenjaminWalther
Artificial chemical marking of calcified structures, such as otoliths, has emerged as a powerful method to assess stocking success and determine connectivity patterns in fresh and marine systems. Although transgenerational and larval immersion methods have been validated, dietary transmission of enriched stable isotopes to calcified structures would allow minimal handling of animals and reduced expense for flow-through systems. A series of experiments were conducted to validate the feasibility of this method. First, we experimentally manipulated 137Ba in diets and successfully marked otoliths in red drum Sciaenops ocellatus larvae, fingerlings and sub-adults as well as fin rays and scales of sub-adults. After two weeks, marking success of otoliths was 100% for larvae and fingerlings reared at higher temperatures, indicating the need for sufficient growth to occur for consistently detectable marks. Spiked Ba successfully marked fin rays (86% marked) and scales (100% marked) of sub-adults, providing a cost-effective method for marking structures that can be sampled non-lethally. Second, we manipulated both 138Ba and 86Sr in diets over four weeks and evaluated uptake of each isotope spike into otoliths. Otoliths were successfully marked with Ba isotopes and stabilized after two weeks of exposure, whereas dietary transmission of the Sr isotope spike was not successful. We used a concentration-dependent mixing model to explore the potential influence of relative differences in water and dietary elemental concentration to explain differential marking success of Ba and Sr in marine systems. This mixing model will be useful for future workers to estimate the feasibility of dietary spiking in various systems with divergent water chemistry. Where feasible, dietary marking of calcified structures may be the method of choice where handling must be minimized or water chemistry cannot be manipulated.
University of Texas

​750 Channel View Drive

Port Aransas​, Texas

78373USA361-749-6810bwalther@utexas.eduTheme III: Population indicatorsPresentationDietary transmission of isotope spikes to otoliths, fin rays and scales: experimental validation and concentration-dependent mixing models

​Isotope marking, diet, barium, strontium, isotopes, fin rays, scales, otoliths

  
Jian Yang
Estuarine tapertail anchovy (Coilia nasus) is an anadromous species, and adult C. nasus migrates to the Yangtze River for spawning from sea areas in early February to the end of April. C. nasus is a highly commercial and valuable species in China due to its delicacy and traditional consumption culture. The anchovy from the Yangtze River is probably the most expensive fish in the world. The maximum price even reached as high as about $1000/kg, and $9600 for a single fish with 45.3 cm TL and 0.325 kg BW in Jiangsu Province in 2012. Because of empirical limitations with the current methods of catch-survey analysis, it remains difficult to effectively understand the exact location of spawning sites, the diadromous migration features of this species, and the relationship between the anchovy stocks among the Yangtze River, and its connected lakes and adjacent seas. In the present study, we collected C. nasus anchovies from mainstream and estuary of the Yangtze River, river-connected lakes (the Taihu Lake and Poyang Lake), and estuary adjacent seas (the Yellow Sea and East China Sea). Their otolith Sr and Ca was analyzed by EPMA to estimate the habitat history. At the same time, body morphology and otolith microstructure were investigated for the purpose of mutual corroboration. Our results suggest, for the first time, that C. nasus migrates anadromously for spawning into the Poyang Lake, which locates more than 800 km upstream of the Yangtze River mouth. Furthermore, a relatively close connectivity may exist between the C. nasus anchovies of the Yangtze River and the adjacent Yellow Sea. C. nasus grows in the Yangtze River nearly for one year, and then enters the brackish and sea water habitats which can be a nearly straight line for even as far as 300 km off the coastline.
Key Laboratory of Ecological Environment and Resources of Inland Fisheries, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences

Shanshui East Road No. 9

Wuxi City, Jiangsu Province

214081China+86-510-85557823jiany@ffrc.cnTheme I: Environmental indicatorsPresentationAn investigation of connectivity among estuarine tapertail anchovies Coilia nasus from the Yangtze River, Yellow Sea and Poyang Lake

Estuarine tapertail anchovy Coilia nasus; otolith; microchemistry; microstrusture; habitat; connectivity; the Yangtze River

  
PABLOARECHAVALA-LOPEZ
Farming sea bream (Sparus aurata L.) and sea bass (Dicentrarchus labrax L.) in open-sea cages has risen during the last decades, and consequently, problems also began to arise concerning escape events. Escapees might lead to economic losses and environmental problems in coastal ecosystems, which might be monitored and evaluated to further management strategies. Thus, it is necessary to develop indicators to distinguish between the wild and farm origin of such escapees within native populations. Based on the fact that cultured fish grow in a different environment from in the wild, feeding on different trophic resources and resulting in faster growth and frequently different growth patterns, it might be expected that they also show morphological and chemical differences according to fish origin in sagittal otoliths. To test this, sea bream and sea bass individuals from farm facilities and wild assemblages were sampled in Spain and Greece. Variation in otolith morphology was examined through conventional shape descriptors (i.e. area, perimeter, circularity, roundness, mass, and height-length relationship) and elliptic Fourier descriptors (EFDs). Discriminant analysis with either all shape descriptors together or EFDs was able to classify with high accuracy both sea bream (89.5-95.7%) and sea bass (93.2-95.2%) according to their origin. Variations in trace element compositions (i.e. Mg, Al, K, Mn, Fe, Co, Ni, Cu, Zn, Sr, Ag, Ba, Pb) between fish origin for both species were also analysed. Classification through discriminant analysis with 13 trace elements showed high percentages regarding the wild and farm origin, for both sea bream (83.3-89.8%) and sea bass (87-100%). Hence, this study recommends the use of morphological characteristics and trace elements compositions of otoliths as useful indicators of sea bream and sea bass origin, and therefore, as fisheries management tools.
University of Alicante

Dept. of Marine Science and Applied Biology. 

Edificio Ciencias V.

​Campus de San Vicente s/n.

​Alicante

03690Spain+34 965903473pablo.arechavala@ua.esTheme I: Environmental indicatorsPosterOTOLITHS AS INDICATORS OF WILD OR FARM ORIGIN OF SEA BREAM AND SEA BASS

​morphology, shape, trace elements, escapees, fish farms, marine environment, management tools

Pablo Sanchez-Jerez, Dept. Marine Science and Applied Biology, University of Alicante, Alicante, Spain

  
ThomasHelser
The bomb-produced radiocarbon (14C) chronometer has become the gold standard for assessing the accuracy of otolith growth ring based fish age estimates. In the northeast Pacific Ocean, nearly a dozen age validation studies have been conducted, ranging from California to Alaska, most of which have relied on a single reference chronology from the Gulf of Alaska. We developed a Bayesian hierarchical model using data sets of bomb-produced radiocarbon in the northeast Pacific Ocean and investigated whether latitude and upwelling exerts an influence on the parameters that describe the rapid Δ 14C increase in marine calcium carbonates. Models incorporating both latitude and upwelling as linear covariates of a 4-parameter logistic model were favored based on ∆DIC statistics. There was substantial evidence to support that the timing of the Δ14C pulse was advanced and that total Δ14C uptake increased with increasing latitude. In contrast, increased oceanographic upwelling resulted in lower total radiocarbon input as well as a delay in the timing of the pulse curve, as was demonstrated in the upwelling dominated California Current System. Within the observed latitudinal and upwelling range of the data sets examined in this study the predicted timing of the bomb pulse curve varied by as much as 3 years, which could be misinterpreted as ageing error. Our results suggest that new reference chronologies may be needed for regions of the North Pacific Ocean differing in latitude, seasonal upwelling strength and other mixing factors that can potentially change the functional form of the Δ14C curve.
NOAA Fisheries, National Oceanic and Atmospheric Administration

Alaska Fisheries Science Center, 7600 Sand Point Way

​Seattle, Washington

98115USA12065264200thomas.helser@noaa.govTheme I: Environmental indicatorsPresentationModelling Environmental Factors Affecting Assimilation of Bomb-produced Δ14C in the North Pacific Ocean: Implications for age validation studies

​Age validation, Bayesian models, hierarchical models, North Pacific Ocean, bomb-produced radiocarbon, carbon isotope,

  
ThomasHelser
Fish otolith oxygen isotope ratios (18O) are considered “flight recorders,” providing records of sea water temperature and habitat use over the animal’s life span. We measured 18O values in modern and archeological Pacific cod otoliths using a high precision ion microprobe. Values of δ18O were measured in as many as eighty 10-micron spots along transects from the otolith core to its margin with high spot-to-spot analytical precision (δ18O ±0.3‰). We obtained sample densities along a linear transect that were at least 2 to 3 times greater than micromilling/conventional mass spectrometry techniques. From modern Pacific cod otoliths (using in situ temperatures from electronic archive tags) we calibrated the fractionation equation of aragonite (r2 = 0.75, p
NOAA Fisheries, National Oceanic and Atmospheric Administration

​Alaska Fisheries Science Center, 7600 Sand Point Way, N.E.

​Seattle

98115USA12065264200thomas.helser@noaa.govTheme I: Environmental indicatorsPresentationA 200 year archeozoological analysis of Pacific cod life history as revealed through Ion Microprobe oxygen isotope ratios in otoliths

Oxygen isotope, Ion microprobe, Archeological Pacific cod otolith, fractionation equilibrium, Gulf of Alaska, Climate change

  
AllenAndrews
Refinements to the methodology of bomb radiocarbon dating made it possible to validate age estimates of the humphead wrasse (Cheilinus undulatus) and bumphead parrotfish (Bolbometopon muricatum). Age for these species have been estimated from presumed annual growth zones in otoliths to near 30 to 40 years, respectively. The validity of these estimates was tested using bomb radiocarbon dating on the small and fragile otoliths of these species, and provided an opportunity to refine the method using advanced technologies. A regional ∆14C reference record from hermatypic coral cores from the Great Barrier Reef was assembled and ∆14C measurements from extracted otolith cores of adult otoliths was successful. Validated ages supported the accuracy of growth-zone derived ages using sectioned sagittal otoliths and refinements made in this study indicate bomb radiocarbon dating can be used on other species with small otoliths.
NOAA Fisheries - Pacific Islands Fisheries Science Center

1845 Wasp Boulevard - Building 176

​​Honolulu, Hawaii

 96818USA(808)388-2776allen.andrews@noaa.govWorkshop on age validationPresentationRefined bomb radiocarbon dating of two iconic fishes of the Great Barrier Reef

Carbon-14, bumphead parrotfish, Bolbometopon muricatum, humphead wrasse, Cheilinus undulatus, Labridae, micromilling, otolith, Australia

  
Diana, CliveShores, Trueman
Metabolism is a fundamental biological process that controls or explains a wide variety of biological traits and ecological patterns.  Metabolic rate (MR) is directly linked to temperature, thus climate change is predicted to impact MR.  Due to the inaccessible nature of marine species there are few measurements of field MR available for marine teleost fishes, especially deep-sea species which cannot be maintained in laboratory conditions. The isotopic composition of carbon in otoliths has been linked to MR in several previous studies but to date this link has not been exploited to infer MR in wild fishes.  The growth properties of otoliths mean that changes in individual MR through ontogeny could also be determined. Otoliths are widely accessible, and large historic archives exist across global fisheries, potentially allowing tests of changes in field MR in response to temperature or other ecological variables. There is, therefore, a strong incentive to validate otolith carbon isotopes as a proxy for field metabolic rate.
In this study otolith samples from c.150 individuals of fishes inhabiting the UK continental slope between 500 and 2000m were analysed using stable isotope analysis.  The relationship between otolith carbon isotope ratios and factors known to influence MR such as body size and temperature was assessed within and between species. Results are promising, suggesting that otolith carbon isotope analysis can be used as a new method of measuring field MR that could be applied retrospectively to teleost fishes. 
University of Southampton

​National Oceanography Centre, Southampton, University of Southampton Waterfront Campus, European Way

​Southampton

SO14 3ZHEngland01264 710474ds3g08@soton.ac.ukTheme II: Community indicatorsPresentationStable carbon isotopes in marine fishes otoliths

​otolith, metabolism, isotopes

  
StephenWischniowski
Sagittal otoliths from juvenile Pacific halibut (Hippoglossus stenolepis) of known age were used to create a bomb-produced radiocarbon reference chronology for the eastern Bering Sea (EBS) by fitting a coupled-function model to Δ14C values from each specimen’s birth year. The newly-created EBS reference chronology was then compared to a reference chronology previously created for Pacific halibut from the Gulf of Alaska (GOA). A Bayesian model was developed and Markov Chain Monte Carlo simulation was used to estimate model parameters and ageing bias between reference chronologies and validations samples. Differences in reference chronologies between ocean basins were reflected in large ΔDIC (deviance information criterion) between models, supporting the hypothesis that two separate coupled-function models were required to adequately describe the data, one each for the EBS and GOA. We determined that regional oceanography plays a considerable role in the Δ14C values, and must be taken into consideration when selecting a reference chronology for bomb-produced 14C age validation studies. We also analyzed adult EBS Pacific halibut otoliths to validate age determination accuracy. Although the EBS and the GOA ocean basins did exhibit differences in the nature of 14C acquisition within the reference chronology’s, the results from validation samples, however, indicate that the current ageing methodology used in Pacific halibut assessments is accurate and has provided accurate age assignments for both ocean basins.
Sclerochronology Laboratory Pacific Biological Station Fisheries & Oceans Canada

3190 Hammond Bay Road

Nanaimo, British Columbia 

V9T 6N7Canada(250) 756-7125stephen.wischniowski@dfo-mpo.gc.caWorkshop on age validationPosterIncorporation of bomb-produced 14C into fish otoliths.  An example of basin-specific rates from the North Pacific Ocean

​Pacific halibut

age validation

bomb carbon


Craig R. Kastelle

Timothy Loher

Thomas E. Helser

  
Bochra MARSAOUI
OTOLITHOMETRIC COMPARATIVE STUDY OF TWO LAGOON’S POPULATIONS OF NORTHERN LAKE AND SOUTHERN LAKE OF GILTHEAD SEABREAM SPARUS AURATA OF TUNISIA

Bochra MARSAOUI 1, R. MESSAOUD 1, M. KHEDER 1, M. FATNASSI 1, M. TROJETTE 1, M. REBAYA 1, A. CHALAH 2, J-P. QUIGNARD 3 & M.TRABELSI 1
 
(1) Unité des Biologie marine, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie
(2) Unité de génétique des populations et ressources biologiques, Université Tunis El Manar, Tunis, Tunisie
(3) Laboratoire d’Ichtyologie, Université Montpellier II, Montpellier, France
 

In bony fish, the inner ear contains three pairs of Otoliths in the skull of the fish, just under the back of the brain. It typically preserves the sagittal Otoliths, because they are larger and easier to find.
The present study was based on the morphological analysis of the Sagitta of Sparus aurata from two lagoons environment, the North Lake and South Lake of Tunis.
The Sagitta are extracted by dissection, washed, wiped and then photographed.
A discriminant analysis is applied to all Otoliths of both populations to illustrate the differences and/or the similarities between the two populations, and this after having treated otolith’s photos by software « Photoshop » et « Shape ».
The results obtained show highly significant differences, on one hand , between otoliths of the same population, and on another hand, between right and left Otoliths of the two populations.
These populations inter asymmetries can be explained by the fact that the two batches of fish are different and that each population is faithful to its lagoon.
While that intra-populational differences could be the result of a hydrodynamic stress.

 Keywords: Sparus aurata, Otoliths, North lake, South lake, Tunisia.

marsaouibochra@gmail.comWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPosterOTOLITHOMETRIC COMPARATIVE STUDY OF TWO LAGOON’S POPULATIONS OF NORTHERN LAKE AND SOUTHERN LAKE OF GILTHEAD SEABREAM SPARUS AURATA OF TUNISIA

  
Manel FATNASSI
COMPARING OTOLITH SHAPE FOR STOCK DISCRIMINATION OF TRACHINUS DRACO (TRACHINIDAE) IN TUNISIAN WATERS:
RAF-RAF (OCCIDENTAL COAST) & MONASTIR (ORIENTAL COST)
 
Manel FATNASSI 1*, Nour El Houda MAHOUACHI 1, Mouna TROJETTE 1, Abdellah CHALAH 2, Jean-Pierre QUIGNARD 3 & Monia TRABELSI 1
 
1 Unité de Biologie Marine, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie.
2 Unité de Génétique des Populations et Ressources Biologiques, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie.
3 Laboratoire d'Ichtyologie, Université Montpellier II, Montpellier, France.

Otoliths are dense limestones found in the inner ear of bony fish, including: the Sagitta, the lapilli and the asteriscus. Otolith shape has been proven to be specific for the species and, also, for populations.
The variation in the shape morphology of the otoliths, are reported to be due to environmental characteristics or genetically induced.
In this study, first in Tunisia, the analysis of otolith shape is studied to separate the analyzed stocks and identify morphological differences of the contour’s otoliths, using statistical software. These analyzes are applied on the Sagitta, because it is the biggest.
The variability of the otolith shape contour of Trachinus draco (Trachnidae), in Tunisian waters, are analyzed to discriminate two lots sampled from two different sites: Raf-Raf (west coast) and Monastir (eastern coast). The both sites are compared by their peers and sex of the fish.
The contour of the otolith has been shown to be a good tool to differentiate stocks of Trachinus draco in Tunisian waters. In this part of the stock discrimination, we can confirm that the otolith is a very simple technique, leading to reliable results similar to those that can be found by genetics.

 Keywords: Trachinus draco, sagittal otolith, shape variability, male, female, RafRaf, Monastir, Tunisia.
marsaouibochra@gmail.comWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPosterCOMPARING OTOLITH SHAPE FOR STOCK DISCRIMINATION OF TRACHINUS DRACO (TRACHINIDAE) IN TUNISIAN WATERS:
  
Maissa KHEDHER
IMPORTANCE OF OTOLITH MORPHOLOGY IN THE DISCRIMINATION OF TWO TUNISIAN POPULATIONS OF MUGIL CEPHALUS (SEA OF TABARKA AND GHAR EL MELH LAGOON)

Maissa KHEDHER 1,
M. FATNASSI 1, M. TROJETTE 1, B. MARSAOUI 1, M. REBAYA 1, R. MESSAOUD 1,  N-H. MAHOUACHI 1, A. CHALAH 2, J-P. QUIGNARD 3 & Monia TRABELSI 1

(1)Unité de Biologie Marine, Faculté des Sciences, Université  Tunis El Manar, Tunis, Tunisie
E-mail: khedher.maissa@gmail.com
(2) Unité de Génétique des Populations et Ressources Biologiques, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie
(3) Laboratoire d’Ichtyologie, Université Montpellier II, Montpellier, France

During this decade, there was an important development in the domain of halieutic sciences, established on a major party on technological advances in extracting information from fish’s Otoliths. That’s why; otolithometry is actually used in the most research. This work is based on the morphological study of otolith of Mugil cephalus; fish’s which were taken from Ghar El Melh Lagoon and Tabarka Sea.
These Otoliths were studied in the order to illustrate the differences and similarities between two populations by multidimensional analysis and discrimination factorial analysis (D. F. A.) after otolith’s photo processing by using Photoshop and Shape Software.
The results show that the two populations are separated by axis F1 (absorption= 47, 66).
For both populations, the right and left otoliths of the two sexes (male and female) are separated by the axis F2 (absorption = 10, 64).
Statistical analyzes showed, also, a significant differences between the two groups of fish (p-value <0.05) differences. This shows the uniformity of sea and lagoon populations.

Keywords: Mugil cephalus, Otoliths, Sea of Tabraka, lagoon of Ghar El Melh, Tunisia.
marsaouibochra@gmail.comWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPosterIMPORTANCE OF OTOLITH MORPHOLOGY IN THE DISCRIMINATION OF TWO TUNISIAN POPULATIONS OF MUGIL CEPHALUS (SEA OF TABARKA AND GHAR EL MELH LAGOON)
  
Mouna Trojette
STUDY OF THE MORPHOLOGICAL VARIATION OF THE OTOLITH OF FISH (SCORPAENA PORCUS) BETWEEN A MARINE ENVIRONMENT (HAMMAM-LIF) AND A MIDDLE ISLAND (DJERBA) IN TUNISIA

Mouna Trojette 1,
M. FATNASSI 1, B. MARSAOUI 1, M. KHEDHER 1, M. REBAYA1, R. MESSAOUD 1,  N-H. MAHOUACHI 1, A. CHALAH 2, J-P. QUIGNARD 3 & Monia TRABELSI 1

(1)Unité de Biologie Marine, Faculté des Sciences, Université  Tunis El Manar, Tunis, Tunisie
(2) Unité de Génétique des Populations et Ressources Biologiques, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie
(3) Laboratoire d’Ichtyologie, Université Montpellier II, Montpellier, France
E-mail: Mayna_bio@hotmail.com
 
Otoliths are mineralized concretions in the inner ear of teleost fishes. Each bony fish has 3 pairs of otoliths: Saccular and lagenaires Otoliths are used for hearing and twin otolith helps the fish to maintain balance. At the population level, otolith data allow tackling the recruitment, mortality and can reveal the spatio-temporal structuring of stocks and fish populations.  The basis of this study is the detection of the polymorphism between the two populations of Scorpaena porcus, in the first hand, and between the otoliths of each population, in the other hand. The database is subject to a discriminant analysis (F.D.A.) to illustrate the differences and/or similarities between the observed groups and optimize the variability existing between them. These analyzes showed the presence of two distinct populations. Thus, Symmetries have been revealed between left and right Otoliths for the population of Hammam-Lif, unlike that of Djerba. These results are confirmed by various statistical tests: Distances Mahalanobis P-value for Fisher distances where the distances between pairs of otoliths is either significant (<0.05), case of the island's population (Djerba Island) or significant name (> 0.05) in cases of marine populations (Hammam Lif). 

Keywords: Scorpaena porcus, Otolith, Discrimination stocks, Symmetry, Asymmetry, Hammam Lif, Djerba.

marsaouibochra@gmail.comWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPosterSTUDY OF THE MORPHOLOGICAL VARIATION OF THE OTOLITH OF FISH (SCORPAENA PORCUS) BETWEEN A MARINE ENVIRONMENT (HAMMAM-LIF) AND A MIDDLE ISLAND (DJERBA) IN TUNISIA

  
Natalya V.Zuykova
The research is based on data of comparative Northeast Arctic (NEA) cod age-readings carried out in 1992-2012 by the two national institutes: Polar Research Institute of Marine Fisheries and Oceanography (PINRO), Murmansk, Russia, and the Institute of Marine Research (IMR), Bergen, Norway. There were 8,184 pairs of NEA cod otoliths read and compared to assess the difference in age determination between the two laboratories during this period. Differences in age determination were revealed between individual age readers and laboratories as well as between initial and repeated age readings of the same reader. Earlier examination of age reading results of NEA cod conducted by the two laboratories demonstrated biases in age determination of some age groups. Fish age determinations are used in most stock assessment models based on cohort analysis. Errors in age determination might affect stock estimates and subsequent management advice. As the NEA cod stock estimates are currently based on joint data from Russia and Norway, it is rather difficult to assess potential effect of systematic age reading errors in the stock estimates. Therefore, two different stock estimates based either on IMR or on PINRO age determinations were performed to find out possible range in stock size and its status.
 Polar Research Institute of Marine Fisheries and Oceanography (PINRO)

​6 Knipovich Street 

​Murmansk

183038Russia​+78152472231zunat@pinro.ruTheme III: Population indicatorsPosterImpact of bias in age reading of the Northeast Arctic cod on stock assessment

NEA cod, age-reading errors, bias, stock assessment

​Natalia A. Yaragina, Yury A. Kovalev,  Anatoli A. Chetyrkin​​

  
FabienMorat
Understanding the influence of environmental characteristics on the age and growth of young-of-the-year is a fundamental challenge in ecology. Young-of-the-year (YOY) chub (Cyprinidae, Squalius cephalus) were collected in the Lower Rhône River (South of France) along the shoreline of a 30-km hydraulic reach. The spatial distribution, age, hatching period and daily growth rate (DGR) of the YOY otolith were investigated to evaluate differences in four contrasted areas along the reach (a by-passed section, tailrace, confluence area and reservoir). The otolith shape analysis clearly distinguished the areas into three groups (the by-passed section, the tailrace and a third group formed by the reservoir and the confluence individuals). The mean age of fish from the medium-size class varied according to areas from 149 days for the tailrace to 166 days for the by-passed section. The estimated hatching period extended from mid-February to the beginning of June with a peak in April and May. The otolith DGR showed similar curve profiles for the four areas with low values during winter and spring (~1.0 µm d-1) and a large increase in summer (between 1.9 µm d-1 and 2.4 µm d-1 on average). These variations seemed in agreement with the 2013 hydro-climatic context. However, differences in the DGR curve profiles among the areas were observed from August to mid-September. The highest DGR values (~2.8 µm d-1) were estimated for YOY of the tailrace and the lowest for fish in the by-passed section (~2.1 µm d-1). These differences could reflect local variations in the habitat conditions.
IRSTEA

Centre d'Aix en Provence, 3275 Route de Cézanne, CS40061

​Aix en Provence

13182Francefabien.morat@irstea.frTheme IV: Individual indicatorsPresentationVariability of the otolith growth rate and age of young-of-the-year chub, Squalius cephalus (Linnaeus, 1758), from a hydraulic reach in the Rhône River.

Squalius cephalus, Rhône River, otoliths, age, growth rate

  
ManelFATNASSI
The utility of otolith shape analysis for stock discrimination of Trachinus draco (Trachinidae) in the Northern Tunisian waters (Raf-Raf and kelibia)
 
Manel FATNASSI 1*,
Nour El Houda MAHOUACHI 1, Mouna TROJETTE 1, Abdellah CHALAH 2
Jean-Pierre QUIGNARD 3 & Monia TRABELSI 1
 
1 Unité de Biologie Marine, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie.
2 Unité de Génétique des Populations et Ressources Biologiques, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie.
3 Laboratoire d'Ichtyologie, Université Montpellier II, Montpellier, France.

Otoliths are calcified bones localized in the left and right inner ear of the fish.
The analysis of otolith shape can be used to discriminate species and/or stocks within the same species.
The symmetry of the otolith shape is a specificity to indicate whether the morphology is similar in the right and left inner ears and discriminate also the fish stocks.
The different physico-chemical parameters (temperature, pH, oxygen, etc) and environmental conditions (pollution, stress, etc) have an important influence on the morphological variability of otoliths.
The analyses of the contour shape of the otoliths are studied on Trachinus draco, in Tunisian waters, captured from two sites: Raf -Raf and Kelibia (Northern Tunisia). The photos of left and right otoliths are scanned and treated according to the technique of Elliptical Fourier Analysis.
A comparison is made between peers of otoliths and between males and females of Trachinus draco. However, in Tunisia, no work has been done on this species.
This study confirms the importance utility of the technique of otolith shape analysis (Elliptical Fourier Analysis) to discriminate different stocks.
 
 Keywords: Trachinus draco, Elliptical Fourier analysis, otolith shape analysis, male, female, RafRaf, Kelibia, Tunisia.

marsaouibochra@gmail.comTheme II: Community indicatorsPosterThe utility of otolith shape analysis for stock discrimination of Trachinus draco (Trachinidae) in the Northern Tunisian waters (Raf-Raf and kelibia)

  
RouaidaMESSAOUD
IMPORTANCE OF OTOLITH MORPHOLOGY IN THE DISTINCTION OF TWO POPULATIONS OF LIZA AURATA IN TUNISIA: BIZERTE LAGOON AND LAKE ICHKEUL
 
Rouaida MESSAOUD1,
B. MARSAOUI 1, FATNASSI 1, M. TROJETTE 1 ; A. CHALAH 2 ; M. KHEDHER 1 ; M. REBAYA 1 ; B. MARSAOUI 1 ;  J-P. QUIGNARD 3 & M. TRABELSI 1

1 Unité des Biologie marine, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie
2 Unité de génétique des populations et ressources biologiques, Université Tunis El Manar, Tunis, Tunisie
3 Laboratoire d’Ichtyologie, Université Montpellier II, Montpellier, France
 
Abstract
Otoliths (the Greek oto: ear and lithos: stone) are mineralized concretions, located in the inner ear of fish. These stones were analyzed in this study to differenciate between two populations of Tunisian lagoons Liza aurata (Bizerte Lagoon and Lake Ichkeul).
Otoliths of each fish were collected, cleaned, photographed and processed by the software "PHOTOSHOP", "SHAPE" and "XLSTAT", respectively.
Statistical analyzes showed that:
- F1 axis between the two populations study (the population of the Bizerte Lagoon is located on the positive side while the Ichkeul occupies the negative part). The differences between these two populations are highly significant with p-value < 0.001 (value much lower than the significance level 0.05) where there is two distinct populations.
- F2 axis between otoliths rights are on the positive side of the left that are located on the negative side of the two populations studied. The differences are very significant between male otoliths rights taken from two stations studied, males left otoliths, otoliths rights of female and left otoliths females, respectively.
Keywords: Otoliths, Liza aurata, Bizerte Lagoon, Lake Ichkeul, Discrimination

marsaouibochra@gmail.comTheme II: Community indicatorsPosterIMPORTANCE OF OTOLITH MORPHOLOGY IN THE DISTINCTION OF TWO POPULATIONS OF LIZA AURATA IN TUNISIA: BIZERTE LAGOON AND LAKE ICHKEUL

  
RouaidaMESSAOUD
OTOLITHOMETRIC COMPARATIVE STUDY OF TWO TUNISIAN LAGOONS POPULATION OF LIZA AURATA (LAGOON GHAR EL MELH AND ICHKEUL)
 
Rouaida MESSAOUD 1,
B. MARSAOUI 1, FATNASSI 1, M. TROJETTE 1 ; A. CHALAH 2 ; M. KHEDHER 1 ; M. REBAYA 1 ;  J-P. QUIGNARD 3 & M. TRABELSI 1

1 Unité des Biologie marine, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie
2 Unité de génétique des populations et ressources biologiques, Université Tunis El Manar, Tunis, Tunisie
3 Laboratoire d’Ichtyologie, Université Montpellier II, Montpellier, France
 
Abstract
The study of otoliths is interesting in many ways. Including the analysis of their shape which allows the identification and discrimination of stocks. In this context, all otoliths were analyzed to compare the population of Liza aurata of lagoon of Ghar el Melh with that of the Ichkeul lake.
The results showed the existence of two different populations with very significant differences (p-value <0.001). Wilks test confirms this result.
The projection of otoliths of these two populations shows that F1 (Absorption = 63.91%) axis divides the population of Ghar el Melh which is the positive side of the Ichkeul which is the negative side.
 
Keywords: Otoliths, Liza aurata, Lagoon Ghar el Melh, Lake Ichkeul.

marsaouibochra@gmail.comTheme II: Community indicatorsPosterOTOLITHOMETRIC COMPARATIVE STUDY OF TWO TUNISIAN LAGOONS POPULATION OF LIZA AURATA (LAGOON GHAR EL MELH AND ICHKEUL)

  
Nour El HoudaMAHNOUCHI
OTOLITHOMETRY ASPECT OF DIFFERENTIATION OF TRACHURUS TRACHURUS (PERCIFORMES, CARANGIDAE) IN THE LAGOON OF BIZERTE AND THE ISLAND OF GALITE IN TUNISIA
Nour el houda MAHOUACHI 1,
F. MAAZI 1,2, B. MARSAOUI 1, M. FATNASSI 1, M. TROJETTE 1, M. KHEDHER 1, R. MESSAOUD 1, M. REBAYA 1, A. CHALAH 2, J-P. QUIGNARD 3 & M.TRABELSI 1
 
1 Unité de Biologie Marine, Faculté des Sciences, Université  Tunis El Manar, Tunis, Tunisie
E-mail: Nourelhoudamahouachi4@gmail.com
2 Unité de Génétique des Populations et Ressources Biologiques, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie
3 Laboratoire d’Ichtyologie, Université Montpellier II, Montpellier, France
 
Abstract
Horse mackerel (Trachurus trachurus) is a teleost belonging to the family Carangidae; which gathers in a pelagic bench on sandy bottoms, but sometimes the depth. This species is experiencing a wide geographical distribution populating the entire Atlantic, the Mediterranean basin including the Black Sea, the Pacific and even the Indian Ocean.
Otolithometric analysis is a technique widely used in the differentiation of species of fish and the discrimination of their stock in different environments. The saccular otolith or sagitae is the largest and most in diagnostic research.
This work aims to make the differentiate between Trachurus trachurus population of the Bizerte’s lagoon, located in the extreme north of Tunisia over an area of approximately 128 km ² with a maximum width of 11 km and a maximum length 13 km, compared with individuals from the island of la Galite, located in northwest of the Tunisian coast, measuring 5.4 km in length from east to west and up to 2.9 km width in its eastern part, by otolithometric approach to analyze the shape of the left and right otoliths.
The results obtained demonstrate the presence of a difference between males and females of both populations. This result allows assuming sexual dimorphism in otolith of Trachurus trachurus in the two media studied.
Keywords:Trachurus trachurus, Sagittae, Lagoon of Bizerte, Island of Galite, Tunisia.

marsaouibochra@gmail.comTheme II: Community indicatorsPosterOTOLITHOMETRY ASPECT OF DIFFERENTIATION OF TRACHURUS TRACHURUS (PERCIFORMES, CARANGIDAE) IN THE LAGOON OF BIZERTE AND THE ISLAND OF GALITE IN TUNISIA

  
Nour el houdaMAHOUACHI
APPLICATION OF OTOLITH SHAPE ANALYSIS IN IDENTIFYING DIFFERENT SPECIES OF ZOSTERISESSOR OPHIOCEPHALUS AND GOBIUS PAGANELLUS IN THE LAGOON OF BIZERTE IN TUNISIA

Nour el houda MAHOUACHI 1,
F. MAAZI 1,2, B. MARSAOUI 1, M. FATNASSI 1, M. TROJETTE 1, M. KHEDHER 1, R. MESSAOUD 1, M. REBAYA 1, A. CHALAH 2, J-P. QUIGNARD 3 & M.TRABELSI 1
 
1 Unité de Biologie Marine, Faculté des Sciences, Université  Tunis El Manar, Tunis, Tunisie
E-mail: Nourelhoudamahouachi4@gmail.com
2 Unité de Génétique des Populations et Ressources Biologiques, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie
3 Laboratoire d’Ichtyologie, Université Montpellier II, Montpellier, France

The two species of gobies Gobius paganellus (Linnaeus, 1758) and Zosterisessor ophiocephalus (Pallas, 1811), are very common in Mediterranean waters, they are easily identified by their pelvic fins which are usually welded along their entire length.
The analysis of otolith shape based on elliptic Fourier analysis (A.F.D.) followed by a statistical analysis is an excellent tool for discrimination of families, genus, species and even fish populations of the same species. In this context, the present study is to separate two species of gobies mentioned, living in sympatry in the Bizerte lagoon (northern Tunisia).
The results highlight the presence of net morphological differences between left and right otoliths of both species. Population of Z. ophiocephalus is located on the positive side of the axis F1 (absorption = 61.94%) and the population of G. paganellus is located on the negative side of the same axis F1. While F2 axis (absorption = 24.37%) separate, right and left otoliths and those of Z. ophiocephalus and G.paganellus.
Own calculated value is less than the significance level (p-value <0.05), or the presence of significant differences between these two populations. So we can conclude that there is no resemblance between these two populations living in the same lagoon environment.
 
Keywords: Sagittae, Gobius, Shape, Shape analysis, Fourier Analysis Elliptical.

marsaouibochra@gmail.comTheme II: Community indicatorsPosterAPPLICATION OF OTOLITH SHAPE ANALYSIS IN IDENTIFYING DIFFERENT SPECIES OF ZOSTERISESSOR OPHIOCEPHALUS AND GOBIUS PAGANELLUS IN THE LAGOON OF BIZERTE IN TUNISIA

  
MaissaKHEDHER
Otolithometric Comparative study of two Tunisian populations of Mugil cephalus: a population lagoon (Lagoon of Bizerte) and a marine population (Sea of Tabarka)

Maissa KHEDHER 1,
Manel FATNASSI 1, Mouna TROJETTE 1, Bochra MARSAOUI 1,
Manel REBAYA 1, Rouaida MESSAOUD 1,  Nour El Houda MAHOUACHI 1,
Abdellah CHALAH 2, Jean-Pierre QUIGNARD 3 & Monia TRABELSI 1
 
1 Unité de Biologie Marine, Faculté des Sciences, Université  Tunis El Manar, Tunis, Tunisie
E-mail: khedher.maissa@gmail.com
2 Unité de Génétique des Populations et Ressources Biologiques, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie
3 Laboratoire d’Ichtyologie, Université Montpellier II, Montpellier, France

The inner ear of fishes includes three otic fish bags which are: the sacculus, the utriculus and the lagena which contain the sagittea, the lapilus and astericus.
In most cases, the sagittea is considered the largest of the three limestone pieces, but also the first to appear during the formation of the larva; that is why this otolith is used in this work in order to compare two Tunisian populations of Mugil cephalus: population from Bizerte lagoon and sea of Tabarka.
The methodology is based on three steps; firstly, the removal and cleaning of otoliths, then the photography and the photo processing and finally the statistical analysis.
The results obtained allow us to illustrate the following conclusions:
The two populations are separated by the axis F2 (absorption = 18.46%); the marine population occupies the negative part of that axis (except the left otolith ♂ who is placed in the positive part), while that in the lagoon is located in the positive part.
Highly significant differences (p- value < 0.0001) are indicated at the otoliths pairs (G and D) of ♀ and ♂of the two stations where there is an asymmetry.
These results demonstrate the lack of similarities between the two lots arriving from the two backgrounds which confirm the existence of two different populations.
 
Keywords: Mugil cephalus, Otoliths, Sea of Tabarka, lagoon Bizerte, Tunisia

marsaouibochra@gmail.comTheme II: Community indicatorsPosterOtolithometric Comparative study of two Tunisian populations of Mugil cephalus: a population lagoon (Lagoon of Bizerte) and a marine population (Sea of Tabarka)

  
BochraMARSAOUI
USE OF THE CONTOUR SHAPE OF OTOLITHS IN THE DISCRIMINATION OF TWO BATCHES OF SEA BREAM (SPARUS AURATA) WILD AND FARMED FISH
 
Bochra MARSAOUI 1,
M. KHEDER 1, R. MESSAOUD 1, M. FATNASSI 1, M. TROJETTE 1, M. REBAYA 1, A. CHALAH 2, J-P. QUIGNARD 3 & M.TRABELSI 1
 
1 Unité des Biologie marine, Faculté des Sciences, Université Tunis El Manar, Tunis, Tunisie
E-mail: marsaouibochra@gmail.com
2 Unité de génétique des populations et ressources biologiques, Université Tunis El Manar, Tunis, Tunisie
3 Laboratoire d’Ichtyologie, Université Montpellier II, Montpellier, France

Otoliths are the first calcified formations that appear at the embryonic stage, these calcified have long been the subject of research on the biology of fish because they have the property of finely record the stages of growth of individuals during their life.
In this otolithometric study, Otoliths of Royal sea bream, sampled respectively from the sea of Bizerte and an aquaculture site in the Gulf of Hammamet (Ibn Khiar in Nabeul), were collected to illustrate the differences or the similarities between these two batches of fish.
Otoliths have been cleaned and photographed and the photos were, then, subjected to treatments of image by software (Photoshop/Shape) and multivariate statistical analyses.
Concerning indices of forms, the graph, representing the two batches of fish Otoliths, reveals the existence of two distinct populations (total absence of symmetry between wild and cultured populations) ; What is confirmed by statistical tests (the P-value < 0,0001, the Mahalanobis-distance test and confusion matrix etc…)
These results can be explained by the difference in living conditions (feeding, growth, habitat, etc…) of the two populations.

Keywords: Sparus aurata, Otoliths, farmed fish, wild, Ibn khiar, sea of Bizerte, Tunisia

marsaouibochra@gmail.comTheme II: Community indicatorsPosterUSE OF THE CONTOUR SHAPE OF OTOLITHS IN THE DISCRIMINATION OF TWO BATCHES OF SEA BREAM (SPARUS AURATA) WILD AND FARMED FISH

  
DanswellStarrs
Current techniques for examining the internal microstructure of otoliths can be slow and laborious, requiring the mounting and sectioning of otoliths prior to data collection. Computed X-ray Tomography (CT scanning) with modern, high resolution systems may facilitate the examination of otolith internal microstructures without the need for sectioning. This study aims to examine and compare the internal microstructure of the otoliths of multiple commercial Australian fish species using CT scanning, and traditional otolith sectioning and microscopy analyses. Future applications of CT scanning will be discussed, including the potential to examine otolith microstructure in situ, eliminating the need for otolith removal. This has implications for the management of rare and endangered fishes, and how biological data is collected for fisheries management.
The Australian National University

​Research School of Biology

Daley Road

​Canberra

0200Australia+61 2 6125 2879danswell.starrs@anu.edu.auTheme III: Population indicatorsPosterCan Computed X-ray Tomography (CT scanning) reveal otolith microstructure?

​techniques, ageing, microstructure, CT scanning

Marta Vidal-Garcia

Scott Keogh

  
DanswellStarrs
Mass-marking fish larvae can facilitate studies exploring connectivity and dispersal patterns of early life history phase fishes. Maternal injections of enriched stable isotopes can provide a means of mass-marking fish larvae during the embryonic phase, because the enriched stable isotopes become incorporated into the larval otoliths (transgenerational marking). However, this is a recent technique that has seen limited development and application. We explored the efficacy of transgenerational marking in the Purple-spotted gudgeon (Mogurnda adspersa) and Eastern rainbowfish (Melanotaenia splendida), and through a meta-analysis, evaluated the effects of this technique on larval fish morphology and growth across a range of marine and freshwater fishes. Transgenerational marking was highly effective, enabling mass-marking of larvae produced by adult females for up to 6 months post-injection. Multiple unique markers could be produced, with minimal impacts on larvae morphology, survival and growth. Our meta-analysis revealed minimal effects on marked larvae, suggesting that this technique may be applied to explore dispersal and connectivity in aquatic ecosystems.
The Australian National University

Daley Road

Canberra

0200Australia+61 2 6125 2879danswell.starrs@anu.edu.auTheme III: Population indicatorsPresentationMass-marking fish larvae via maternal transmission of enriched stable isotopes

​mass-marking, mass spectrometry, enriched isotopes, dispersal, connectivity

Brendan C. Ebner

Stephen M. Eggins

Christopher J. Fulton

  
Ole ThomasAlbert
Greenland halibut is difficult to age, and there are no commonly agreed ageing protocol although a recent ICES workshop considered two recently developed methods as promising. Especially the mid-age (age 5-10) sequence of zones are considered highly uncertain and stock assessments are much in need of resolving the issue. During 2006-2008 several thousand juvenile Northeast Arctic Greenland halibut were tagged and injected with oxytetracycline (OTC), a compound that remains in the blood for 1-2 weeks and incorporates in calcified tissue produced during this period, making a visible time stamp in the otoliths just after release. The fishes were released in the nursery area north of Svalbard and recaptured in both the Barents Sea and in Faroese and Icelandic waters. More than 40 recaptures that had been at large for 1-6 years were returned with their otoliths in place. Otolith growth incremments from the periods at large were analysed with respect to zonation pattern and increment width. Results were discussed in relation to somatic growth increment, sex and recapture area. Based on the results, a modified ageing protocol is suggested.
Institute of Marine Research

​Tromsø

9294Norway0047 99626002oleta@imr.noWorkshop on age validationPresentationValidation of annual zones in Greenland halibut otoliths from recaptures of chemically marked fish

​validation, OTC, Greenland halibut, age

  
AntonioCalò
Fish larvae at competency stage (i.e. when they are ready to settle) can display considerable behavioural and movement capacity potentially influencing their spatial and temporal patterns of settlement and distribution in coastal habitats. With the aim to provide insights about the occurrence and the extent of behaviourally-mediated settlement delay, considered as a proxy of behaviourally mediated processes, we investigated the spatial variability of larval phase duration in the saddled sea bream Oblada melanura during the competency phase (considering near-settlement and early post-settlement individuals). To accomplish this task we analysed otolith micro-structure. Days after hatching (DAH) in pre-settlers and pelagic larval duration (PLD) in post-settlers were analysed in 2 zones (each corresponding to ~20 km of coastline ) separated by ~100 km, along the coast of the region of Murcia (Spain, West Mediterranean Sea). DAH was, on average, ~2 days shorter than PLD. The overall variability of PLD was found to be statistically higher than DAH variability. No significant variability was detected for DAH at the spatial scale considered, where PLD was found to vary significantly. The outcomes of this study suggest that the competency phase could be affected, more than earlier larval stages, by processes able to 1) influence PLD variability and 2) determine a delay during the selection of suitable settlement habitats. This information could have crucial implications for the development of more accurate models of larval dispersal.
University Of Murcia

​Campus Espinardo

​Murcia, Murcia

30100Spain+34 868884326antonio.calo@um.esTheme III: Population indicatorsPresentationCOMPETENCY PHASE AFFECTS PATTERNS OF FISH EARLY LIFE TRAITS

Competency phase, Early life traits, Sea bream, Mediterranean Sea

​Antonio Di Franco, Paolo Guidetti, José Antonio García-Charton

  
LygiaRuas
​​​The rough scad, Trachurus lathami, is an important resource for purse seine fisheries in the Southwestern Atlantic Ocean, including the Brazilian coast. Particularly since 1994 its landings decreased a lot, lower to 1,000 tons, after periods of almost 8,000 tons/year. The last estimates available about the age and growth of the species date back to the 1970s. In order to update this information, samples obtained through hydroacoustic surveys along the continental shelf (22ºS-29ºS) between 2008 and 2010 were analyzed. An otolith subsample (10%) of the 1,312 individuals (total length between 27 and 208 mm) obtained was selected and, following the pre-established methodology for the species, digital images of whole otoliths were submitted to three blind readings. The rings were counted and measured from the nucleus to the beginning of a translucent zone, following the posterior axis. The border, whether it was opaque or translucent, was also recorded. A total of 131 saggitae were analyzed, containing up to seven rings. The second one was not considered as an annual ring and its occurrence has never been reported yet, deserving further investigation. The VBGF parameters were fitted by the nonlinear iterative least square method using all lengths available, resulting in L∞=230.69mm, K=0.260year-1 and t0=-0.693years. The age of all individuals of the sample (n=1,312) varied between zero and eight years, mainly constituted by fish which were three (42%) and four (27%) years old. Average lengths regarding age (into brackets) were: 38mm (zero), 82mm (one), 116mm (two), 142mm (three), 162mm (four), 178mm (five), 190mm (six), 199mm (seven) and 206mm (eight). The results show that the age structure and growth of the T. lathami remains similar to that previously described and this is the most recent data for the rough scad in the Southwestern Atlantic.
Universidade Federal do Paraná

Laboratório de Esclerocronologia. ​Rua Pioneiro, 2153 Jardim Dallas

​Palotina, Paraná

85950-000Brazil55 44 3211-8597andrevaz@ufpr.brTheme III: Population indicatorsPosterUpdating the age and growth of the rough scad, Trachurus lathami Nichols, 1920 in the Southwestern Atlantic
annual rings, age structure, von Bertalanffy growth function​, average length

André M. Vaz-dos-Santos​

  
Ashley JohnWilliams
Deepwater fisheries in tropical and sub-tropical regions of the Pacific Ocean are typically small-scale artisanal and subsistence fisheries, with strong local economic and cultural value in many Pacific Island countries. Deepwater snappers (Subfamily Etelinae) are the main species targeted by these fisheries which provide an important source of protein to Pacific Island countries that are highly dependent on fish for food security. Most species of deepwater snapper are considered vulnerable to exploitation due to their extended longevity (>40 years) and low mortality rates. However, the sustainability of deepwater snapper fisheries in Pacific Island countries remains uncertain because there are limited resources available to collect the required data for comprehensive stock assessments. Reliable estimates of age composition for exploited deepwater snapper populations are lacking primarily because of the lack of skills and resources required for routine age estimation from sectioned otoliths. Development of alternative low-cost approaches to derive estimates of age for deepwater snapper is required. We evaluate the performance of using otolith morphometrics (weight, length, width and thickness) and fish length to obtain estimates of age for the most important target species in these fisheries: Etelis carbunculus, E. coruscans, E. marshi and Pristipomoides filamentosus. We then compare age compositions and fishing mortality rates (F) derived from otolith morphometrics with those derived from counts of annual increments in otoliths for each species. In the absence of sufficient resources to section otoliths for age estimation, we propose that otolith morphometrics are used as a proxy for age in F-based assessments of deepwater snapper fisheries in Pacific Island countries.
Oceanic Fisheries Programme, Secretariat of the Pacific Community

95 Promenade Roger Laroque, Anse Vata

​Noumea

98848New Caledonia+687 262000ashleyw@spc.intTheme III: Population indicatorsPresentationAssessment of otolith morphometrics as proxies for age in F-based assessments of tropical deepwater fisheries

​otolith morphometrics, age estimation, deepwater snapper, Pacific Ocean, artisanal fisheries, Etelis, Pristipomoides

Stephen J. Newman

Corey B. Wakefield

Simon J. Nicol

Melanie Bunel

  
StevenCampana
Past attempts to age Deepwater Redfish (Sebastes mentella) and Acadian Redfish (S. fasciatus) have been stymied by ad hoc and/or invalid ageing methods, the absence of age validation, and the failure to differentiate among species. Here we report substantial improvements in the tried and true “break and burn” method for ageing Sebastes spp through modern sectioning and image enhancement protocols. Otolith halves sectioned with an Isomet saw allowed routine preparation of completely flat surfaces for charring, while imaging and image enhancements significantly improved the visibility of narrow annuli in older fish. Bomb radiocarbon assays of the otolith core confirmed the accuracy of the resulting age determinations. The use of microsatellite DNA to confirm species identity eliminated past confusion due to species mixtures. Age determinations of 1249 redfish from the eastern coast of Canada demonstrated the presence of significant differences in growth rate and longevity both between the two redfish species and among stocks, with a maximum observed longevity of 70 yr. Even within species and stocks, an individual fish with a fork length of 38 cm could be anywhere between 15 and 50 years of age, highlighting a near cessation of somatic growth after sexual maturation. The presence of annulus splitting in many old S. fasciatus rendered some age interpretations virtually impossible, demonstrating that even modern ageing methods cannot provide accurate age determinations in all circumstances.
Bedford Institute of Oceanography

​1 Challenger Drive​

​Dartmouth, NS

B2Y 4A2Canada902-426-3233steven.campana@dfo-mpo.gc.caTheme III: Population indicatorsPresentationImage-enhanced burns, bomb radiocarbon and microsatellite DNA improve the accuracy and precision of otolith-based age determinations for redfish (Sebastes spp)

​age determination, annuli, age validation, bomb radiocarbon, crack and burn, otolith, Sebastes

​Alexandra Valentin

Jean-Marie Sevigny

Shayne MacLellan

Joanne Groot

Darlene Gillespie

Judy McArthur

  
Jan-Olof Lill
European whitefish (Coregonus lavaretus) exists in two sympatric forms in the northern Baltic Sea; an anadromous river spawning and a sea spawning form. The groups form mixed populations outside breeding time and place. The river spawning whitefish in the northern Baltic Sea has diminished mainly due to anthropogenic destruction of the spawning rivers and the conditions in them, and is presently listed among endangered species on the HELCOM red list of Baltic Sea species in danger of becoming extinct (BSEP 140) and as a globally vulnerable species on the IUCN red list of threatened species. Methods for whitefish identification are a prerequisite for a sustainable management of the fish stocks. However, river spawning whitefish cannot be distinguished from sea spawning whitefish based on outer morphology, and alternative methods are therefore searched for. In this work we describe an application of particle-induced X-ray emission (PIXE) to the elemental analysis of polished otoliths of whitefish. Two spot on polished otoliths were irradiated; one spot in the centre of the otolith and one in the periphery. The irradiations were performed in air with a collimated 0.5 mm proton beam. The ratio of the strontium concentrations in the two spots was used to distinguish between the different groups of whitefish. Criteria on the ratios were suggested for identification of the whitefish groups. The results were compared to results of µ-beam PIXE scans as well as multi-point scans with the 0.5 mm proton beam. The measuring set-up and the results are discussed.
Accelerator Laboratory, Turku PET Centre, Åbo Akademi University

Porthansg. 3

​Turku

FI-20500Finlandjlill@abo.fiTheme IV: Individual indicatorsPosterTwo-spot PIXE analyses of polished otoliths for identification of anadromous whitefish in the Baltic Sea

Otolith, strontium, whitefish, Baltic Sea, PIXE

Mikael Himberg, Joakim Slotte, Yvette Heimbrand, Ann-Britt Florin, and Henry Hägerstrand

  
MiguelAraya
Partial migration, the incidence of opposing migration behaviors within the same population, has been a key factor in the invasive ecology of Pacific salmon within South America. Here, we examined such life-cycle variation in of an introduced chinook salmon population in the Aysén watershed, one of the largest fjord systems in NW Patagonia. The chinook salmon is the most successful invasive salmonid species in Patagonia and has recently colonized numerous Patagonian watersheds of the Pacific and Atlantic Oceans. Using analyses of fish scales and otolith strontium:calcium ratios, our results suggest the presence of two distinct ecotypes in the chinook population, an ocean type and a stream type, in a 3:2 ratio. The distribution of back-calculated length at the time of emigration from river to marine habitats showed a mode of 14 cm for the ocean ecotype and 30 cm for the stream ecotype. River residence time for the ocean ecotype ranged from 1 to 10 months, while that of the stream ecotype varied between 14 and 20 months. Returning adults reproduced in riverine habitats between August and March, but reproduction by the stream ecotype was limited to the period between October and February. Our results show that exotic chinook salmon populations established in NW Patagonia present a diversity of life-history strategies, which seems to be as large as the ones exhibited by the species in its native distribution range and in other invaded ecosystems. Studies are needed of the cycles of life among chinook salmon in the Aysén watersheds and other invasive populations of chinook salmon, and their impacts on the invaded ecosystem.
Arturo Prat University

University of Antofagasta, Doctorate Program in Applied Sciences: Coastal Marine Systems. Antofagasta, Chile.

Present address: Arturo Prat University, Faculty of Renewable Natural Resources.  P.O.Box 121.

​Iquique, I región, Tarapacá

1110939Chilemaraya@unap.cl; miguelaray@gmail.comTheme III: Population indicatorsPosterPartial migration in introduced wild chinook salmon (Oncorhynchus tshawytscha) of southern Chile

Introduced species; life-history variation; otoliths microchemistry; partial migration; Sr:Ca

Miguel Araya (1), Edwin J. Niklitschek (2), Dave H. Secor (3) & Philip M. Piccoli (4)

(1) University of Antofagasta, Doctorate Program in Applied Sciences: Coastal Marine Systems. Antofagasta, Chile.

Present address: Arturo Prat University, Faculty of Renewable Natural Resources.  P.O.Box 121. Iquique, Chile. maraya@unap.cl

(2) University of Los Lagos, i~mar Research Centre. Puerto Montt, Chile. edwin.niklitschek@ulagos.cl

(3) University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory. PO Box 38, Solomons, MD 20688, USA. secor@umces.edu

(4) University of Maryland, Department of Geology. College Park, MD 20742, USA. piccoli@umd.edu

  
Louise Rutterford
Several North Sea fish stocks are characterised by geographically discrete sub-populations, which will each experience uniquely different local environmental conditions. Recent studies indicate that some North Sea species may relocate to track preferred temperatures in warming seas, but emerging research suggests distributions can be constrained by depth or oceanographic features meaning that fish are consequently exposed to warmer conditions. The impacts of warming on sub-populations of targeted species should thus be an important consideration when determining how fisheries are managed into the future. Using analysis of otolith growth patterns and size-at-age data from fisheries surveys, we will examine sub-population specific responses of plaice and cod to warming seas in recent decades, and gauge the level to which stock subdivision modulates predicted impacts of warming climate. Findings from this research will help to identify whether sub-populations have differing capacities to respond to warming; a factor largely overlooked in existing studies of marine environmental change.
University of Exeter

​15 Chessel Street

​Bristol

BS3 3DPUK07786562651lar210@exeter.ac.ukTheme III: Population indicatorsPosterUsing otoliths to gauge sub-population responses to warming seas

​Otolith, North Sea, sub-populations

​Ewan Hunter

  
JorgeLanda
To confirm the consistency of the age interpretation by validation studies is essential for providing accurate age estimates to the stock assessment process using age-structured models.
The Atlantic Iberian megrim (Lepidorhombus whiffiagonis) stock is annually assessed by age-structured models in ICES, and specimens are routinely aged by IEO expert readers for this purpose. A total of 8845 otoliths of this stock were aged from 23 annual groundfish surveys carried out in north and northwestern Iberian waters (ICES Div. VIIIc, IXa) and following internationally standardized protocols. Yearly age-length-keys were built using the respective age estimates and applied to the length distribution of each survey, thus obtaining a matrix of abundance indices by age and year. Similar mean lengths are obtained for each age group along the time series. The annual age estimation of L. whiffiagonis is here indirectly validated or corroborated by tracking cohort abundance indices in the surveys. Strong and weak cohorts are well tracked along the most of their age classes, and the correlations between age abundance indices are statistically significant up to the age 5, which represent around 94% of the total number of this species caught in the surveys. The von Bertalanffy growth parameters for the time-series are estimated (L∞: 56; k: 0.12; t0: -1.88) and the results are compared with previous studies.
Instituto Español de Oceanografía (IEO). Centro Oceanográfico de Santander

Promontorio San Martín, s/n. ​

Santander​

39004Spain.942.29.17.16jorge.landa@st.ieo.esWorkshop on age validationPosterAge estimation of megrim (Lepidorhombus whiffiagonis) corroborated by cohort tracking in northern Iberian waters

Age estimation; otolith; growth; megrim; Lepidorhombus whiffiagonis; groundfish surveys; northeast Atlantic; northern Spanish shelf.  ​

Jorge Fontenla

  
SvenStöera
In the Baltic Sea, cod spawn in several basins that are separated by shallow sills. However, biological and management units of the two cod stocks do not match with the spawning grounds, causing constant concerns about mixing dynamics between ICES-Subdivisions (SD). Recently, Eastern Baltic cod displayed signs of recovery suggesting a spill over into the west. Basin-specific hydrographic conditions are reflected in optical differences and difficulties in age determination of Baltic cod otoliths, which may assist in evaluating the dynamics of mixing. We used 83 000 sliced and quality-flagged cod otoliths (readability categories: legible, uncertain or non-readable), collected from research surveys and commercial samplings of 2007 - 2013 covering ICES-Subdivisions SD21-29 to test the hypothesis of stable proportions of readability categories in time and space. The overall distribution of quality flags showed that the Darß and Drogden sill consistently separated large proportions of legible otoliths in the west (SD21-23) from large proportions of uncertain and non-readable otoliths in the east (SD25-29). SD24 clearly was a mixing area, however, strongly resembling SD25 and not SD22 or SD23. The relative distribution of quality flags only showed minor and inconsistent changes without significant trends in a multinomial logistic regression (grouped by all fishes, sex or length class), irrespective of the spatial (SD, rectangle, quarter-rectangle) and temporal scale (year, quarter). Instead, stable distribution patterns with about 3-5% of non-readable otoliths in SD22 and about 7-10% of legible otoliths in SD25 suggested stable mixing dynamics over time since 2007. The lack of increased proportions of unreadable otoliths in SD24 did not support a spill over from the east. However, the large proportion of uncertain otoliths in SD24 may mask the detection of mixing trends. The relationship between life history pattern of individual cod and quality flag category of their otolith are not yet understood.
Thünen Institute for Baltic Sea Fisheries

​Alter Hafen Süd 2

​Rostock

18069Rostock+493818116123sven.stoetera@ti.bund.deTheme III: Population indicatorsPresentationUse of otolith quality flags to assess distributional dynamics in Baltic cod stock

Gadus morhua; Baltic Sea; quality flags; otolith; readability; stock dynamics; mixing; spill over

Uwe Krumme​

  
MarkEtherton
We use the age of dab (limanda limanda) to determine if exposure to contaminents at particular locations affects the cancer rates observed in individuals or if it is simply a surrogate for age. We observed the age at onset of cancer is accelerated at certain locations. Areas can be assessed against a naional baseline and can be used for monitoring the health of the sea and comparing regions over time.
Cefas

​Pakefield Road, Lowestoft

​Suffolk

NR33 0HTUK01502 524539Mark.Etherton@cefas.co.ukTheme II: Community indicatorsPosterUsing age to determine cancer onset rates in dab (Limanda limanda) in UK waters

​Age, otolith, cancer, limanda limanda

G.D. Stentiford, ​J. Bignell, B.P. Lyons, J.E. Thain, S.W. Feist

  
MarkEtherton
Patagonian toothfish are an important species for fisheries in South Georgia and the South Sandwich Islands. Management measures rely on understanding population dynamics, including age and growth rates. We determine an optimal methodology for age estimation and validate our age data via the extensive tagging programmes undertaken in recent years.
Cefas

Pakefield Road, Lowestoft​

Suffolk​

NR33 0HTUK01502 524539mark.etherton@cefas.co.ukTheme III: Population indicatorsPresentationInvestigations into the age determination and validation of patagonian toothfish (Dissostichus Eleginoides) from British Overseas Territories

​Patagonian toothfish, dissostichus eleginoides, age validation, otolith, tagging

  
JeanMartin
We aimed at assessing the dispersal capacity of Allis shad, an anadromous clupeid in decline throughout its distribution range. Colonization of new environments by shad is achieved via straying behavior, framed as failure to home, a fundamental life-history trait present in various proportions in anadromous fish populations. Geochemical signatures recorded in otolith were chosen to identify natal origin of 410 spawners caught at spawning grounds along the Atlantic coast from northern France to Portugal. However, as juveniles display a short freshwater residence time, a specific laser ablation strategy was required to target precisely the two weeks after hatching on the otolith. A novel UV high-repetition-rate femtosecond laser ablation device was deployed, permitting ablation of 60 µm thick coronas around otolith primordium, while avoiding any maternally-derived material accreted at the core. Otolith and water samples were analyzed for Sr:Ca, Ba:Ca, Li:Ca and 87Sr:86Sr ratios using a High Resolution ICPMS and a Multi-collector ICPMS. The allocation of natal origin was obtained from different sources of information (water chemistry, signatures in otolith of juveniles and spawners) within a Bayesian hierarchical mixture model. The chief advantage of this method over frequentist approaches was to exploit the relationship between water and otolith signatures, providing otolith chemistry to be predicted, with a mean classification accuracy of 86%, even for rivers where juveniles were unavailable. Results showed that 35% of adults displayed a straying behavior, mostly originating from neighbouring rivers. The proportion of strayers differed between source populations. Among the seventeen sampled locations, only three acted as a source population supplying adults to adjacent or distant sites. The southernmost population displayed the highest dispersal potential and 18 individual fish from this population strayed up to 1800km to the northernmost French river. Neither total length at maturity nor sex did determine the spatial scale over which straying occurred.
IRSTEA

Aquatic Ecosystems and Global Changes Research Unit

50, avenue de Verdun

​CESTAS

33612France33618630458jean.martin@irstea.frTheme III: Population indicatorsPresentationDispersal capacities of Allis Shad (Alosa alosa) under global change: insights of innovative otolith microchemistry analysis

Dispersal, Homing, Strontium isotopes, Allis shad, laser ablation

​Daverat Françoise, Jatteau Philippe, Rochard Eric, Bareille Gilles, Pecheyran Christophe, Bérail Sylvain, Feunteun Eric, Micaela Mota, David Clavet, Laurent Carry

  
TiffanySih
Pre-settlement processes that determine where and when a larval coral-reef fish will settle can have import implications not only individual survival, but also population distributions and abundances. However, many key factors, such as how long returning larvae spend close to reefs prior to settlement, are poorly understood. This study combined field and laboratory studies, coupled with laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) and otolith microstructure analysis (daily increments and settlement marks) to determine the length of time larval fish spent near a reef prior to settlement. The otoliths of Ambon damselfish, Pomacentrus amboinensis, collected from multiple neighbouring reefs in the southern Great Barrier Reef, showed clear differences in their elemental signatures prior to, and following, settlement. However, individual profiles also revealed substantial variation, with an increased otolith Ba:Ca ratio (near-reef signature) occurring right at settlement in some individuals, but up to 8 days prior to settlement in others. Increment widths, often used as a proxy for growth, decreased approaching the settlement mark. Differences in otolith elemental chemistry were also found between fish kept in Lagoon (reefal) and Ocean (inter-reefal) waters, however, these differences did not reflect the highly variable elemental composition of water sampled from each location. Poor discrimination of multi-element signatures was observed among fish from different reefs pre-settlement, but discrimination improved in the post-settlement phases of otoliths. This study demonstrated clear and consistent near-reef elemental signatures in fish around the time of settlement. We suggest these differences are due to a combination of water chemistry and physiological influences (i.e. feeding). Combining LA-ICP-MS with otolith microstructure analysis can provide high resolution information on the early life history of reef fishes.
ARC Centre of Excellence for Coral Reef Studies and James Cook University

​School of Marine and Tropical Biology

James Cook University

​Townsville, QLD

4811Australia+61(4) 1254 5060Tiffany.Sih@my.jcu.edu.auTheme I: Environmental indicatorsPresentationNear-reef elemental signals in the otoliths of Pomacentrus amboinensis (Pomacentridae)

Pomacentrus amboinensis, otolith microchemistry, near-reef signature, settlement, LA-ICP-MS

​Michael J. Kingsford

  
GillesBareille
Otolith chemistry has emerged as a useful tool for determining migration patterns, nursery habitats and natal origins of anadromous and freshwater fishes. The accuracy of this tool largely depends on the implicit assumption that the chemical signature of the otolith reflects the geochemical signature of the water in which the fish resides. Numerous studies have established direct correlation between environmental exposure and otolith chemistry especially for Sr:Ca and Ba:Ca ratios but only for a short period of time in the life of fish. However, ontogenetic changes in physiology, environmental variations, or movements may have been confounded as elemental incorporation dynamics may vary depending on the life history stage of the fish. Thus, endogenous control must be taken into account when interpreting life history transects across otoliths. The current study combined otolith chemistry profiles from known life-history juveniles of Atlantic salmon (Salmo salar) (hatchery-reared, field-collected) and geochemical water database to investigate the extent to which Ba:Ca and Sr:Ca variations are associated to the ambient water chemistry or not. This study aimed at improving the interpretation of field-based studies during freshwater residency. The results revealed that Ba:Ca ratio in otoliths was not always determined by its respective metal:Ca ratio in the ambient freshwater. Indeed, Ba:Ca otolith profiles were characterized by some peaks which could not be explained by chemical changes in the ambient water environment. These peak patterns were first observed at the yolk sac absorption mark but also when fish was moved from a hatchery to a river as well as following the smoltification event. At the yolk sac absorption mark, both wild-caught and hatchery-reared juveniles exhibited a Ba:Ca peak pattern, followed by a long tail-off until ratio remained stable and related to ambient water. We suggested that physiological processes are largely involved in the complex response of otolith Ba:Ca ratio.
Laboratoire de Chimie Analytique Bio-Inorganique et Environnement (LCABIE) UMR CNRS/UPPA 5254 University of Pau

Hélioparc Pau Pyrénées - 2, avenue du Président Angot

​PAU

64 053 Cédec 9FRANCE00 33 559 407 761gilles.bareille@univ-pau.frTheme III: Population indicatorsPresentationDoes Ba:Ca and Sr:Ca ratios always reflect ambient water composition where Atlantic salmon (Salmo salar) inhabits?

Otolith chemistry; Barium and Strontium; Atlantic salmon; Field and experimental studies

Bareille G.1*, Martin J.2, Pécheyran C.1, Bérail S.1, Aymes3 J.-C., Tabouret H.1, Daverat F.2, Holub A.1

1 Laboratoire de Chimie Analytique Bio-Inorganique et Environnement (LCABIE), UMR CNRS-UPPA 5254 IPREM, Hélioparc Pau Pyrénées, 64053 Pau, France (gilles.bareille@univ-pau.fr, christophe.pecheyran@univ-pau.fr, sylvain.berail@univ-pau.fr, helene.tabouret@univ-pau.fr, alexandre.holub@univ-pau.fr )

2 IRSTEA, Estuarine Ecosystems and Diadromous Fish Research Unit, 50 avenue de Verdun, 33612 Cestas Cedex, France (francoise.daverat@irstea.fr, Jean.Martin@irstea.fr)

3Institut National de la Recherche Agronomique, 64 310 Saint Pée Sur Nivelle, France (jcaymes@st-pee.inra.fr)

  
AndréVaz-dos-Santos
Araçá Bay is a complex coastal subtropical ecosystem (23°48'47,3"S 45°24'22,1"W) of Brazilian coast, constituted by different marine environments and subject to a lot of human impact. The Bay was selected for an ecosystemic study and its ichthyofauna was sampled seasonally (Oct-2012 to Jan-2014) employing eight different fishing gears.The most abundant species were Eucinostomus argenteus (23<Lt
Universidade Federal do Paraná
Laboratório de Esclerocronologia
Rua Pioneiro, 2153
Jardim Dallas​

​Palotina, PR

85950-000Brazil55 44 3211-8597andrevaz@ufpr.brTheme III: Population indicatorsPosterDo otoliths express the polyphasic growth of the main species in a coastal subtropical ecosystem?

otolith length, total length, allometry, Huxley model.

Bárbara Gris

Milton Ramos Pereira-Junior

Aline Giombelli-da-Silva

Angélica Arruda Justino

  
KarinLimburg
The Baltic Sea has experienced variations in its salinity and temperatures over its ca. 8000 year existence, due to climatic factors such as warming and cooling periods as well as to intrusions of North Sea water or retreats due to post-glacial isostatic rebound. We examined cod otoliths and vertebral bones from five periods: two periods in the Neolithic Age (4400–3800 y.b.p.), Iron Age (1000 y.b.p.), latter 1600s (Sweden’s Empire Period), and modern collections from periods with low (1990s) and high (2000s) hypoxia. 87/86Sr was quantified to fix salinities, and then 18O was used to determine temperatures during those time periods.
State University of New York College of Environmental Science and Forestry

​1 Forestry Way

​Syracuse, NY

13210United States+1.315-470-6741klimburg@esf.eduTheme I: Environmental indicatorsPosterPaleo- and modern salinity and temperatures as recorded by Baltic Sea cod Gadus morhua over millennia

​Baltic Sea; cod; salinity and temperature reconstruction; vertebrae vs. otolith chemistry

​Carina Olson

  
KarinLimburg
Otoliths are valuable for scientific research. Yet they also possess a kind of beauty. Visualization of otolith chemistry via 2-D trace elemental mapping can also produce interesting and appealing images. This project, intended as an art book, will extend my science as art for a broad audience, whether scientists or not. Through focusing on a number of fish species from different parts of the world, with different life histories and ecology, I will let otoliths "speak" to reveal the "tales" of fishes.
State University of New York College of Environmental Science and Forestry

​1 Forestry Drive

​Syracuse, NY

13210United States+1.315-470-6741klimburg@esf.eduTheme I: Environmental indicatorsPosterFish Tales Through Fish Ears

​otoliths as objects d'art

  
YoussefEL HABOUZ
In this paper we present an automatic classification system of fish species based on otolith contour analysis. Otolith has a distinctive external form which is usually a characteristic of the species. The external shape of the Otolith varies according to species, but it’s substantially constant in the same species. This can be used as a characteristic of fish species recognition. Identification of fish species using Otoliths is a major issue in many marine ecological studies. For example, the Otoliths recovered from the stomach or feces could be used to determine the food spectrum. The proposed system consists of three main phases: pre-processing, feature extraction and classification. The first phase is the image denoising and enhancing grayscale contour to facilitate the detection and contour extraction. In the second phase, we extract the median distance vector of the contour. This vector is used in Otolith recognition phase, which is based on the Support Vector Machine (SVM) classification method. The system was tested on a set of 60 fish Otolith images from AFORO database, 10 images per species for six species (Scomber colias, Coris julis, Umbrina canariensis, Diplodus annularis, Trachurus mediterraneus and Trisopterus minutus). The experimental results show the robustness of the approach (98.33%).
University Ibn Zohr

BP 32/S ,AGADIR,80000,Morocco

​​AGADIR

80000Morocco00212676114145elhabouzyoussef@gmail.comWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPresentationOtolith identification system based on image contour analysis

Otoliths, Fish, Species, AFORO, Image, Contour, Median distance, Recognition, Classification, SVM.

Y. ES-SAADY1, M. EL YASSA1, D. MAMMASS1,

F.NOUBOUD2, A. CHALIFOUR2

1 IRF-SIC Laboratory, University Ibn Zohr,

Agadir, Morocco,

elhouzyoussef@gmail.com, y.essaady@uiz.ac.ma, melyass@gmail.com, mammass@uiz.ac.ma

2LIRICS, University à Trois-Rivières,
Québec, Canada.

fathallah_nouboud@uqtr.ca, alain_chalifour@uqtr.ca​

  
Alejandra VaninaVolpedo
The marine catfish Genidens barbus is an anadromous species found in South America. The objectives of the present study were to evaluate a new method consisting in the partial polishing and analysis of the microchemistry of the lapilli as indicator of the habitat of G. barbus and identify the potential breeding areas and fish stocks between the populations from the lower section of the Plata Basin (De la Plata River estuary-Argentina) and Lagoa dos Patos coastal lagoon (southern Brazil). Sr:Ca, Ba:Ca and Mg:Ca ratios were measured in the core area (inner 4 rings) and external area (outer 3-4 rings) of the otoliths by ICP-OES. The Sr:Ca ratio tended to be higher in the otolith external area than in the core area, while the Ba:Ca ratio followed the opposite pattern, suggesting the moving towards areas of higher salinity. The results show significant differences (p<0.05) in the Sr:Ca, Ba:Ca, Mg:Ca ratios in the core and external area of otoliths from the Plata Basin and those from Lagoa dos Patos that may indicate the occurrence of at least two different breeding sites and suggests the occurrence of at least two fish stocks in the region.
Instituto de Investigaciones en Producción Animal (INPA-CONICET-UBA)/Centro de Estudios Transdisciplinarios del Agua (CETA-UBA), Facultad de Ciencias Veterinarias, Universidad de Buenos Aires /Instituto de Oceanografia, Fundação Universidade Federal do Ri

Av. Chorroarín 280 (C1427CWO), Buenos Aires, Argentina./

Buenos Aires, Argentina

1427Argentina/Brasilavolpedo@gmail.comTheme I: Environmental indicatorsPosterUse of lapillus otolith microchemistry as indicator of the habitat of Genidens barbus in different estuarine environments from the southwestern Atlantic Ocean.

anadromous fish; Genidens barbus; lapilli otolith; microchemistry

Esteban Avigliano, Gonzalo Velasco

  
SatoshiKatayama
Alternative formations of opaque and translucent zones in the otolith are widely used for age determination. However, the mechanisms causing annual periodicities in these zone formations is unknown, so there have been various interpretations and explanations concerning the appearance of opaque zones.
In the previous symposium, our group reported two types of opaque zone with quite different structures. Further studies were performed to understand the characteristics of these opaque zones, using otoliths from various fishes. It was found that the structural heterogeneity can actually be classified into four (rather than two) types of opaque zone.
Type A: A dark opaque zone, displaying minute, dense crystals, typically formed at younger ages.
Type B: A washy black zone, which has the appearance of being smeared with ink, formed during seasons of active growth.
Type C: An aggregation of grooves and discontinuous crystals formed during growth-stagnant periods.
Type D: A deep groove, appearing luminous in transmitted light in etched otolith sections, formed during the spawning season.
Otolith zones of types A and B are typical in younger fish and during the growing season, apparently complementary to types C and D. The latter are formed during periods of stagnant growth and/or spawning seasons and are more typical of older fish, in which type A is absent. To be certain of precise age determination, it is necessary to understand the structural and biological characteristics producing these four distinct types of opaque zone.
Tohoku University

​1-1 Amamiya-machi, Tsutsumidori, Aoba-ku

​Sendai

981-8555Japan 81-22-717-8728skata@m.tohoku.ac.jpTheme IV: Individual indicatorsPosterFour types of otolith opaque zone

Structure, Growing reason, Spawning season

Ian G. Gleadall and Kumiko Ito

  
SkyeWoodcock
The effectiveness of otoliths to recreate environmental histories of fish has led to the expansion of analytical techniques to other calcified structures of fish which allows comparisons between structures, as well as different organisms, such as corals and molluscs. Cuttlefish have two primary calcified structures, statoliths, which are the equivalent to otoliths in fish, and the cuttlebone, an aragonite structure used for buoyancy. Laboratory studies have shown statoliths reflect chemical changes in the surrounding environment, similar to otoliths, but similar studies have not been undertaken on cuttlebones. This study investigated whether statoliths and cuttlebones could be used to trace movements and connectivity of the largest cuttlefish species in the world, the giant Australian cuttlefish Sepia apama. We aim to determine the presence of a natal signature from pre-hatch embryos collected from an 8 kilometres stretch of a sub tidal rocky reef in the northern Spencer Gulf, South Australia, where this species is known to aggregate annually to breed, by analysing statolith chemistry using laser ablation inductively coupled plasma-mass spectrometry and then comparing patterns to the chemical signatures of returning adults. Furthermore we aim to quantify if the chemical signatures are analogues between the otolith and cuttlebone structure. Chemical profiles will be used to determine if cuttlefish have dispersed from a common source population (the aggregations site) as well as determine the variability in environments they have moved though throughout their lives. This study will help to identify the percentage of aggregating adults which returned, or have come from different breeding areas thereby allowing for better management and protection of the population.
The University of Adelaide

Southern Seas Ecology Laboratories

Darling Building DX 650 418

School of Earth and Environmental Sciences

The University of Adelaide, 

5005Australia+61 8 8313 6067skye.woodcock@adelaide.edu.auTheme I: Environmental indicatorsPresentationNatal signatures in the calcified structures of the giant Australian cuttlefish: comparing statoliths and cuttlebones

​Statoliths, Cuttlebone, Chemistry

​Mike Steer

Bronwyn Gillanders

  
KarinHüssy
In the Baltic Sea two genetically distinct cod stocks are found, the “Eastern Baltic cod” and “Western Baltic cod”. In this study we evaluated the applicability of otolith shape analysis for classification of individuals caught in the fishery within the presumed mixing area, using genetic validation of the otolith based assignments. The otoliths of eastern Baltic cod were generally wider in the dorso-ventral direction in relation to the anterior-posterior length than those of western Baltic cod. These differences were captured by otolith area and 7 – 10 Elliptic Fourier Descriptors of primarily low number harmonics. The genetic validation of otolith shape based classification of samples from the mixed-stock area revealed that the classification success using a baseline of spawning individuals was considerably lower than when a baseline of genotyped individuals including immature individuals also, was used. Stock mixing percentages using the latter documented that the “Eastern” cod stock has been present in the neighbouring management unit of the “Western” cod for many years. However, since 2005, their abundance has increased from 20% to >60% with a clear increasing age-related trend in presence. The observed immigration is not related to spawning migrations, as no seasonal effects on stock mixing were found.
DTU Aqua

​Jaegersborg Alle 1

​Charlottenlund

2920Denmark+45 35883458kh@aqua.dtu.dkTheme III: Population indicatorsPresentationThe Baltic cod: A case study for testing stock discrimination based on otolith shape analysis in a mixed stock fishery

​Baltic cod, stock mixing, otolith shape

Henrik Mosegaard

Jakob Hemmer-Hansen

Margit Eero

  
KarinHüssy
In the Baltic Sea two cod stocks are found, the “Eastern Baltic cod” and “Western Baltic cod”. One of the most persistent problems in relation to stock assessment of the Eastern cod stock is an acceptable level of precision in age estimation. Owing to the hydrographical regime in the Baltic Sea coupled with the migration dynamics of the cod, the otolith microstructure is characterised by low contrast between growth zones and irregular zone formation. Age estimation of the Western stock on the other hand is considered highly precise owing to the high contrast between growth zones. The objective of this study is to explore the applicability of otolith microchemistry patterns from the nucleus to the edge of the otolith for age validation. Otoliths of 4 year old individuals (agreed age reading from three independent readings) were selected and profiles of opacity and trace elements standardised to a common length. Patterns of opacity and trace elements from the Western stock were used to identify elements with signatures matching growth zones with respect to maxima and minima at the same distances from the nucleus. Eastern otoliths from were then examined for the occurrence of similar patterns in otolith trace elements. Matching patterns with respect to occurrence of minima and maxima in both otolith opacity and microchemistry of Western cod were found for Mg and Rb, Ba and Cu (to less extent Zn and Zr). No match was found for Pb, Sr, Mn, Na, Li. In Eastern cod however, only Mg and Rb showed a periodical pattern with maxima and minima at the same distances from the nucleus as the Western stock. We therefore propose that the incorporation of these two trace elements into the otolith may be linked to fish somatic growth and thus presents a tool for age validation in species where ageing is difficult.
DTU Aqua

​Jaegersborg Alle 1

Charlottenlund​

2920Denmark+45 35883458kh@aqua.dtu.dkTheme IV: Individual indicatorsPosterOtolith microchemistry: A useful tool for age validation?

​Age validation, microchemistry, Baltic cod

Franziska Heidemann

Hans-Harald Hinrichsen

Joachim Gröger

  
HélèneTABOURET
Tropical insular systems are colonized by diadromous organisms. Species belonging to Gobioidei, especially the Sicydiinae sub-family, are the largest contributors to the diversity of fish communities and have the highest level of endemism in these systems. Sicydiinae are amphidromous. Once hatching in freshwater, free embryos drift downstream towards the sea where larval development occurs. After a pelagic growth phase, post-larvae recruit back to rivers where they can colonize habitats far upstream. Recent studies suggest downstream movements of individuals living upstream. The evidence of such movements is essential for the management of the insular tropical hydrosystems that suffer from anthropogenic pressures, a loss of the ecological corridor and for the species conservation. However the reconstruction of the habitat use and fish movements, mainly based on the interpretation of the otolith elemental composition, must consider three assumptions: 1) habitats in which the fish can move have significantly different chemical composition, 2) signatures remain sufficiently stable over time and 3) the fingerprint record in the otolith reflects the geochemical signature of the water in which the fish resides. In this study, we investigated during one year the variability of the chemical composition waters of the St Etienne River basin in La Réunion Island (West Indian Ocean) with a monthly sampling throughout 12 sites. The elemental composition (Sr:Ca, Ba:Ca, B:Ca…) allowed a clear differentiation of the sampling sites. Considering these differences, we investigated the elemental composition of otolith of Sicyopterus lagocephalus (Teleostei:Gobioidei:Sicydiinae) from 9 sites in the same river basin in order to validate the use of elements as habitat markers. These markers were then used to reconstruct the habitat shifts of S. lagocephalus from the estuary to upstream habitats and try to clarify the hypothesis of a behaviour plasticity in this system.
Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, UMR CNRS-5252-IPREM, Université de Pau etdes Pays de l'Adour

​2 avenue Pierre Angot

​PAU

64053FRANCE+33(0) 5 59 40 77 56helene.tabouret@univ-pau.frTheme III: Population indicatorsPosterReading the environment before reading the otolith: a key to tell Sicyopterus lagocephalus stories in La Réunion Island rivers

Water chemistry

Freshwater goby

Behaviour plasticity

Insular hydrosystems



​Nils TEICHERT (ARDA, La Réunion)

Raphaël LAGARDE (ARDA, La Réunion)

Alexandre HOLUB (LCABIE, France)

Gaëlle BARBOTIN (LCABIE, France)

Henri GRONDIN (ARDA, La Réunion)

Christophe PECHEYRAN (LCABIE, France)

Gilles BAREILLE (LCABIE, France)

  
Audrey M.Darnaude
Otolith oxygen isotope ratios are increasingly used to discriminate marine stocks, and applied as a proxy for temperature in current and past oceans, assuming that variations in otolith d18O values reflect differences in temperature history. To investigate how closely otolith d18O values reflect the environmental experience of wild fish, we examined the otoliths and corresponding archival tagging dataset (>13,000 geolocations and in situ temperature records from ~200 free-ranging fish) gathered from a decade-long study of plaice spatial dynamics and population structure in the North Sea . By focusing on otoliths from fish with known annual migrations over three consecutive years and corresponding, location-inferred high-resolution model temperature and salinity data, we compared predicted and measured annual otolith d18O values for three offshore sub-stocks with discrete annual distributions and temperature or salinity ranges. For individuals recaptured after >6 months at liberty, we also compared monthly d18O values accreted in the otolith during tag recording time with concomitant d18O predictions based on the tag temperature records. Both predicted (from temperature and salinity data using the isotope fractionation equation for inorganic aragonite deposition) and measured annual d18O values demonstrated >96% correct sub-stock prediction. Measured and predicted annual d18O values however, although largely harmonious, did not fully match, even when inter-stock differences in seasonal otolith growth were taken into account. Moreover, small but consistent offsets were observed between individual high-resolution otolith d18O values measured during tag recording time and corresponding d18O predictions. Possibly resulting from variation in physiological response to temperature among stocks, these results provide a compelling indication of small yet consistent vital effects during oxygen fractionation between ambient water and the mature fish otoliths. A fuller understanding of the mechanisms underpinning otolith d18O signatures is therefore desirable in the interpretation of otolith d18O data for stock discrimination or temperature reconstruction.
CNRS (UMR 5119 ECOSYM)

Montpellier 2 University - cc 093

Montpellier

34095Franceaudrey.darnaude@univ-montp2.frTheme III: Population indicatorsPresentationUntangling inter-stock differences in otolith d18O signatures: insights from a decade of plaice archival tagging.
Anna Sturrock, Steven E. Campana, Clive N. Trueman, Ewan Hunter
  
BronwynGillanders
The world is seeing unprecedented changes in climate. Increased anthropogenic CO2 emissions associated with industrialization have resulted in an increase in atmospheric CO2 over the past two centuries. Associated with this atmospheric CO2 increase has been an increase in oceanic CO2 levels leading to a decrease in both pH and carbonate ion concentration, termed ocean acidification. Tracing either changes in pH through time or the pH history of fish throughout their life is difficult, but the ear bones (otoliths) of fish, which grow incrementally and accrete CaCO3 along with trace elements may provide a novel option. Our aim was to determine if trace elements in the otoliths of fish could be used as a natural tracer of variation in pH. We used two approaches to test this aim, a laboratory experiment and examination of field-caught fish that were collected from naturally elevated CO2 conditions. Our controlled laboratory experiment exposed fish to current and a future level of pH in combination with increased temperature. Benthic site-attached fish were also collected from two shallow water CO2 vent sites with collections being undertaken at varying levels of CO2. Trace elements in otoliths from both the laboratory and natural experiment were analysed using laser ablation inductively coupled plasma-mass spectrometry (LA ICP-MS). Relationships between CO2 and trace elements will be presented. This research helps to understand how changing environmental conditions are reflected in fish otoliths which has important implications for monitoring fish movement.
University of Adelaide

​Environment Institute & School of Earth and Environmental Sciences​, University of Adelaide

​Adelaide, South Australia

5005Australia61 417036235bronwyn.gillanders@adelaide.edu.auTheme I: Environmental indicatorsPresentationUsing fish ear bones as proxies for tracing changes in climate

​Otolith chemistry, climate change

Sean D. Connell, Zoe A. Doubleday, Jasmin Martino, Ivan Nagelkerken, Bayden D. Russell, Skye H. Woodcock

  
AoifeMcFadden
Elements such as Sr which are thought to be environmentally regulated, are of particular interest in the reconstruction of environmental conditions such as temperature histories. Recent studies of the shells of the bivalve Arctica islandica however revealed an association between the Sr/Ca, Ba/Ca and Mg/Ca ratios and crystal fabric. In particular, the heterogenous variation of Sr in the shells did not reflect environmental changes but rather showed an association to the crystal size and shape. Changes in Sr/Ca ratio, unrelated to environmental conditions, have been observed following a metamorphosis check in eel otoliths, similar to that observed in the annual growth checks in bivalve shells. These observations support the existence of a relationship between trace element concentrations (in particular Sr concentrations), and the microstructure of the otolith. In conjunction with microstructural interpretation, variation of the Sr/Ca ratio in otoliths of Platycephalus bassensis have been determined in an effort to uncover the role of biomineralisation in otolith trace element uptake. Microstructural analysis was undertaken by Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD), and subsequently Sr/Ca ratios across otolith growth increments were determined by Electron Probe Microanalysis (EPMA). Sr/Ca values were heterogeneously distributed across the otolith growth increments. SEM images and EBSD orientation data reveal the changes in otolith grain structure appear to be associated with the changing Sr/Ca values. The correlation between Sr/Ca ratio and grain size was indicative that Sr is not completely regulated by the environment, but is instead controlled by a complex interaction of biological and kinetic effects.
University of Adelaide

School of Chemistry and Physics; Adelaide Microscopy; School of Earth and Environmental Sciences, University of Adelaide & Department of Mineralogy, The South Australian Museum 

​Adelaide, South Australia

5005Australia61 417036235bronwyn.gillanders@adelaide.edu.auTheme I: Environmental indicatorsPosterOtolith Biomineralisation: Insights From a Microstructural and Microanalytical Study

​Otolith microstructure; otolith chemistry; scanning electron microscopy; electron backscatter diffraction; Sr:Ca

​Bronwyn M. Gillanders, Alan Pring, Benjamin Wade

  
GretchenGrammer
Otoliths (ear stones) from long-lived fish provide an indirect method to examine levels of radiocarbon (14C) resulting from nuclear weapons testing in the 1950s and 1960s (bomb radiocarbon, 14C), thereby allowing the changes in distribution of 14C in a region to be interpreted. Our research aims to examine the flux of the “bomb pulse” through the water column from surface waters to depths ≤ 1000 m in the south-western Pacific Ocean purely by using otolith radiocarbon. We examine 14C series from marine surface waters (Australasian snapper, Chrysophrys auratus; nannygai, Centroberyx affinis), 400 - 500 m (ocean perch, Helicolenus barathri) and 800 - 1000 m (orange roughy, Hoplostethus atlanticus), all collected from south-western Pacific areas. We compare 14C measurements micro-sampled from ocean perch otoliths to otolith surface water reference values and deep-water 14C values from orange roughy to establish for the first time a mid-water 14C series for depths of ~ 400 - 500 m through the years of 1947 - 2009. The linear trends of 14C during the greatest periods of increase for the three time series were correlated. For all series comparisons, the intercepts of increase differed, but the slopes were different only between the surface and deep-water series. These results indicate a 5 - 10 year lag between the surface and depths of 400 - 500 m and a 10 - 20 year lag between the surface and depths of 800 - 1000 m with depression of the slope of 14C increase as depth increases. Overall, application of fish otoliths to examine the bomb pulse of 14C provided valuable insights into the timing of 14C flux into depths approaching 1000 m in the south-western Pacific Ocean, an area deficient in instrumental temporal 14C records in waters below the mixed layer.
The University of Adelaide

Southern Seas Ecology Laboratories

School of Earth & Environmental Sciences

Darling Building DX 650 418

​Adelaide, SA

5005Australia+61 (0)8 8313 1483gretchen.grammer@adelaide.edu.auTheme I: Environmental indicatorsPresentationInvestigating the bomb radiocarbon flux in the southern Pacific Ocean with otolith radiocarbon

​bomb radiocarbon, otolith, radiocarbon flux, south-western Pacific Ocean, mid-water, Helicolenus

S. J. Fallon2, C. Izzo1, R. Wood2, B. M. Gillanders1

1Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, The University of Adelaide, SA 5005, AUSTRALIA

2Radiocarbon Facility, Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, AUSTRALIA

  
EudoxiaSchismenou
European anchovy (Engraulis encrasicolus) juveniles were collected from a coastal area in the North Aegean Sea in July 2007, December 2007 and February 2009. Otolith microstructure analysis revealed that anchovies had hatched from April to December. To reconstruct the potential environment that fish experienced during their development we used the output of a coupled 3D hydrodynamic-biogeochemical model (POM-ERSEM) implemented in the North Aegean Sea, which provided daily values of simulated environmental parameters averaged over the broader sampling area for the period January 2007-February 2009. According to the model simulation, fish caught in February grew in unfavourable conditions in terms of temperature, food availability and water stability; however, they were larger at age and more robust, exhibiting wider otolith increments for the period prior to metamorphosis and similar growth rate to fish caught in July. We hypothesized that these fish were fast-growers and survivors of a population that faced a severe size-/growth-selective mortality event. For further understanding of the environmental effects on anchovy daily growth rate we applied generalized additive model (GAM) analysis on the daily increment widths using the daily values of the simulated parameters as explanatory variables. In the model we also incorporated the effect of ‘inherent otolith growth’ by including the explanatory parameters ‘previous increment width’ and ‘age’. ‘Age’ along with ‘sampling period’ comprised an interaction term that accounted for seasonal variations in ontogenetic changes (timing and duration of metamorphosis) and differences in selective mortality among samples. Results indicated that the daily growth rate increased with increasing food availability (mesozooplankton biomass) and revealed an optimal temperature (~24.5 oC) for anchovy growth.
Hellenic Centre for Marine Research
Thalassokosmos
PO Box 2214
Former American Base, Gournes
Heraklion
71003Greeceschismenou@hcmr.grTheme IV: Individual indicatorsPresentationDisentangling the effects of inherent otolith growth and model-simulated ecosystem parameters on the daily growth rate of young anchovies

​European anchovy, otolith microstructure, northeastern Aegean Sea, coupled hydrodynamic-biogeochemical model, generalised additive model, eastern Mediterranean

Marianna Giannoulaki, Kostas Tsiaras, Eugenia Lefkaditou, George Triantafyllou, Stylianos Somarakis

  
SaraTurner
Early life habitat use and movements of successfully recruited adult fish can provide insight into critical nursery habitats. Retrospective analysis of adult otolith chemistry combined with fish-otolith growth models were used to assess nursery habitat selection and emigration size for anadromous alewife (Alosa pseudoharengus) and blueback herring (A. aestivalis) from 20 rivers in the eastern United States. Freshwater nursery use was observed approximately 8% more frequently in blueback herring than alewives, and use of combined freshwater and estuarine nurseries was observed approximately 9% more frequently in alewife than blueback herring. Estuarine nursery use was more common in southern rivers for both species. Emigration sizes were related to the latitude at the river mouth, watershed area, accessible river kilometers, and the percentage of the watershed in urban use. Principal component analysis was performed on the watershed variables; the first component, which encompassed 46.2% of the variation among rivers, explained 32.0% and 56.9% of the variation in mean emigration size among alewife and blueback herring populations, respectively.
SUNY College of Environmental Science and Forestry

1 Forestry Dr.​

Syracuse, NY

13210USA508-951-8115smturner483@gmail.comTheme III: Population indicatorsPosterJuvenile river herring habitat use and emigration trends throughout their U.S. ranges

​Otolith chemistry; Migration

Karin Limburg​

  
ZoeDoubleday
The analysis of annual growth increment patterns or ‘growth chronologies’ within the hard, calcified tissues of aquatic species, such as fish otoliths, can provide valuable information about how an individual grows throughout its lifetime and what key environmental variables influences that growth. We examine and compare broad and local scale drivers of the growth of black bream (Acanthopagrus butcheri), an economically important fish species found throughout temperate estuaries in southern Australia, using otolith growth chronologies. Sectioned otoliths were sourced from two pre-existing collections representing two climatically divergent regions in south-east Australia: the Lower Lakes-Coorong estuarine system in South Australia, characterised by a relatively warm, dry climate, and the east coast estuaries of Tasmania, characterised by a relatively cool, wet climate. Annual otolith growth increments were counted and measured in fish from 7 to 23 years old, encompassing the period from 1985 to 2010. Using a mixed modelling approach, we relate inter-annual growth variation to local scale changes in air temperature (proxy for water temperature) and rainfall (proxy for freshwater flows) and broad scale changes in relevant climatic indices (Multivariate ENSO Index and Southern Oscillation Index). Based on this analysis, we make predictions on how the growth of black bream, and thus the productivity of bream populations, may be impacted in the future based on climate change projections. This study further validates the use of growth chronologies, a new and emerging field of science, as a valuable tool for understanding long-term ecological responses to environmental change in aquatic systems.
The University of Adelaide
​School of Earth & Environmental Sciences
Darling Building DX 650 418 

​Adelaide, South Australia

5005Australia+61 8 83131485zoe.doubleday@adelaide.edu.auTheme III: Population indicatorsPresentationBroad and local scale drivers of growth of an estuarine fish species and implications for climate change

​otolith growth chronology, fish growth, estuary, south-east Australia, mixed modelling, climate change 

Chris Izzo, James Haddy, Jeremy Lyle, Bronwyn Gillanders

  
AndreasZitek
Until today 3D scanning of otoliths has been achieved with high-end instrumentation (Micro-CT) or only for otoliths larger than 1 cm in diameter e.g. by using a specialized projector and white light setup. So far, no affordable system for smaller otoliths (below 10 mm in diameter) exists, allowing for the archiving and accurate evaluation of otolith geometries.
Here, we present a new, comparably low-cost, system for 3D scanning of small otoliths (from 0.5 mm to 5 mm length), based on photogrammetry techniques. The hardware system consists of an USB microscope, an Arduino Uno Controller board, a stepping motor with a stepping motor driver and a self-designed and 3D printed stage. AgiSoft Photoscan is the underlying software system for the creation of the 3D model and works on the basis of merging sequentially recorded pictures. In total the system costs less than 600 U$. Once a 3D model of the otolith is established, the otolith model can be virtually cut along various planes yielding different 2D sections that can be then subjected to shape analysis. Compared to projector and white light based 3D scanning, the presented system is also able to capture the natural texture of the scanned otolith which provides additional information for interpretation. The method presented is expected to significantly improve the possibilities for differentiating and classifying fish from different sub-populations.
University of Natural Resources and Life Sciences Vienna, Department of Chemistry, Division of Analytical Chemistry, VIRIS Laboratory for Analytical Ecogeochemistry

​Konrad-Lorenz-Straße 24

Tulln, Lower Austria

​3430 Austria0043 676 780 65 15andreas.zitek@boku.ac.atTheme III: Population indicatorsPosterAffordable 3D scanning of small otoliths for improved shape analysis by photogrammetry techniques

Fish otoliths, Image based 3D scanning, Shape analysis, Origin of fish, Discrimination of fish species

Bernhard Mayrhofer, Johannes Oehm, Johanna Irrgeher, Thomas Prohaska

  
AndreasZitek
Transgenerational isotopic marking has been recognized as an efficient tool for mass marking of high numbers of fish larvae by injecting female spawners with enriched isotope solutions. So far mainly enriched stable barium isotopes have been applied for this purpose. Here, we present an alternative approach for transgenerational marking using natural stable strontium (Sr) isotope spikes as non toxic alternative administered at natural Sr levels. The successful transfer of enriched stable Sr isotope single and double spikes (84Sr and 86Sr/84Sr) from female spawners of brown trout (Salmo trutta f.f. ) and common carp (Cyprinus carpio L.) to the centre of the otoliths of their offspring was studied by (laser ablation) multi collector inductively coupled plasma mass spectrometry ((LA)-MC ICP-MS). In the case of the 86Sr/84Sr double spike experiments, isotope pattern deconvolution (IPD) (applied to LA-MC ICP-MS data) allowed for the re-identification of unambiguous individual-specific Sr isotope signatures in the otolith cores of the offspring. Enriched stable Sr isotope double spikes show great potential for transgenerational marking especially in freshwater systems, since absolute tracer doses needed to induce a significant mark in the otolith can be kept low and the use of a double spike allows for the variation of the composition resulting in a large number of individual distinguishable fingerprints. Details on the metrological protocol for data processing during isotope pattern deconvolution (IPD) are given in the presentation of Johanna Irrgeher et al., Sr isotope pattern deconvolution of LA-MC ICP-MS data to detect individual-specific transgenerational marks in freshwater fish otoliths.
University of Natural Resources and Life Sciences Vienna, Department of Chemistry, Division of Analytical Chemistry, VIRIS Laboratory for Analytical Ecogeochemistry

Konrad-Lorenz-Straße 24

Tulln, Lower Austria

3430Austria0043 676 780 65 15andreas.zitek@boku.ac.atTheme III: Population indicatorsPresentationTransgenerational marking of freshwater fish otoliths using enriched stable Sr isotopes

​Strontium, Enriched isotope double spikes, Freshwater, Fish otoliths, LA-MC ICP-MS

​Johanna Irrgeher, Thomas Prohaska

  
KéligMAHE(1)
Swordfish (Xiphias gladius) is an oceanic-pelagic species currently fully exploited by several fisheries in the Indian Ocean, with suspicion of overexploitation in the southwest, but without a clear understanding of the real stock structure within this Ocean. Population structure of the Indian stock was studied in the western Indian Ocean using 395 individual samples collected from 2009 to 2014. Sagittal otoliths of the fish have been removed and shape analysis performed on these calcified pieces. Otolith morphometrics data and normalized Elliptical Fourier Descriptors (EFDs) were then extracted automatically by the dedicated image-analysis system TNPC. Preliminary, side effect was tested by Redundancy analysis (RDA) combined to permutation tests on 91 individual samples and showed no significant differences in the outline shape between the right and left otoliths. Consequently, 395 sagittal otoliths were used to identify stocks among several geographical areas (La Reunion, Mozambique channel, Rodrigues, South Africa, South Malagasy, Sri Lanka and Thailand) within the Indian Ocean. To investigate variations of otolith shape according to 4 explanatory variables, Principal Components Analysis (PCA) was applied to EFDs and a RDA with permutation tests was used on the first 7 PC selected by the broken-stick model. These tests demonstrated no significant effects, neither by geographical area (p=0.203), sampled year (p=0.505), or total length (p=0.092). Only, fish sex appeared to be significant (p=0.026). Regarding the relationship between the ratio otolith length/otolith width and the total length of fish, size effect was neither significant. Furthermore, Linear Discriminant Analysis (LDA) was performed and overall jackknifed classification success reached 30%. Finally, a clustering analyse has been realised using Ward's hierarchical algorithm, which discriminated 3 different groups, however each group was composed by some individual samples from all geographical areas. In conclusion, all these results did not show a clear geographical separation, and this conclusion corroborate the recent genetic analyse at the Indian Ocean scale while identifying only a single swordfish stock component in the Indian Ocean.
1 : Ifremer, laboratoire Ressources Halieutiques 2 : Ifremer, Délégation Océan Indien

​150 quai Gambetta

​Boulogne sur mer

62321France+0033 3 21 99 56 02 kelig.mahe@ifremer.frWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPresentationThe use of otolith shape to evaluate the stock structure of swordfish (Xiphias gladius) in the Indian Ocean

​Xiphias gladius, otolith shape, Fourier descriptors, stock discrimination, Indian Ocean

​Hugues EVANO(2), Tiphaine MILLE(1), Jérôme BOURJEA(2)

  
JohannaIrrgeher
Spiking of fish or water with enriched stable (natural) isotopes has developed into an important tool in fish ecology. In order to apply minimum, non-toxic levels of spike, adequate methods for data reduction needed to be developed in order to identify the spike and properly calculate the original spike composition. This comes of special importance if different isotopic compositions of the spike are applied in order to uniquely identify different entities (e.g. differently marked fish of the same species). In order to meet these prerequisites, a full metrological protocol for data processing during isotope pattern deconvolution (IPD) of an enriched Sr isotope double spike as intrinsic marker in a biological system is described for the first time. The method was developed based on data gained during two transgenerational marking studies of fish, where the transfer of a Sr isotope double spike (84Sr and 86Sr) from female spawners of common carp (Cyprinus carpio L.) and brown trout (Salmo trutta f.f. L.) to the centre of the otoliths of their offspring was studied by (laser ablation) multi collector inductively coupled plasma mass spectrometry ((LA)-MC ICP-MS). Isotope pattern deconvolution, based on multiple linear regression, serves as simplified alternative data processing strategy to double spike isotope dilution calculations. The outstanding advantage of this mathematical tool lies in the possibility of deconvolving the isotope pattern in a spiked sample without knowing the quantities of enriched isotope tracer being incorporated into the natural sample matrix as well as the degree of impurities and species-interconversion (e.g. from sample preparation). Therefore, all applied spikes could be identified even at concentrations down to 10 µg kg-1 fish. Biological details of this study are given in the presentation by Zitek et al., Transgenerational marking of freshwater fish otoliths using enriched stable Sr isotopes.
University of Natural Resources and Life Sciences Vienna, Department of Chemistry, Division of Analytical Chemistry, VIRIS Laboratory for Analytical Ecogeochemistry

​Konrad-Lorenz-Straße 24 

Tulln

3430 Austria​​00436507383068johanna.irrgeher@boku.ac.atTheme III: Population indicatorsPresentationSr isotope pattern deconvolution of LA-MC ICP-MS data to detect individual-specific transgenerational marks in freshwater fish otoliths

​Strontium, Enriched isotope spikes, Isotope pattern deconvolution, Fish otoliths, LA-MC ICP-MS

​Andreas Zitek

Thomas Prohaska

  
Mohammad Afzal Khan
The giant river catfish, Sperata seenghala, is one of the most important bagrid catfish captured in Indian subcontinent. The wild population of the fish has shown declining trend over the years but there is paucity of published information on its population structure. However, a comprehensive knowledge on the stock structure is necessary for proper management and conservation of the target fish species. Therefore, the present study was undertaken with a view to discriminate the stock(s) of Sperata seenghala population collected from Narora, Kanpur and Bhagalpur sites on the Ganga River, Firozabad site on the Yamuna River and Lucknow site on the Gomti River using elemental fingerprints on otoliths. Fifteen trace elements from whole sagittal otoliths were analysed using inductively coupled plasma atomic emission spectrometry. For each site, elemental concentrations were subjected to appropriate uni- and multivariate statistical tests. Strontium, barium, lithium, copper, iron, lead, zinc, manganese, nickel (p0.01). Chromium and cadmium were not detected in the otoliths of the fish from Narora site on the river Ganga. Discriminant function analysis using cross-validation classification, assigned individuals to their site of sampling origin with a mean classification accuracy of 83.2%. The detected site-specific elemental differences in S. seenghala otoliths indicate a high level of site-fidelity in relation to their habitat areas. The target fish population from these sites can be regarded as heterogeneous stocks forming separate units for fisheries management in the selected rivers.
Aligarh Muslim University, Aligarh – 202 002, India

1Section of Fishery Science and Aquaculture, Department of Zoology, Aligarh Muslim University, Aligarh– 202 002, India

*Corresponding Author: E-mail: khanmafzal@yahoo.com; Mobile No.: +91-9457007109

2Indian Institute of Toxicology Research (Council of Scientific and Industrial Research), Lucknow-226 001, India

​Uttar Pradesh

202 002India+91-9457007109khanmafzal@yahoo.comTheme III: Population indicatorsPresentationDiscrimination of Sperata seenghala stocks inhabiting three rivers of the Gangetic river system using elemental fingerprints on otoliths

​Key words: Sperata seenghala, stock discrimination, otoliths fingerprints, Ganga River, Yamuna River, Gomti River

​Kaish Miyan1, Devendra Kumar Patel2, Shahista Khan1 and Satgur Prasad2

  
YvetteHeimbrand
In the Baltic Sea two major reproductive forms of whitefish (Coregonus maraena) are recognized; a migratory form spawning in coastal rivers and a more resident form spawning in shallow bays. Although these ecological forms differ somewhat morphologically there is a large overlap in characters and no clear-cut way to differentiate between them. The drastic decline of whitefish in the northern Baltic Sea in recent years highlights the need to differentiate between spawning types in order to make reliable assessment and take effective management actions. By using the chemical composition of otolihts as indicator of the environment the life history of a fish can be revealed. Otoliths are skeletal structures of the inner ear that grow during the life of the fish while incorporating elements from the surrounding water. Since the ratio of Strontium and Calcium are related to the salinity of the water the Sr/Ca ratio in the otolith could be used to distinguish between marine and freshwater origin of the fish. In an experiment, otoliths were prepared from 7 adult whitefish from the river Gideälven, and 12 adults from the Söderhamn archipelago. PIXE analysis of polished otoilths mounted on an object glass revealed that despite sampling during spawning time in supposedly different spawning habitats there was a mix of fish that originated from river spawners and sea spawners in both areas. Only 2 of the 7 fish from Gideälven had spent their first year in freshwater while 3 of the 12 fish caught in the archipelago had a freshwater origin.
Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Coastal Research

Skolgatan 6​

Oregrund​

SE-74242Sweden+46 76 8281147yvette.heimbrand@slu.seTheme I: Environmental indicatorsPosterUsing otoliths to distinguish sea spawning from river spawning whitefish (Coregonus mareana).

Otolith chemistry​; Whitefish; Salinity

Odelström, A.  Elfman, M. Florin, A.-B.

  
AnneOdelstrom
Three-spined stickleback is a species that has received considerable attention in behavioural ecology, while relatively little is known about its life cycle and role in the food web, especially in marine and estuarine systems. Available data suggests that sticklebacks have increased dramatically in abundance since the early 2000's in different parts of the Baltic Sea, and the species now constitutes a considerable part of the fish biomass of both offshore and coastal ecosystems. Sticklebacks have been shown to affect the dynamics of coastal ecosystems, by affecting biomasses of large predatory fish like pike and perch, as well as the production of ephemeral algae. Despite this, little is known on the life-history of sticklebacks in the Baltic Sea. In order to increase the knowledge base, we have made an attempt to age three-spined sticklebacks on the spawning grounds in coastal shallow bays and in offshore areas of the Baltic Sea.
A total of 155 individuals from the northern and central parts of the Baltic Sea were analyzed, and individual lengths were determined to the nearest millimetre. Grounded and polished otoliths were examined using a stereo microscope to determine the number of annual rings. Determining the position of the first annual ring was difficult due to “false” rings. To aid correct age determination, a method was developed where the first annual ring was identified by staining and counting of daily growth increments.
A high temporal variation in age and length was shown among sticklebacks caught at the coastal site, depending strongly on spawning season. In the offshore the length at age differed slightly between areas. Individuals from the northern part of the Baltic Sea were significantly larger, at the same age, compared to the fish from central part. The oldest individuals found in the northern area were 4 years and in the central area 3 years, some reaching a total length over 9 cm.
Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Coastal Research

Skolgatan 6​

Oregrund​

SE-74242Sweden+46 104784143anne.odelstrom@slu.seWorkshop on age validationPosterLife-history/age structure of three-spined sticklebacks in the Baltic Sea.

Three-spined stickleback; Age determination; Otolith

Anne Odelstrom, Carin Angstrom, Ulf Bergstrom, Jens Olsson​

  
YohYamashita
The temperate seabass Lateolabrax japonicus is a euryhaline species found along northeastern Asian coasts. Landings of this species from Japanese coastal waters have been increasing over the past 25 years. Juveniles utilise various coastal habitats as nurseries, such as eelgrass beds, sandy beaches, tidal flats and estuaries. The importance of estuaries as nursery areas for temperate seabass has been emphasised by several recent studies. To assess the values of estuarine nursery grounds, the contribution of estuarine areas to the production of temperate seabass populations was estimated using otolith Sr:Ca ratios in Tango Bay, Sea of Japan. Otolith Sr:Ca ratios of juveniles collected from freshwater and brackish areas of the Yura River estuary, which flows into Tango Bay and coastal areas were analysed to determine a criterion for distinguishing whether individuals used estuarine or coastal areas as nurseries. The mean value of Sr:Ca ratios at the edges of otoliths of juveniles showed significant differences between areas (P < 0.01), measuring 4.9 × 10–3, 4.0 × 10–3 and 2.4 × 10–3 in the coastal, estuarine and freshwater areas, respectively. The mean minus standard deviation of the Sr:Ca ratio of individuals from the coastal area was 4.4 × 10–3 and this value was used to estimate the nursery type utilised by juveniles. Otolith Sr:Ca ratios of adult seabass collected around Tango Bay were also analysed. Thirty-nine of 107 (36 %) adult seabass were estimated to have used the estuary as a nursery during their juvenile stage according to their Sr:Ca chronologies. Despite the small area covered by estuarine nurseries compared with coastal waters, the estuary contributed considerably to the adult seabass population. This indicates the estuary plays an important role as a nursery area for seabass juveniles.
Field Science Education and Research Center, Kyoto University

​Kitashirakawa-Oiwakecho, Sakyoku

​Kyoto

606-8502JAPAN+81-75-753-6410yoh@kais.kyoto-u.ac.jpTheme I: Environmental indicatorsPresentationRelative contribution of estuarine nursery areas to the adult population of the temperate seabass Lateolabrax japonicus in Tango Bay, as revealed by otolith Sr:Ca ratios

seabass, Sr:Ca ratio, estuary, nursery ground, juvenile

Taiki FUJI, Akihide KASAI, Masahiro UENO, Yoh YAMASHITA

* Presenter is Yoh Yamashita

  
MartinaBlass
In general, age determination of Bothnian sea herring is based on microscopic inspection of sectioned otolith. This method is quite expensive but considered to give reliable results. An alternate and cheaper method was tested using grinded transversal and stained otoliths.
A test was set up in order to compare the two methods in terms of potential bias. The hypothesis was that the alternative method will underestimate number of growth zones of northern herring compared to the traditional method.
For the study a total of 90 herrings consisting of four samples from the the Bothnian Sea and two from the Bothnian Bay were prepared and read. The herring was selected from samples by hydroacoustic research surveys and commercial fisheries collected in spring and autumn 2013. From each individual one otolith (sagitta) was sectioned by a diamond saw and stained with neutral red. The other otolith was mounted on a polycarbonate chip with the centre of the nucleus at the edge of the chip and then grinded, polished and stained.  This enabled a pairwise comparison of age determination methods.
Results showed that all readers estimated higher age from sectioned otoliths than from grinded. The difference was 1-2 years in mean age for the whole sample. For sectioned otoliths, variance of the age estimate was higher than for grinded samples. Variances did not, however differ significantly. For both methods, variance increased with age (median for both methods).
Between pairs of readers, the mean difference between age estimates was between 0,2-0,9 years for sectioned otoliths and between 0,1-1,1 for grinded otoliths. Age estimates from sectioned otoliths did not differ significantly for any pair of readers.  Estimates from ground otoliths differed significantly for three pairs of readers.
Sectioned otoliths seem more reliable, and microscope magnification may explain much of the difference.
Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Coastal Research

Skolgatan 6​

Oregrund​

SE-74242Sweden+46 104784118martina.blass@slu.seWorkshop on age validationPosterComparing two methods of age determination of herring (Clupea harengus) in the Bothnian Sea and the Bothnian Bay.

Age determination, Clupea harengus, Bothnian Sea, Bothnian Bay​

Martina Blass1 Jan Eklund2, Mikael Elfving2, Yvette Heimbrand1, Carina Jernberg1, Marju Kaljuste1, Anne Odelstrom1

1Department of Aquatic Resources, Swedish University of Agricultural Sciences, 2Archipelago Research Institute
University of Turku​

  
SanjaMatić-Skoko
There is a need to establish a method for age determination of the striped red mullet, Mullus surmuletus as target fish species of Mediterranean artisanal fisheries. In total, 387 specimens ranging in total length from 6.8 to 32.9 cm were analyzed for this purpose. Ground otoliths were used to estimate fish ages. The annual periodicity of annulus deposition was supported by the marginal increment analysis. The annual growth of otoliths was verified using edge-type analysis. The formation of growth increments followed a seasonal pattern. The proportion of otoliths with opaque margins was the highest (>80%) in the winter period (December-March). Moreover, the monthly mean marginal increment showed a single minimum in June and confirmed the formation of one annulus per year. A distance measurements analysis revealed that first regular ring appears at distance of 0.78 mm (± 0.104 SD) from otolith nucleus and fish age of about 0.83 years. The age analysis revealed 6 age classes. Predominance of age classes 1+ and 2+ in the total catch (54.3% individuals) was observed. All measured otolith morphometric parameters (length, width and mass) were linear with fish age. The linear model explained between 80.3% and 84.4% of the variation in age. The most precise age estimations of analyzed population were obtained from the otolith width, followed by the otolith length and mass. The growth parameters were estimated by the fit of the Von Bertalanffy growth function. The growth of M. surmuletus was rapid up to 2 years of age and then slowed. Considering the identified biological implications, existing management should be complemented by a more holistic, ecosystem approach to regulations, in order to assure effective conservation measures for this economically and ecologically important fish species.
Institute of Oceanography and Fisheries

​Mestrovicevo setaliste 63

​Split

21000Croatia+385 21 408 030sanja@izor.hrTheme III: Population indicatorsPosterAge determination and validation on otoliths of the striped red mullet, Mullus surmuletus from the Adriatic Sea

age, otolith, Mullus surmuletus, Adriatic Sea

Sanja Matić-Skoko*1, Josipa Ferri2, Dajana Brajčić Jurica3

 

1Institute of Oceanography and Fisheries, Šetalište Ivana Meštrovića 63, P.O. Box. 500, 21000 Split, Croatia

2University of Split, Center of Marine Studies, Livanjska 5/III 21000 Split, Croatia

3Fishermen Cooperative Fresh Fish, 21000 Split, Mažuranićevo šetalište 24b, 21000 Split, Croatia

*Corresponding author: sanja@izor.hr (S. Matić-Skoko)

  
CharlotteSirot
In order to better understand the causes for inter-specific difference in fish population responses to 30 years of environmental changes in a vast tropical lagoon (the lagoon of Terminos, Mexico), past and recent growth patterns were compared between two species showing opposite demographic trends in the area: the Silver Perch Bairdiella chrysoura (Scianidae) experienced a strong decline in abundance while the Western Atlantic seabream Archosargus rhomboidalis (Sparidae) kept its population constant. About 400 otoliths, from adults and juveniles of the two species caught at three distinct time periods (1980, 1997, and 2006-2011), were used to characterize inter-specific differences in growth patterns and their temporal modifications. After validation of the time for opaque marks deposit in the study area, seasonal growth increments were used to estimate individual age (in months) for both species. These data were then used to model population growth curves and average lifetime growth patterns for each species and period. Our result showed that both species shared similar growth patterns with no significant change since the 80's. However, temporal comparisons of lifetime growth profiles revealed that, contrary to A. rhomboidalis, B. chrysoura suffered a non-negligible decrease (-15%) of its average growth rate during early juvenile life (i.e. during the first four months following settlement in the lagoon) over this period. This modification helps elucidating why B. chrysoura experienced a severe population decline in the lagoon since 1980, while in the meantime A. rhomboidalis proved resistant to environmental perturbations.
5119 ECOSYM Ecologie des systèmes marins côtiers, Université Montpellier 2

CC 093, place E. Bataillon, 34095 Montpellier Cedex 05, France.

​Montpellier

34095France+33 6 50 22 54 90charlotte.sirot@univ-montp2.frTheme IV: Individual indicatorsPosterPast and recent growth patterns in two species with contrasting demographic responses to environmental changes in a tropical lagoon

​Growth, tropical lagoon, environmental modifications, species demographic change

Audrey DARNAUDE1, Julia RAMOS-MIRANDA2, Domingo FLORES-HERANDEZ2 & Jacques PANFILI1

1UMR 5119 ECOSYM Ecologie des systèmes marins côtiers, Université Montpellier 2, CC 093, place E. Bataillon, 34095 Montpellier Cedex 05, France.

2 Centro de Ecologia, Pesqueria y Oceanografia de Golfo de Mexico (EPOMEX), Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Campeche, Mexico 24030.


  
MaiduSilm
The eel population in the Narva River basin is based entirely on stocking. Prior to year 2001 eels were stocked into lake Võrtsjärv (270 km2) mostly in glass eel stage while from 2001 to 2010 only as elvers. From year 2002 young farmed eels were introduced to smaller lakes such as Lake Kaiavere, Lake Vagula, Lake Saadjärv and after the year 2003 Lake Kuremaa. More than 900 eel otoliths were gathered from 1999 to 2012 and treated with „burning and cracking“ method. In Lake Võrtsjärv the average annual growth rate of the eel stocked in glass eel stage was faster by 0,6 cm a year compared to the eels released as elvers, although the latter were 8 cm longer at the time of release. General growth rate was very good – 6,7 cm per year, beeing higher than indicated by previous results obtained in 1998 (5,9 cm). In four smaller waterbodies it was found that most likely the age of eel was overestimated due to the deposition of supernumerary zones in a rapid growth periood, being slower from Lake Võrtsjärv by 3,4 cm per year (P
Estonian University of Life Scienses

​Kreutzwaldi 1a

Tartu, Tartumaa
51014Estonia+37253765139maidu.silm@emu.eeWorkshop on age validationPosterEstimating the age and growth of European eel (Anguilla anguilla) in Estonian lakes using „buring and cracking“ method on otoliths.

​Burning and cracking; age; eel; anguilla anguilla; otolith; Estonia; 

​Ain Järvalt; Priit Bernotas; Aile Mäe

  
CharlotteSirot
Otoliths provide the opportunity to better understand the biological and ecological mechanisms responsible for fish demographic changes in disturbed environments by allowing investigation of temporal changes in life history traits. Recent findings suggest that they contain reliable information on individual trophic position available through analysis of the isotopic composition (δ13C and δ15N) of their organic matrix. These recent methodological developments were used here to study mid-term modifications in both trophic niche and growth for an exploited sciaenid (Bairdiella chrysoura) population undergoing an abundance decline in the Terminos lagoon (Mexico) through the last 30 years. Modifications of the species' trophic niche were evaluated by comparing the recent (2011) and past (1980) otolith protein signatures in δ13C and δ15N of 62 adults. Changes in growth were investigated by comparing the length-at-age relationships modeled for the two periods using otolith growth mark interpretation, but also through the assessment of body condition and lifetime growth rate. Our results showed that although the abundance of B. chrysoura in the lagoon has decreased of 60% since 1980, neither population growth pattern nor diet experienced major modification over the studied time period: growth models did not statistically differ and trophic niches largely overlapped. However, early juvenile growth in the lagoon has decreased since 1980, and average body condition is now higher at the adult stage. Moreover, otolith isotopic signatures also indicated a slight expansion of the population’s trophic niche since 1980, concomitant with an increase of δ13C and a decrease of δ15N. The possible links between these observations and their ecological implications on B. chrysoura population are discussed in relation with the environmental changes that occurred in the lagoon since 30 years.
UMR 5119 ECOSYM Ecologie des systèmes marins côtiers, Université Montpellier 2

Université Montpellier 2, CC 093, place E. Bataillon, 34095 Montpellier Cedex 05, France.

​Montpellier

34095France+33 6 50 22 54 90charlotte.sirot@univ-montp2.frTheme IV: Individual indicatorsPresentationUsing otoliths to link population abundance decline to modifications in individual trophic niche and growth in a tropical fish species (Bairdiella chrysoura L., Sciaenidae)

stable isotope signature, trophic level, growth, tropical lagoon, species decline, environmental modifications

Peter GRØNKJÆR2, Jens BRØGGER PEDERSEN2, Manuel ZETINA-REJON4, Arturo TRIPP-VALDEZ4, Julia RAMOS-MIRANDA3, Domingo FLORES-HERANDEZ3, Jacques PANFILI1 & Audrey DARNAUDE1

1UMR 5119 ECOSYM Ecologie des systèmes marins côtiers, Université Montpellier 2, CC 093, place E. Bataillon, 34095 Montpellier Cedex 05, France.

2Marine Ecology, Department of Biological Sciences, Building 1135, Ole Worms allé 1, Aarhus University, 8000 Åarhus C, Denmark.

3Centro de Ecologia, Pesqueria y Oceanografia de Golfo de Mexico (EPOMEX), Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Campeche, Mexico 24030.

4Centro Interdisciplinario de Ciencias Marinas (CICIMAR-IPN), Av. Instituto Politécnico Nacional S/N, Col. Playa Palo Sta. Rita, La Paz, Baja California Sur 23096, Mexico



  
ElenaBarcala
The illicium (first dorsal fin ray) has become the standard structure for age estimation of black anglerfish (Lophius budegassa) in most of the European countries and the one used as a basis for stock assessment, after calibration exchanges among the age readers and workshops. However, the tendency in the past to not pay essential attention to the need to validate or corroborate the age estimation in some stocks has led to misunderstanding of their dynamics. Thus, the Atlantic black anglerfish stocks have not been annually assessed using age-structured models during the last years in ICES working groups due to problems with the data quality, including those coming from a biased illicia age estimation criterion. The same age estimation criterion is used for the Mediterranean black anglerfish. Evidence obtained in the last years, using alternative methodologies to the age estimation, have shown a faster growth rate of black anglerfish. Some growth increments considered as annuli in illicia do not seem to be really annual.
The growth pattern of black anglerfish in Spanish Mediterranean waters is analyzed in this study using the length-frequencies (lengths ranging 3-128 cm) of annual groundfish research surveys between 2004 and 2012. The results corroborate that the growth pattern of the Mediterranean population of this species is also faster than that estimated applying the traditional illicia age estimation criterion. The von Bertalanffy growth parameters are also estimated and compared to those of previous studies; they will be available if a length-structured model including growth parameters is used in the assessment of this Mediterranean stock.
Spanish Institute of Oceanography

C/Varadero s/n​

San Pedro del Pinatar, Murcia​

30740Spain+34 968 179412elena.barcala@mu.ieo.esWorkshop on age validationPosterCorroboration of faster annual growth rate of black anglerfish (Lophius budegassa) in Spanish Mediterranean based on length frequency analysis.

Black anglerfish; Monkfish; Lophius budegassa; Growth; Length-frequency; Mediterranean; Groundfish surveys. ​

Jorge Landa​

  
EdouardLavergne
Early life history of Terapon jarbua (Forsskål, 1775) was examined using otolith microstructures, otolith elemental composition and assignment test and was linked with previous analysis of microsatellite genotypes. Eight estuaries from Socotra Island and mainland Yemen were sampled in 2007 and 2008. Laser ablation inductively coupled mass spectrometry transects across otolith growth axes of juvenile T. jarbua were used to estimate early life migration of the species. Sr:Ba ratios across each transect were particularly sensitive to transitional environments, such as estuaries. Terapon jarbua exhibited a natal marine phase, migrating after a relatively short planktonic larval stage into estuarine systems as post larvae or young juveniles in which they remained for at least two years. An average planktonic larval duration of 25.1 days was estimated and remained stable over the studied region. The study highlighted that elemental fingerprints of otolith edges have great potential for discriminating nursery areas at both small (< 10 km) and large geographical scales (80 % assignment accuracy). This tool might be useful to estimate the contribution of specific estuarine nurseries to any adult stocks and should be used in the future to build pertinent management and conservation programs devoted to the Socotra estuaries. However, temporal variability in otolith elemental composition has been observed, thus making its routine usage more demanding. Elemental fingerprints of the otolith nuclei had meanwhile a lower potential for discriminating unknown marine spawning grounds but pointed out the existence of several different spawning areas, thus supporting previous results on population structure and population dynamics of T. jarbua.
Kyoto University, Field Science Education and Research Center (FSERC), Educational Unit for Studies on Connectivity of Hills, Humans and Oceans (CoHHO)

​Oiwake-cho, Kitashirakawa, Sakyo-ku

​Kyoto

606-8502 Japan+81 75-753-6425edouard.lavergne@gmail.comTheme III: Population indicatorsPresentationEarly life history of Terapon jarbua (Forsskål, 1775) using microstructures and Laser Ablation ICP-MS elemental composition of otoliths

​Otolith, nursery, fingerprint, connectivity, Socotra Island, Gulf of Aden, Yemen

Lucie Sellin, Maylis Labonne and Jean Laroche

  
Jan-OlofLill
European whitefish (Coregonus lavaretus) exists in two sympatric forms in the northern Baltic Sea; an anadromous river spawning and a sea spawning form. The groups form mixed populations outside breeding time and place. The river spawning whitefish in the northern Baltic Sea has diminished mainly due to anthropogenic destruction of the spawning rivers and the conditions in them, and is presently listed among endangered species on the HELCOM red list of Baltic Sea species in danger of becoming extinct (BSEP 140) and as a globally vulnerable species on the IUCN red list of threatened species. Methods for whitefish identification are a prerequisite for a sustainable management of the fish stocks. However, river spawning whitefish cannot be distinguished from sea spawning whitefish based on outer morphology, and alternative methods are therefore searched for. In this work we describe an application of particle-induced X-ray emission (PIXE) to the elemental analysis of polished otoliths of whitefish. Two spot on polished otoliths were irradiated; one spot in the centre of the otolith and one in the periphery. The irradiations were performed in air with a collimated 0.5 mm proton beam. The ratio of the strontium concentrations in the two spots was used to distinguish between the different groups of whitefish. Criteria on the ratios were suggested for identification of the whitefish groups. The results were compared to results of µ-beam PIXE scans as well as multi-point scans with the 0.5 mm proton beam. The measuring set-up and the results are discussed.
Accelerator Laboratory, Turku PET Centre, Åbo Akademi University

​Porthansgatan 3

​Turku

FI-20500Finlandjlill@abo.fiTheme IV: Individual indicatorsPosterTwo-spot PIXE analyses of polished otoliths for identification of anadromous whitefish in the Baltic Sea

Otolith, strontium, whitefish, Baltic Sea, PIXE

Mikael Himberg, Joakim Slotte, Yvette Heimbrand, Ann-Britt Florin, and Henry Hägerstrand

  
StefanoMontanini
Gurnards are demersal fishes exploited by commercial trawl fisheries that spend a pelagic phase during their early life history stages. There are eight different species in the Mediterranean showing intra- and inter-specific differences related to feeding habits, depth distribution and biological cycle. Although these changes have been widely reported little is know about their first life stages due to a lack of information on age and size at settlement to the bottom, length at first year of age and otolith formation. The present study is the first attempt to determine the first growth stages of six gurnard species: Chelidonichthys cuculus, C. lucerna, Eutrigla gurnardus, Lepidotrigla cavillone, L. dieuzeidei and Trigloporus lastoviza and to determine the first annuli formation. Indirect validation is made by counting presumed daily increments on two defined radii: the first radius is measured along the proximal-distal axis from the primordium to the last increment before the apparition of an accessory growth centre (AGC); the second radius is measured from the more dorsal AGC to the proximal edge of the otolith close to the sulcus acusticus and perpendicular to the increment deposition. The duration of the pelagic life phase was determined and the first annulus was defined by the position of one year-increment count in terms of distance from primordium and annulus density (i.e., translucent vs. opaque). The location of discontinuous and incremental zones linked to developmental changes, the description of the species-specific patterns, as well as the measurement of increment widths are discussed in the light of the species ecology and biology.
University of Bologna

​via Selmi 3

​Bologna

40126Italy0039-0512094166stefano.montanini2@unibo.itWorkshop on age validationPosterValidation of first annulus formation in Triglidae family (Teleostei, Scorpaeniformes):  a tool for increase the biological knowledge of a demersal resource

​gurnards, Mediterranean, otolith daily increments, first-year growth

​Maria Vallisneri, Silvia Pérez-Mayol, Miquel Palmer, Beatriz Morales-Nin

  
CindyTribuzio
The methods for ageing sharks (and all chondrichthyan fish) are often different from those used for teleost fish species. Sharks do not have highly calcified otoliths and in some cases, the cartilage does not calcify enough to make annuli discernible in other hard parts. This is the case for spiny dogfish (Squalus suckleyi), in which historical research deemed the vertebrae unusable; thus the dorsal fin spine ageing method was developed in the 1930s and has not changed since. Dorsal fin spine ages have been validated by both oxytetracycline tag and release studies and bomb radiocarbon. Despite the prevalence of using the dorsal fin spine ageing method, there are known caveats associated with this approach. The dorsal fin spines protrude into the environment and are often broken or worn, especially in larger, older animals, necessitating an analytic method to account for lost annuli. Dorsal fin spine ages are highly uncertain due to the difficulty in reading these structures, resulting in high inter- and intra-reader variation, and the analytic method accounting for lost annuli adds another source of uncertainty to the age estimates. This study examines a new method for ageing spiny dogfish which uses histological staining techniques on vertebrae thin sections. Spine and vertebra ages generated by multiple readers were compared to estimate inter-reader precision and the variance associated with each structure. Results suggest that ages derived from the vertebrae thin sections are similar to those derived from the dorsal fin spines; however the vertebra between-reader variability is reduced and there is no need to account for lost annuli. Results presented here are part of a larger study; these data will be used to generate improved growth models with reduced uncertainty in the growth parameters, which will be used in stock assessments.
National Marine Fisheries Service

17109 Pt Lena Loop Road​

​Juneau, AK

99801United States9077896007cindy.tribuzio@noaa.govTheme III: Population indicatorsPresentationA New Era of Ageing Spiny Dogfish (Squalus suckleyi) in the North Pacific Ocean

​Shark, vertebrae, ageing, fin spines

Beth Matta, Christopher Gburski, Walter Bubley​

  
MatthiasVignon
Otoliths have long been used for annual age and growth estimates but it have been increasing interest in the use of otolith shape as a natural tag of fish stocks because it provides a practical basis for stock separation that is useful in fisheries management. It is indeed currently recognised that wide range of environmental and genetic factors lead to otolith shape variation and the challenge for the future of morphometric stock identification is to develop a consensus on biological interpretations of otolith shape variation. Since otoliths have received considerable attention, it is fundamental to identify and quantify the relative contribution of the main factors that affect their shape variability. However, to date, there are few comprehensive reports that have examined simultaneously these different factors at multiple scales in natural conditions. In this study, I disentangled sources of otolith shape variation across hierarchical spatial and taxonomic scales. Specifically, a comparative, morphometric study was made based on thousands sagitta otoliths from 8 species (Serranidae and Lutjanidae exclusively) in the Pacific Ocean. The effect of environmental, intrinsic and taxonomic factors on otolith shape variability was investigated, reflecting the likelihood of factor that one can detect when otolith shape is affected by multiples components. For this purpose, I propose a new hierarchical partitioning method embedded in a geometric morphometric framework. While large-scale variations are expected to be associated with important shape variation, this study provides the first quantitative demonstration that local environmental variables contributes equally to total shape variation than large-scale patterns. More generally, understanding of the scaling of otolith shape variation is critical for the use of otolith morphology as an effective tool to improve our understanding of the integrity of fish populations and the management of fisheries resources.
UMR ECOBIOP, INRA/UPPA

​UFR Côte Basque, Allée du parc Montaury

​Anglet

64600France+33 5 59 57 44 48matthias.vignon@univ-pau.frWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPresentationDisentangling and quantifying sources of otolith shape variation across multiple scales using a new hierarchical partitioning approach

​Geometric morphometrics; Otolith morphology; morphological disparity; morphospace; hierarchical partitioning; multiscale determinants.

  
MatthiasVignon
During the last decades, ecologists have paid a great deal of attention to the proper techniques to track fish movement in the wild. In this context, otoliths have proved useful and became increasingly used in a wide range of species worldwide. Otolith material incorporates elements from the surrounding water in a layered manner that preserves the timing of deposition. Elemental composition along otolith centre–edge transects thus represent a permanent record of the growing habitats experienced by the fish throughout its entire life time. While the analysis of these elements is of primary importance in fishery management and population ecology, the traditional approaches mostly fail to capture the multivariate nature of structural change in time series data. Here, I propose a simple approach aiming at coping with the multi-elemental compositional otolith transect in a multi-scale quantitative manner. More specifically, the proposed recursive partitioning method try to bias the chronological clustering process by accommodating some form of user-specified constraints based on both intra- and inter-groups characteristics. This allows researchers to focus on biologically relevant information (i.e. the one researcher look for and can interpret). Chronological clustering based on recursive partition is easily interpretable and directly applicable to detection of hidden discontinuities in any multivariate time series. In a multi-proxy context, it also provides a powerful exploratory tool for assessing the relative importance of cross-correlated variables in structuring the environmental histories, as well as the congruency between variables. Ultimately, approach demonstrates the actual interest in using advanced processing techniques to fully exploit the rich potential of individual biological archives, such as fish otoliths, to characterize individual life history. This appears as a promising new tool for ecologists wishing to extract environmental histories sclerochronological structures and would be a great help for practitioners working with chemical fingerprints.
UMR ECOBIOP, INRA/UPPA

​UFR Côte Basque, Allé du parc Montaury

Anglet

64600France+33 5 59 57 44 48matthias.vignon@univ-pau.frTheme IV: Individual indicatorsPresentationExtracting environmental histories from sclerochronological structures - Recursive partitioning as a mean to explore multielemental composition of fish otolith

Regression tree, chronological clustering, multivariate time series, chemical fingerprints, life history, trace elements, LA-ICPMS.

  
StephenSwearer
Otolith elemental profiles of larval fishes have great potential to provide insight into the environmental conditions experienced during larval development, particularly in areas which experience spatial gradients or heterogeneity in physico-chemical properties of water. Here were explore stitching otolith elemental profiles from larval fish to generate longer time series of environmental histories to assess the extent to which otoliths record changes in water mass properties in bay versus open coast pelagic environments during the larval period in a temperate reef fish. Using dynamic regression models, we show that high-resolution time series of larval otolith chemistry do reflect changes in local environmental conditions, providing a new approach for shedding light on the dispersal ecology of fishes.
University of Melbourne

​Department of Zoology

​Parkville, VIC

3010Australia+61 3 9384 3135sswearer@unimelb.edu.auTheme I: Environmental indicatorsPresentationA stitch in time: using chemical chronologies from otoliths to reconstruct larval dispersal environments

​Dendrochronology, Environmental Reconstructions, Larval Dispersal,​Microchemistry 

​Jeffrey Shima

  
StephenSwearer
The replenishment of benthic marine populations is the culmination of many processes that influence the production, dispersal, settlement and survival of larvae to maturity. Although there have been recent advances in our understanding of dispersal and its importance to population connectivity, to date no study has attempted to evaluate all early life-history processes to assess their relevance to the maintenance of marine metapopulations. Using a model temperate reef fish species, the southern hulafish (Trachinops caudimaculatus), we present data on larval vertical distributions, larval settlement behaviour from choice experiments, and spatial population structure and integrate these empirical results into a coupled biophysical connectivity framework. We then compare modelled estimates of connectivity to larval dispersal patterns from otolith microchemistry. Our findings reveal that realistic estimates of connectivity depend on a high degree of biological complexity, highlighting the importance of empirical validation of biophysical models of larval dispersal
University of Melbourne

​Department of Zoology

​Parkville, VIC

3010Australia+61 3 9384 3135sswearer@unimelb.edu.auTheme III: Population indicatorsPresentationRealizing connectivity- the influence of early life history on the dynamics of marine metapopulations

​Natural tags, olfactory cues, Port Phillip Bay, recruitment, larval retention, self-recruitment​

​John Ford, Emily Fobert, Eric Treml

  
FletcherWarren-Myers
STABLE ISOTOPE OTOLITH FINGERPRINT SIGNATURES:  A MASS MARKING TECHNIQUE FOR FARMED ATLANTIC SALMON Salmo salar

Fletcher Warren-Myers*, Tim Dempster*, Per Gunnar Fjelldal**, Tom Hansen** and Stephen E Swearer*

*Department of Zoology, University of Melbourne, Parkville, Victoria, Australia 3010
**Matre Aquaculture Research Station, 5984 Matredal, Norway
Understanding the ecological and genetic effects of fish escapees from aquaculture facilities on wild fish stocks requires the ability to trace escapees. This is currently difficult due to the lack of a cost effective, mass marking technique that differentiates wild from farmed fish and traces escaped fish back to the farm of origin. We investigated three stable isotope otolith fingerprint mark delivery techniques for mass marking farmed Atlantic salmon (Salmo salar) to determine if they could achieve unambiguous marks with 100% accuracy. Otolith fingerprint signatures created with barium, strontium and magnesium isotopes were delivered via: 1) Maternal transfer: where an isotope marker is injected into broodstock, and thus in turn passed on to the offspring; 2) Egg immersion: where fertilised eggs are left to swell in a solution containing an isotope marker; and 3) Vaccination: where the isotope marker is combined with a vaccine and injected into fish. Analyses of otolith signatures were carried out on a Varian Inductively Coupled Plasma Mass Spectrometer (ICP-MS) fitted with a HelEx (Laurin Technic and the Australian National University) laser ablation (LA) system constructed around a Compex 110 (Lambda Physik) excimer laser. 100% marking success was achieved with all three techniques at specific marker concentrations and all techniques are capable of creating marks that cannot be confused with marks in wild fish. Mark success was dependent on type, concentration, and combination of isotope markers used. In addition, no measurable side effects of stable isotope marking on fish growth, condition, or mortality were observed. The most promising technique, vaccination, can produce multiple fingerprint signatures for as little as 0.1 US cents per fish. We conclude that mass marking farmed Atlantic salmon with stable isotope otolith fingerprint signatures is a viable method to identify and trace farmed escapees
University of Melbourne

​Parkville

​Melbourne, Victoria

3010Australia+61 420243730fwwm@student.unimelb.edu.auPresentationSTABLE ISOTOPE OTOLITH FINGERPRINT SIGNATURES:  A MASS MARKING TECHNIQUE FOR FARMED ATLANTIC SALMON Salmo salar

​Atlantic Salmon, escape, fingerprint, isotope, trace

​Tim Dempster

Per Gunnar Fjelldal

Tom Hansen

Stephen E Swearer

  
ChristellePaillon
Mangrove forests are one of the world’s most threatened tropical ecosystems and are strongly connected to coral reefs as many reef fish species use mangroves as nursery habitats. The permanence of these species population depends on whether mangroves are obligatory, important or accessory juvenile habitats. In this study, we used otolith microchemistry combined with underwater visual censuses (UVC) and mangrove cartography to estimate the importance of mangroves for the Indo-Pacific coral reef fish Lutjanus fulviflamma in the archipelago of New Caledonia. Fish were collected in mangrove and reefs at 11 sites around the island. LA-ICP-MS analyses of otolith edge were used to determine multi-element signatures that discriminate reefs and mangroves. These signatures were then used to reconstruct environmental life history of adults collected on the reefs. We found that all adults displayed a mangrove signature in the juvenile part of their otolith. We also found that individuals presented three different patterns of movement between habitats during their life with the most frequent pattern showing returns to mangrove as adult. UVC and cartography of mangroves confirmed these findings. The analysis of 2942 UVC revealed that the species was absent from isolated islands of New Caledonia archipelago where mangroves were absent. Furthermore, the abundance of L. fulviflamma in an area is highly correlated to the area of mangrove within this area. These results highlight the importance of mangroves for the life cycle of the blackspot snapper in New Caledonia archipelago. They indicate at the same time that mangrove is an obligatory juvenile habitat for L. fulviflamma and emphasize the potential importance of mangrove in the geographic distribution of the species in New Caledonia.
Institut de Recherche pour le Développement (IRD)

​101 Promenade R. Laroque, BP A5

​Nouméa

98848Nouvelle-Calédonie(+687) 97.33.06christelle.paillon@ird.frTheme III: Population indicatorsPosterQuantifying the role of mangroves for the blackspot snapper (Lutjanus fulviflamma) by otolith microchemistry and UVC, in a South-Pacific archipelago (New-Caledonia)

​mangroves, reefs, otolith microchemistry, underwater visual censuses, connectivity, New Caledonia, Lutjanus fulviflamma, essential juvenile habitats

Laurent Vigliola, Laurent Wantiez, Michel Kulbicki, Maylis Labonne

  
AlfHarbitz
Elliptical Fourier Descriptors (EFDs) is probably the most extensively applied technique in shape analysis of a closed contour, with a range of applications within discrimination between fish stocks based on EFDs of otolith contours. A recent technique transforms the 2D contour to a 1D function by mirroring the lower half of the contour around a vertical axis at the right end of the contour. This technique has the advantage of reducing the number of Fourier coefficients to two coefficients per frequency component compared to four with the EFD. The third technique considered is also a 1D technique, based on the tangent angle to the contour at equidistant distances along the contour. This technique also needs only two coefficients per frequency component. All techniques, however, require several frequency components to reproduce a pure ellipse properly. This is due to the applied concept of a constant speed along the contour in the EFD case, equidistant “time steps” in the 1D mirror technique and equidistant contour distance sampling in the 1D tangent angle technique. This contribution shows how these techniques can be easily modified by relaxing on the “equidistant” sampling approach, resulting in a virtually perfect reproduction of a pure ellipse with only one frequency component. In addition, the modification gives better approximation to the original contour with fewer coefficients than the original techniques. Results are demonstrated on Greenland halibut as well as cod otolith samples.
Insititue of Marine Research

Sykehusveien 23, PO Box 6404​

​Tromsø

9294Norway+47 93432615alf.harbitz@imr.noWorkshop on otolith shape analysis (number of participants is limited to 25). Admission will be confirmedPresentationA conceptual improvement of three Fourier techniques to represent 2D closed contours

​shape analysis, Fourier techniques, Greenland halibut otoliths, cod otoliths​

  
Luis A. Quijano-Puerto
The lionfish (Pterois volitans), a native reef fish to the Indo-Pacific Ocean, was introduced in the Atlantic Ocean 30 years ago where it has now invaded a great portion of this region, and represents an environmental threat because of its population growth. In the Southern Gulf of Mexico, off the northern coast of the Yucatan Peninsula, specifically in the Parque Nacional Arrecife Alacranes (PNAA), the lionfish invasion is at an advanced level; however, there have not been studies of lionfish’s corporal growth in the area. Consequently, the objective of this work was to determine its age and growth, as determined by using sagittal otoliths, and calculate both the Von Bertalanffy and Gompertz growth functions. From 2010 to 2012, about 800 lionfish (97 mm to 384 mm TL) were collected from which 609 whole sagittal otoliths were removed and prepared for reading. Preliminary data would be presented in this work, which represents a baseline for future studies on lionfish’s population dynamics to understand the invasive process in the region.
Universidad Autónoma de Yucatán

Departamento de Biología Marina, Campus de Ciencias Biológicas y Agropecuaruas, Universidad Autónoma de Yucatán, Km. 15.5, carretera Mérida—Xmatkuil, A.P. 4—116  Itzimná 

Mérida, Yucatán

97315MÉXICO ​+52 0449992 739287luis.quijano18@gmail.comTheme II: Community indicatorsPosterAge and growth of the invasive lionfish (Pterois volitans) in the Parque Nacional Arrecife Alacranes, Southern Gulf of Mexico

Lionfish, Yucatan Peninsula, coral reef, Pterois volitans, age, growth,  ​​

Beatriz Morales-Nim

Alfonso Aguilar-Perera