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On board the R/V Arni Fridriksson for the International Ecosystem Summer Survey in the Nordic Seas

Scientists blog from the International Ecosystem Summer Survey in the Nordic Seas.
Published: 25 July 2019

​​Each summer, five countries use six research vessels for six weeks to carry out the International Ecosystem Summer Survey in the Nordic Seas (IESSNS). Vessels from Iceland, Denmark, the Faroe Islands, Greenland, and Norway are currently in the latter part of the survey.

The Icelandic R/V Arni Fridriksson departed Reykjavik on 3 July and expects to return to Reykjavik on 1 August. The crew have been documenting the progress of the vessel live and blogging their experiences.

W​e spoke to Anna Olafsdottir, Marine and Freshwater Research Institute and survey leader, ​about what the IESSNS involved.

"The core monitoring programmes remain the same from year-to-year. The IESSNS core programme involves measuring the abundance and distribution of mackerel, Norwegian spring-spawning herring, blue whiting, lumpfish, and Atlantic salmon.  Additionally, most of the six vessels collect samples for various research projects for their home institutes." 

Since 2014, the survey area has remained similar and the distance between the predetermined surface trawl stations is constant. However, station locations change each year. The location of the first station in each stratum is calculated using randomization and the other stations located at a set distance from the first one.

According to Olafsdottir, the diversity of her workday keeps life at sea interesting. "Definitely, I need to follow up on all the many and various projects, do my shift in the acoustic lab, as well as maintaining a great working relationship with the crew.​

Unexpected challenges will pop up each year. "There are always unforeseen challenges, including summer storms, drift ice, damages to the standardized swept area trawl, and emergency rescue. Participating in the rescue of three people from a yacht during a storm is one of the most memorable during my three years on the job. Staying on schedule when working in such an unpredictable environment is always a major challenge"​.

While the crews of the other vessels involved in 2019 IESSNS do not blog, they have participated in a live online map of vessel progress for the first time this year. "Obtaining the permits to display the location of foreign vessels was a lot of work! It took two attempts to climb the mountain of international paperwork needed, but we got there thanks to determination of my coworkers Sigurður Jónsson and Einar Hjörleifsson​".

What is the aim of the survey?

Each vessel participating in the IESSNS carries out sampling for a core monitoring program which provides:

  • An annual age-segregated abundance index using surface trawling at predetermined positions, with an uncertainty estimate, for northeast Atlantic mackerel. The index is used as a tuning series for stock assessment.
  • A timeseries for the blue whiting abundance index and for Norwegian spring-spawning herring abundance index using hydroacoustic methods.
  • Monitoring of other species, such as lumpfish and Atlantic salmon, are also monitored. All catch is sorted to species and measured.
  • Measurements of temperature and salinity from surface–500m depth at each surface trawl station.
  • An index for zooplankton abundance, measured by using a WP2-net from surface–200m depth at each surface trawl station.

The Icelandic crew are carrying out additional sampling for various national and international research projects This year's projects are:

  • ​Tagging live lumpfish (the Greenland vessel also participates).
  • Collecting environmental DNA by filtering seawater from various depths.
  • Measurements of chlorophyll and nutrients from seawater samples at various depths.
  • Collecting stomachs and measurements of mackerel, herring, and liver weight of blue whiting to research their somatic condition and feeding.
  • Species identification, measurements, and freezing of all fish and invertebrates caught in the mesopelagic layer during acoustic ground-truthing trawls.
  • Preservation of gills of Icelandic summer spawning herring for DNA analysis.
  • Freezing of herring hearts for parasite monitoring.
  • Freezing of capelin for gonad to research in any of them spawn more than once.
  • Collecting blue whiting and mackerel stomachs for micro-plastic research.
  • Opportunistic registration of whales (the Norwegian vessels also participate),
  • Registration of all plastic and other garbage caught in the trawl.
  • writing the blog​!

Where are the results used?​

Each year, following the survey, participants from the six vessels will meet, compile the catch numbers, acoustic data, and environmental data from all vessels, and analyze the data.

Information about the survey (design, coverage, sampling programme) and the survey results (including age-segregated biomass index for mackerel, herring,​ and blue whiting) are first presented at the stock assessment meeting of the ICES Working Group on Widely Distributed Stocks (WGWIDE).

Results of the 2019 IESSNS survey will be made publicly available during the 2019 WGWIDE meeting scheduled for 28 August​–3 September. The results of the 2018 IESSNS survey are available to view on the blog entry for 21 July.

This work contributes to ICES science priority​ on​ Observation and exploration which involves monitoring and exploring the seas and oceans to track changes in the environment and ecosystems and to identify resources for sustainable use and protection.




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 Anna Olafsdottir, ​survey leader, tagging lumpfish on the Icelandic section of the International Ecosystem Summer Survey in the Nordic Seas.

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On board the R/V Arni Fridriksson for the International Ecosystem Summer Survey in the Nordic Seas

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