ICES 2000 Annual Science Conference
27–30 September 2000
88^th Statutory Meeting, 24 September to 4 October 2000
Brugge (Bruges) Belgium

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Programme

Mini-Symposium and Theme Sessions

Open Lecture and Keynote Lectures

List of Contributions (Papers/Posters)

ICES Homepage

Prof. Dr Daniel Pauly
Fisheries Center
2204 Main Mall
Vancouver, BC V6T 1Z4
CANADA
e-mail: pauly@fisheries.com

There are two disciplines presently working on the status of marine organisms: Fisheries Science, founded at the end of the 19th century as a very applied discipline, and Conservation Biology, founded at about the same time as a terrestrial discipline, but which turned its gaze to marine organisms and ecosystems only recently. These two disciplines – like all scientific ventures – have their own standards and aims, as articulated by leading practitioners, and their seminal contributions, in specialized journals. Unfortunately, these parallel tracks lead to many misunderstandings starting with mutual lack of recognition for each other’s achievements, and often ending in unprofessional behaviors.

This lecture will present a case for reconciliation, based on (1) the reduced state of most exploited fish populations, leading to a consensus on the need for wide-ranging fishing effort reduction; (2) the emergence of Marine Protected Areas as a management tool for both rehabilitating fisheries and protecting biodiversity; (3) the emerging consensus that fisheries management, somehow, need to be concerned about ‘ecosystem issues’ ; (4) increasing public interest about the ‘health’ of the oceans, and thence for the disciplines that are (or should be) concerned with this and related issues, notably global climate change (5) limited funding for science in general, and for the research required to address (1) to (4). A large multidisciplinary research project, recently initiated to address these issues on a basin-wide scale, and evaluating the impacts of fisheries on the ecosystems of the North Atlantic will be presented. Some of its preliminary results will be used to illustrate how fisheries and conservations issues may be tackled simultaneously, and solutions identified which, if implemented, would benefit both sets of ‘clients’.

Dr Patrick Gentien
IFREMER Centre de Brest
B.P. 70
29280 FRANCE
e-mail: pgentien@ifremer.fr

Gymnodinium mikimotoi is an ubiquitous ichtyotoxic dinoflagellate species causing harm in the North Sea, the Atlantic, Japan, South America, and South Africa. Its blooms have deleterious effects on marine aquaculture stocks (fish and shellfish), on species recruitment (shellfish and probably fish), and possibly on marine flora and ecosystems.

Toxicity of this species is due to a labile exotoxin (20 min. half-life time). Synthesis of this exotoxin enables determination of the mechanism of action for this toxin: it inhibits in a non-specific way membranes ATPases. These enzymes are the energy source for ion exchanges at membranes. Biological targets are, therefore, incapacitated in their osmotic pressure regulation. The effect of these exotoxins have been studied in terms of economic losses, but never in terms of the effects on the ecology and the development of a bloom. The spatial scale of action in relation to degradation is of the order of a few centimeters. Since individual cells have been observed to aggregate during the growth phase of the population, it is very likely that the population creates its own specific environment.

In order to define the specificities of this environment in terms of population dynamics, the effect of the toxins on different control (or hexicological, according to the definition of Miwatt) factors have been examined.

Oxygen radicals produced by decay of the toxin can only optimize the organic matter uptake. Allelopathic properties of the toxin have been demonstrated and reduce competition for substrate. Toxins and the mucus produced by the dinoflagellate population lowers the grazing pressure. On the other hand, though less sensitive than their competitors, G. mikimotoi cells are sensitive to their own toxins. Cells have developed an anti-collision system, effective in still environments, which is proven not to act above a certain threshold of turbulence.

Based on the hierarchization of the processes, a simple formulation of population growth has been used to simulate hindcast time-series in the Bay of Biscay (France). The zone of inoculation of the population was defined from different scenarios using analysis of trajectories. The results of the modelling exercise are compared to the time-series obtained from the monitoring network in terms of confinement on the vertical, timing of events and geographical extent.

Omission in this model of any growth limitation by nutrients and the advantages in using a "species-of-interest" approach are discussed.

Dr Ann E. Gargett
Institute of Ocean Sciences
P.O. Box 6000
Sidney, B.C. V8L 4B2 CANADA

There is increasing evidence that extremes in climate variability correlate with major changes in coastal ecosystems, culminating in large variations in marine fish stocks. Any such correlations presumably arise through effects of atmospheric forcing on ocean processes, which in turn shape the environment in which biological systems function. Climate-induced changes in physical ocean processes could exert "control" over zooplankton production (i) from below, if physical processes set the level of primary production available to support higher trophic levels, (ii) from within, if physical processes determine zooplankton growth rates, or (iii) from above, if physical processes affect the rate at which zooplankton are themselves cropped. These possibilities are explored using a simple N-P-Z biological model coupled to a physical box model of the Strait of Georgia/Haro Strait/Strait of Juan de Fuca system of southern British Columbia. Model results indicate that while observed levels of interannual variation in the physical forcing of this system reproduce observed levels of variability in the annual cycles of characteristic physical parameters such as salinity, stratification, etc., there is very little associated variation in the embedded biological system. However large changes in annual cycles of biological variables are observed; comparable changes can be produced in the model by relatively minor changes in biological rate parameters (phytoplankton growth rate, zooplankton feeding rate, and/or mortality rate). Thus, model results strongly suggest that climate variability does not affect estuarine ecosystems directly, i.e. by effects on advective flows, nutrient supply rates etc., but rather indirectly, through modification of characteristics of the physical environment which affect crucial biological rate parameters. In strongly estuarine systems, turbidity changes associated with variability in freshwater forcing is a likely cause of such rate modification.