Thursday 5. November 2009

Spatial-temporal trends in non-commercial fin fish species in Iceland: 1985-2009

A decline in the world fish stocks has been documented through scientific studies during the last 30 years. In recent years fisheries managers have acknowledged that single species management approaches to management ignore the greater ecosystem context, thus fisheries management has shifted from a single species approach to an ecosystem wide approach.

This study uses the data collected from 25 years of scientific trawl surveys to analyze the trends in noncommercial fin fish species, which serve as an ecosystem indicator. 16 species were selected for analysis. Three species (Leptagonus decagonus, Myoxocephalus scorpius, and Cottunculus microps) show a decreasing trend in population size while three species show increasing populations (Rhinonemus cimbrius,, Gaidropsarus argentatus, and Chelidinichthys gurnardus).
Additionally, nine species had a significant change in their geographic center during the time period studied. Three species shifted south (T. murrayi, A atlanticus, and M. scorpius), two species shifted northwest (T. esmarkii and R. cimbrius¬), two species moved south (C. monstrata and C. gurardus), one species migrated north (R. fyllae) one species moved southeast (C. microps).

As would be expected, with current warming water temperatures in Iceland, warm water species tended to increase in population (2 out of 3) and migrated north and west. None of the warm water species´ populations decreased. All species with decreasing populations were cold water species. Interestingly, one cold water species showed a positive trend in abundance and four cold water species had a southern component to their migrations. These last results suggest a role in changing ecosystem regimes and that subtle temperature shifts can influence these species.