RESULTS of the recently completed INFERNO project suggest that the size of planktivorous fish species – herring, blue whiting and mackerel – feeding in the Norwegian Sea has reduced.
The results have been published in the current issue of the journal Marine Biology Research, and find that, during 2000-2009 there was a downward trend in zooplankton biomass, meaning less food for all fish. Changes in fish migration patterns, temperatures, horizontal and vertical distribution, variability in the abundance of food as well as seasonal and lifecycle trends in feeding also had the potential to affect the three species. The studies confirmed the original hypothesis: “all the stocks showed signs of density-dependent length growth, whereas for herring and blue whiting there were also significant effects of interspecific competition.”
As a result of the nine papers and related research presented in this special issue, marine scientists will not only have a better idea of what’s happening under the waves of the Norwegian Sea, but also how future trends can be predicted. Several of the papers address the use of 3D and Individual-Based Models (IBMs) to estimate the horizontal and temporal overlap of fish and the amount of food they might consume. As the authors note, the models can be widely applied: “Individual-based ecosystem modelling systems try to thoroughly integrate differences among species, populations, size/year classes, and habitats in temporally and spatially dynamic algorithms aiming at generating predictions on larger-scale ecological processes and changes.”
Although the specifics of the data and the modelling presented relate to the Norwegian Sea, the authors intend that their work should reach a wider audience, firmly believing that it “may represent a very valuable example of what could be applied in many other marine ecosystems”. The authors also feel that “it will be important to include these findings in the future ecosystem based management of the Norwegian Sea”; this special issue of Marine Biology Research is thus essential reading for conservationists, marine biologists and anyone with an interest in commercial fisheries or our northern seas.