WorkPackage 7. Sea mammals and their population increases in the Northeast Atlantic - its effects on the population dynamics relevant for the MSE methods applied.

There seems to have been a mega-trend in the stock biomass and fish consumption of sea mammals in the Northeast Atlantic the past half a century. Some estimates indicate that sea mammals are now eating about 12 million t per year of fish in this sea area and compared to the commercial catch of 10 million t this could potentially be important for fisheries management, meaning that Fmsy should be reduced. Data on sea mammal stock development by species and food items consumed, are sparse so only rough estimates will be possible.

A comparison will be made to the Northwestern Pacific where there are indications that the reason for the large annual catches there of 20-30 million t are due to fishing down large fish and thus reducing predation on small forage fish, boosting the catches of these. However, it could be speculated that maybe changes in sea mammal biomass might also contribute. This will be considered on a macro-ecological scale.

We will especially consider the effect on the selected six stocks in the current project.