A model for evolving fish stocks in a stochastic environment

Institute of Marine Research, Bergen, Norway

Sondre Aanes

Sondre Aanes

A number of fish stocks have exhibited changes in age and size at maturation after exposure to heavy exploitation. This is consistent with theoretical studies that have demonstrated increased harvesting pressures to select for earlier maturation. Earlier maturation, in turn, is likely to result in a decrease of total yield. Such a decrease in age and size at maturation has been observed in the Northeast Arctic cod. This stock is the most economically important fish stock in the Northern Atlantic and one of the most productive fish stocks worldwide. During the last century, the Northeast Arctic cod has not only experienced changes in exploitation pressure and pattern, it has also been exposed to a fluctuating ocean climate and to a varying biological environment. For this and other reasons is not easy to determine the actual cause of the observed changes in cod maturation. By incorporating documented environmental variations into ADN's existing age-, size-, and genotype-structured cod model we expect to disentangle the effects of different variations and thus to explain what is causing the described changes in the Northeast Arctic cod. Eventually, these analyses can contribute to reducing uncertainty in the assessment of the Northeast Arctic cod stock and will help to clarify whether and how evolutionary change in life-history traits should be accounted for in the sustainable management of renewable marine resources.

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Last edited: 03 June 2016

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