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Evolutionary effects of fishing

In the latest issue of Science, the leading American research journal, scientists from IMR and the University of Bergen together with colleagues across Europe, draw attention to the evolutionary effects of fishing.


By Erin S. Dunlop, Katja Enberg David Boukal and Mikko Heino

The article presented in the journal’s Policy Forum emphasizes that fisheries management should consider the evolutionary consequences of fishing, and discusses how evolutionary changes might influence, for example, recruitment processes or pre-cautionary reference points. In other words, the authors argue for the compelling case of adopting evolutionary enlightened management.

Authors Christian Jørgensen, Katja Enberg, Erin S. Dunlop, Mikko Heino, and David Boukal (left to right in above picture), introduces Evolutionary Impact Assessment as a new tool for evaluating the effects of fisheries-induced evolution on the utility derived from fish stocks. These assessments can be relatively simple, relying on available fisheries time series data, or more elaborate, utilizing evolutionary models to investigate how the utility derived from a stock develops under a given management strategy.

Why do we need it?

Commercially harvested fish stocks are subject to high rates of exploitation. In some cases, the mortality caused by fishing can exceed natural mortality by more than 400%.  Such high mortality rates not only have an impact on population abundance, but can also have more hidden, and often overlooked, evolutionary effects.  By drastically reducing survival to the next reproductive season or by selectively removing fish with certain characteristics (e.g., large body size), fishing can induce genetic changes in key life-history traits such as maturation age and size, growth rate, and reproductive investment.  The evidence for fisheries-induced evolution is mounting: trends indicative of contemporary evolution have been detected in many commercial stocks including Northeast Arctic cod, Northern cod, and North Sea Plaice.  Furthermore, such evolutionary changes can unfold within a matter of years, cause reduced body sizes of fish in the catch, and potentially take a long time to reverse.  Presently, however, fisheries management does not include consideration of fisheries-induced evolution.

New ICES Study Group

Scientists are now studying the most effective ways of dealing with fisheries-induced evolution in fisheries management. The International Council for Exploration of the Sea (ICES) recently established a Study Group on Fisheries-Induced Adaptive Change (SGFIAC) to meet this challenge. This group met for the first time in Lisbon in February 2007. Mikko Heino is one of the three Study Group chairs together with Ulf Dieckmann (Austria) and Adriaan Rijnsdorp (The Netherlands).