Jan

30

2007
 
 

Chips down for battered cod



cod...pieces!Genetic response to selective fishing hampers stock recovery from collapse

Evolution is a two-edged sword — just ask any Atlantic cod. Having withstood the ravages of decades of overfishing, collapsed populations have been slow to recover, and a study published this week shows why. Cod numbers in the Gulf of St Lawrence dwindled in the 1960s and 1970s but recovered well during the 1980s, only to crash again in the 1990s, since when they have remained at low densities. So why no second cod comeback? Gulf Fisheries Centre, New Brunswick, marine biologist Douglas Swain and colleagues think the increase in mesh size around the late 1970s was crucial, bringing about a fast evolutionary shift in the cod. The change was intended to allow fish stocks to build, but instead seems to have selected for slow growth and thus delayed maturity and reproduction. Swain’s findings show how rapid genetic changes can be: fishermen should ignore the warning at their peril!

Source: Swain, DP, Sinclair, AF & Hanson, JM (2007) Evolutionary response to size-selective mortality in an exploited fish population. Proceedings of the Royal Society of London, Series B. DOI: 10.1098/rspb.2006.0275

Filed Under Endangered species, Restoration, Marine, Monitoring, Economics and conservation | 

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