Cod fisheries off the American coast have now largely collapsed, and recent research, by the University of Iceland and Marine Research Institute in Reykjavik, indicates that the remaining commercailly viable fisheries around Iceland are also teetering on the brink.

For a long time we have known that fishing exerts a strong pressure on the size and age at which cod mature. The scientists report that this has resulted in a reduction in the length at which a fish becomes mature by nearly one centimeter per year. The loss in size at maturity has a corresponding loss in fitness, with shallow water fish (the most heavily hunted) having only 8% of the fitness of their deep water counterparts. These changes are almost certainly hereditary, the fish responding to the dead-end that modern fisheries management has forced them into.

The authors speculate that the immediate establishment of large no-take reserves might relieve selection pressures on the fish, and avert a population collapse.

Full article Árnason et al. Intense Habitat-Specific Fisheries-Induced Selection at the Molecular Pan I Locus Predicts Imminent Collapse of a Major Cod Fishery. PLoS ONE, 2009; 4 (5):

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