Cod A 'Resilient' Fish, Researchers Say

November 14, 2007

Release from: CBC News Online (Canada)

The Atlantic cod is one tough fish, capable of surviving changes in climate, a team of researchers from the United Kingdom, United States and Norway suggest in new research released Wednesday.

In the study, published online in the journal Proceedings of the Royal Society B, the scientists found that cod survived the extreme conditions of the last glacial maximum period approximately 21,000 years ago.

Using computer modelling, the researchers estimated where cod populations could have survived and reproduced during the low temperatures and low sea levels of the last ice age. The simulation found that while the total habitable area of the ocean had been restricted, the fish could have continued to live in Atlantic Canada, New England and stretches of mainland Europe.

Researchers confirmed those findings, the report said, by comparing genetic analyses of present-day cod populations from Canada, Greenland, Iceland and Europe.

"Both the Canadian and the European populations of Atlantic cod appear to have survived at least one full glacial cycle," the report said.

The scientists said the findings could help in determining how vulnerable the fish will be to future global warming.

But Grant Bigg, of the University of Sheffield in the United Kingdom, said the team's findings do not show the future survival of the species is guaranteed.

"This research shows that cod populations have been able to survive in periods of extreme climatic change, demonstrating a considerable resilience," he said in a release. "However, this does not necessarily mean that cod will show the same resilience to the effects of future climatic changes due to global warming."

The report elaborates on Bigg's point, saying, "The effects of future climatic conditions need to be considered in relation to demographic structures as well as the major population changes due to human exploitation."