Cod set to vanish from North Sea under global warming

Published on Wednesday 9 September 2009 22:08

COD will eventually disappear entirely from the North Sea as a result of climate change, a report by marine scientists warns.

Dramatic changes in the abundance of plankton, caused by global warming, have led to a decline in cod stocks in the North Sea, according to a study published in the Proceedings of the Royal Society Biological Sciences journal.

In the past 40 years, the average temperature of the North Sea has increased by 1C, forcing species of plankton, on which cod larvae feed, to move away in search of cooler waters.

The report's authors, Dr Richard Kirby, of Plymouth University, and Dr Gregory Beaugrand, of France's Centre National de la Recherche Scientifique, warn that stricter quotas or even a blanket ban on fishing will not be enough to save existing stocks of North Sea cod.

Dr Kirby said: "The plankton that young cod usually eat during March, April and May, a species of copepod that is the size of a grain of rice, prefer cold water and so they have become much less frequent as the North Sea has warmed.

"These copepods have moved north by about 1,200 kilometres (745 miles], or 30km per year, and the plankton replacing them come later in the year, which is no good for the young cod. The cod will not simply move north to follow the plankton, however, because the water there is too deep."

He added: "If the increase in global temperatures projected by the Intergovernmental Panel on Climate Change continues, cod will inevitably disappear as a commercial species in the North Sea, whatever the reduction in fishing.

"However, new areas, such as the Barents Sea, may become a habitat for cod."