Overfishing has cut deeply into the North Sea's cod population in recent decades, and scientists now say this important food fish faces a second challenge — climate change.
North Sea water temperatures have climbed 1 degree Fahrenheit over the past 100 years, and that has shifted currents, carrying a major food source, plankton, away from the cod, said scientist Chris Reid of the Partnership for Observation of the Global Oceans in Plymouth, England.
"The only way that these increases can be explained is by greenhouse gas emissions," Reid said. In their larval stage, the cod feed on the minute plants and animals known as plankton. Chances of survival without them are slim.
North Sea cod that do survive today are smaller and less successful at mating and reproducing, Reid explained.
In addition, warmer temperatures increase cod metabolism and the larvae’s need for nutrition, he and other marine scientists noted in a 2003 research paper.
Because the European Union's 2003 cod recovery plan isn't working, scientists and fishing industry representatives are seeking new ways to counter the threats and help the cod.