NEW YORK -- A rush of cold fresh water from the Arctic contributed to the collapse of the northwest Atlantic cod industry and is fueling a boom of snow crab and shrimp in the waters off New England and eastern Canada, a new study says.
A reversal of wind direction with a record drop in Arctic air pressure pumped the water through the Canadian archipelago in the late 1980s and 1990s, according to a study in today's issue of the journal Science. The cold water helped spoil the cod habitat while improving conditions for snow crab and shrimp.
As global warming continues to melt Arctic ice, the shifts in temperature and marine life will probably become permanent, Charles Greene, the study's author, said in a telephone interview.
"I don't think we're looking at a future where cod are going to be doing well," said Greene, an ocean scientist at Cornell University. "These changes are going to be good for people who can adjust to them, and for others it's going to be a real hardship."
Some scientists attribute the 75 percent reduction of cod stocks entirely to overfishing, Greene said. Canada was quicker to restrict cod fishing, but US cod have seen a speedier recovery. The Canadian recovery has been slowed as the cold Arctic flows have made the northern range inhospitable to the slow-growing fish, he said.
The cool water comes from a large body called the Beaufort Gyre, which borders the Arctic ice shelf. Clockwise-turning winds build up water from rain and melting ice. About every 10 years, the wind direction reverses, dumping the Beaufort Gyre into the surrounding ocean. Increased rain and melt-off contributed to the record spill.
Melting Arctic ice could continue to drive temperatures down in the northwest Atlantic while temperatures elsewhere rise, Greene said. General expectations of global warming are that species will move north as the earth heats up.
"What's really unusual in our part of the world is that there's real evidence that some species are doing the opposite; their range is shifting to the south," Greene said.