MIAMI - Unusual warming in the waters off the northeastern US state of Maine has killed off vast numbers of cod, further endangering a valuable and iconic fishery despite years of fishing restrictions, researchers said Thursday.
New England cod stocks are on the verge of collapse, numbering at three to four per cent of what scientists say are sustainable levels.
The problem has been fueled by overfishing, and exacerbated by a stark warming trend that is unparalleled on Earth, researchers said in the journal Science.
The ocean in the Gulf of Maine has "warmed 99 per cent faster than anywhere else on the planet between 2004 and 2013 -- in part due to changes in the position of the Gulf Stream," said the study.
These warming temperatures led to fewer offspring and fewer young fish surviving until adulthood.
Even the effects of a series of restrictions on cod fishing, put in place in 2010 to try to save the population, were outpaced by the warming.
"Managers kept reducing quotas, but the cod population kept declining," said Andrew Pershing, chief scientific officer of the Gulf of Maine Research Institute and lead author of the study.
"It turns out that warming waters were making the Gulf of Maine less hospitable for cod, and the management response was too slow to keep up with the changes."
The struggling Gulf of Maine cod population -- a species that prefers cold water -- has shifted southward over the past 45 years, researchers say.
In contrast, a report out earlier this week found that cod to the north, off the coast of Canada, are rebounding and have made a comeback in recent years.