A rapid warming of the Gulf of Maine off the eastern United States has made the water too hot for cod, pushing stocks towards collapse despite deep reductions in the number of fish caught, a U.S. study showed on Thursday.
The Gulf of Maine had warmed faster than 99 percent of the rest of the world's oceans in the past decade, influenced by shifts in the Atlantic Gulf Stream, changes in the Pacific Ocean and a wider trend of climate change, it said.
Scientists said the findings showed a need to take more account of changing water temperatures in managing global fish stocks usually based on historical data of catches.
Traditional calculations "consistently over-estimated the abundance of cod," said Andrew Pershing, chief scientific officer of the Gulf of Maine Research Institute and lead author of the study in the journal Science.
"Rapid changes outpaced our ability to recognize and react to what was happening in the water," he told an online news conference.
Fisheries managers cut cod quotas in recent years but cod numbers kept falling because the rapidly warming waters were making the Gulf of Maine inhospitable for the fish.
From 2004, temperatures rose by more than 0.4 degrees Fahrenheit a year, culminating in an ocean heat wave in the northwest Atlantic in 2012-13.