Water too warm for cod in U.S. Gulf of Maine; stock near collapse

By Alister Doyle
OSLO, Oct 29 (Reuters) - 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 recognise 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 0.23 degree
Celsius (0.4 Fahrenheit) a year, culminating in an ocean heat
wave in the northwest Atlantic in 2012-13.
And commercial cod landings fell to 1,000 tonnes in the Gulf
of Maine in 2013, sliding from a recent high of 6,000 in 2009,
according to the U.S. Department of Commerce.
A U.N. climate report last year said that global warming was
pushing many fish stocks towards the poles. Cod are thriving in
cooler waters such as off Canada, Norway or Greenland.
"The Gulf of Maine cod is a wake-up call" for better
coordination between climate scientists and fisheries
management, said Katherine Mills, one of the authors at the Gulf
of Maine Research Institute.
She said it was unlikely that cod catches would recover to
pre-crisis levels. The experts laid out scenarios that foresaw a
recovery to 5,000 tonnes a year by 2030 in a warm scenario or to
just 1,800 tonnes in a hot scenario.