Atlantic Fish Crisis May Be Due to Global Warming
January 9, 2002
Scientists at the University of East Anglia (UEA), U.K., are involved in
a major research project investigating a possible link between global
warming and falling numbers of cod.

A team from the UEA is currently analyzing sea samples containing zooplankton, the tiny marine animals that are the staple diet of the fish and other species such as haddock.

Researchers on board the science vessel Discovery collected the samples at 17 sites from the ocean surface to within a few hundred meters of the sea floor in the northern Atlantic between Greenland and Iceland.

Current flows and the water chemistry were also analyzed.

The (British) 6.5 million pound (U.S. $10 million) study by the National Environment Research Council (NERC) was prompted by concern about dwindling numbers of fish stocks.

Tracking Zooplankton

Previous studies in the North Sea have shown a 90 percent decline of zooplankton in the past 40 years at a time when cod, haddock, herring, and mackerel levels have also fallen, fuelling speculation that overfishing may not be the sole cause of their decline.

And experts are keen to discover if a similar pattern is being repeated in the Atlantic waters.

One theory being investigated is that rising water temperatures could be affecting ocean circulation patterns, moving the shrimp-like creatures north into waters away from traditional fishing grounds.

Phil Williamson, a UEA marine biologist coordinating the research, said that early findings suggested that levels of zooplankton were also dropping in the Atlantic, which could have an impact on the rest of the food chain.

"The numbers seem to be lower than what we expect but it's very difficult to know what to expect when we haven't done a study like this before. It's early days but we have got some indications from some surveys that the numbers might have gone down a bit," he said.

Cause Unknown

Further studies were to be carried out as part of the project in a bid to confirm if the drop was climate linked or a coincidence. "In six months to a year we will certainly be more confident in answering that," Williamson said. "We want to know where they are moving to and where water currents are taking them."

And although the cause of the decline is yet to be determined, its effect is sure to be another blow for the commercial fishing fleet.

"If ocean currents change then zooplankton is going to change and usually where there are changes things suffer before they get better," Williamson said.

Copyright 2001 Eastern Counties Newspapers Group Ltd.

© 1996-2008 National Geographic Society. All rights reserved.