Fish migrating to cooler waters, study says

By Azadeh Ansari
CNN

(CNN)
-- Climate-driven environmental changes could drastically affect the
distribution of more than 1,000 species of commercial fish and
shellfish around the world, scientists say.

Red areas on this map show regions that are expected to have the greatest increase in fish populations by 2050.

For the first time, researchers using computer models have been able to
predict the effect that warming oceans, fed by greenhouse-gas
emissions, could have on marine biodiversity on a global scale.

A new study predicts that by 2050, large numbers of marine species will
migrate from tropical seas toward cooler waters -- specifically the
Arctic and Southern Ocean -- at an average rate of 40 to 45 kilometers
(about 25 to 28 miles) per decade.

These migrations could lead to "numerous extinctions" of marine species outside the Arctic and Antarctic, especially in tropical waters, according to the study's projections.

"These are major impacts that we are going to see within our lifetime
and our children's lifetime," said William Cheung, lead author of the
study, set to be published this week in the journal Fish and Fisheries.

"Climate change
provides us with a kick in the pants," added Cheung, a marine biologist
and lecturer at the University of East Anglia in the United Kingdom.
"We can't think about climate change and biodiversity without thinking
about the impact it will have on pe

Researchers from the University of East Anglia, Princeton University
and the Sea Around Us Project at the University of British Columbia
participated in the study.

Using a combination of data from
fisheries and computer models that can project the potential effects of
climate change on biodiversity, researchers were able to make
predictions on the migration patterns of different fish species under
varying climate-change scenarios.

The study predicts that within
41 years, the global distribution of marine species will shift 60
percent as more fish move toward cooler waters near the Earth's poles.

"Even if we completely stop fishing, we will still see a big difference
in 10 years," said Emily Pidgeon, senior technical adviser with the
Regional Marine Strategies Department at Conservation International.

The study suggests that conservationists will have to adapt their
approach to a shifting marine environment. Added Pidgeon, "The goal
posts are changing, so we need to re-think and re-tool the way we look
at fishery management."

The migration patterns outlined in the
study would further diminish the coastal population of the Atlantic
cod, a once-plentiful fish that was a staple of American and European
diets for centuries. According to the study, the worldwide population
of cod could be cut in half by 2050.

"Cod disappearing from New
England is not new, it has been a trend for the last 15 years, said
Mark Kurlansky, author of the book "Cod: A Biography of the Fish that
Changed the World." "It's interesting to see that there is something
else besides overfishing that is causing a decline."

The
migration of certain fish species out of their natural habitats could
cause food shortages for millions of people, especially in developing
countries near the equator, who depend on local seafood as a staple of
their diet, scientists say.

"Catch will decline in countries
along the tropics like Malaysia where the conditions are too hot, and
high-latitude countries like Russian and Norway will win," said Daniel
Pauly, director of the Fisheries Centre at the University of British
Columbia in Vancouver, Canada.

The migrations could have
economic and political implications if fish eventually drift across
boundaries into waters controlled by neighboring countries, he said.

"If you have fruit trees in your garden, and all of a sudden they move
to your neighbor's garden, you can't do anything about it," Pauly said.

The study's authors wrote that they hope their findings "give policy
makers, the scientific community and [the] public a picture of the
potential scale of the problem." They cautioned, however, that because
of the complexity and scale of the issue and the computer modeling used
to study it, "the magnitude of our projections is uncertain."

Cheung and other authors of the study were expected to discuss their
findings this week at the annual meeting of the American Association
for the Advancement of Science in Chicago, Illinois.