Quantcast

“Red Devil” squid, jellyfish point to ocean upsets

August 20, 2006

By Alister Doyle, Environment Correspondent

OSLO (Reuters) – South American “Red Devil” squid found off
Alaska and jellyfish plaguing the Mediterranean may point to
vast disruptions in the seas linked to global warming,
pollution or over-fishing, experts say.

Fish such as salmon and mackerel have also been spotted in
the Arctic, far north of their normal ranges, in a possible
vanguard of wrenching billion-dollar shifts in world fish
stocks this century caused by warming oceans.

“There will be some places where ocean productivity will
increase,” said Ron O’Dor, senior scientist of the Census of
Marine Life, a 10-year project in more than 70 nations to map
the diversity of the oceans.

“The story of global warming is going to be good for some
people and bad for others,” he added.

Many scientists say that gases emitted by burning fossil
fuels — coal, gas and oil — are blanketing the planet and
driving up temperatures, threatening to spur more floods,
heatwaves, erosion and rising sea levels.

Warmer oceans are likely to add to older marine threats
such as pollution and over-fishing and upset the habitats of
everything from crabs and Mediterranean jellyfish to “Red
Devil” squid and whales.

As species shift, tropical regions, or almost enclosed seas
such as the Mediterranean where fish cannot swim far if the
water gets uncomfortably warm, may be among the most
vulnerable.

“Areas close to the equator will most likely be the losers
while the northern or southern areas might be the winners,”
said Harald Loeng, head of research in oceanography and climate
at the Norwegian Institute of Marine Research.

“It’s most likely that some of the species in the North Sea
like cod will move north … and be replaced by anchovies and
sardines,” he said.

Some studies suggest that the Arctic sea ice, for instance,
could melt in summers by 2100. As ice recedes, the extra heat
and sunlight will help plankton grow and so feed more fish.

ON THE MOVE

Humboldt or “Red Devil” squid, which can weigh 40-50 kg
(88-110 lb) and originated off Peru, were caught off Alaska for
the first time last year after sweeping north, O’Dor said.

Around the same time, other scientists found specimens of
the jumbo squid, growing up to about 2 meters (6 ft 7 in) long,
in southern Chile.

Over-fishing of more valuable fish stocks might be partly
to blame for the squid population explosion by upsetting the
food chain along the Pacific coast of the Americas.

“As you remove the really big predatory fish like the big
tuna and the marlin and the swordfish there are no predators in
the water that can eat something as big as a 40 kg squid,
except a few whales,” O’Dor said.

And a spate of jellyfish stinging holidaymakers on
Mediterranean beaches this summer, for instance, may be part of
wider changes such as global warming, or merely a freak.

The boom could be linked to a decline of predators such as
turtles because of pollution — turtles sometimes choke on
plastic bags which they apparently mistake for billowing
jellyfish floating in the water.

And salmon have been caught north of the Bering Straits
between Russia and the United States in recent years. They have
also swum from the north Atlantic to once icy seas off northern
Canada.

RISING SEAS

“It seems pretty clear that (the salmon in the Arctic) has
to be climate change. The conditions there have never been
suitable for these animals before,” said O’Dor.

Among other changes, tropical coral reefs could die off in
warmer waters. Many reefs, often known as “nurseries of the
seas” are struggling with higher temperatures.

And U.N. studies project that global sea levels could rise
by 9 to 88 cm (3.5 to 34.6 inches) by 2100. That could cut the
amount of sunlight reaching slow-growing corals, which co-exist
with light-dependent algae.

Meanwhile, a slightly more acid sea linked to a build-up of
greenhouse gases in the atmosphere could make it harder for
creatures like lobsters or oysters to form shells. They might
end up too soft and vulnerable to predators.

Still, fish stocks have often varied mysteriously.

In 1599, for instance, herring failed to appear along the
Norwegian coast. The locals widely believed that God was
unhappy because of thieving, drunkenness and fighting among
fishermen.


Source: reuters



comments powered by Disqus