August 20, 2006
‘Red Devil’ Squid, Jellyfish Point to Ocean Upsets
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.
"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.