for National Geographic News
Scientists say urgent international action is needed to safeguard the Southern Ocean's unique wildlife.
The warning came last month when Antarctic researchers gathered in London to discuss threats to the region's ecology. Concern focused on commercial fishing, and its potential impact on albatrosses, penguins, seals, and whales.
The Circumpolar Sea, what some call the Southern Ocean, has a long history of human over-exploitation. Fur seals, elephant seals, and the great whales were all hunted to the brink of extinction. Now scientists say increased Antarctic krill and fish catches could trigger a catastrophic collapse in the entire marine ecosystem.
The meeting was organized by the British Antarctic Survey (BAS), a UK government-funded organization responsible for scientific research in the region.
BAS Director Chris Ripley said: "Commercial exploitation of [Southern Ocean] fish stocks could result in major and potentially damaging changes."
The BAS provides scientific advice to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Representing over 20 nations, the commission's main role is to balance commercial fishing with conservation in the seas around Antarctica.
"Krill" is Norwegian for "whale food"an apt name for this essential building block for life in the Southern Ocean. Growing to six centimeters (a little more than an inch) long, and often living in dense swarms several miles wide, the shrimp-like crustacean is crucial to many birds and mammals.
John Croxall, principal research scientist at the BAS, said: "For many marine mammals and sea birds, particularly in the South Atlantic sector of the Southern Ocean, krill is by far the most important item of their diet. This is true for minke whale, Antarctic fur seal, Adelie, chinstrap, gentoo and macaroni penguins, black-browed albatross, and white-chinned and cape petrels."
Long-term monitoring by the BAS on South Georgia revealed these species are extremely sensitive to fluctuations in krill numbers. During the 1990s, when krill became less abundant, researchers found that seals, penguins, and albatrosses all struggled to raise their young.
The current Antarctic krill catch is around 120,000 tonnes (132,280 tons) a year, though this figure is well within sustainable levels for a species with an estimated total biomass greater than any multi-cellular animal on Earth, including man.
Scientists say fishing effort has so far been limited by practical problems associated with krill. It contains powerful digestive enzymes that can spoil its flesh after death, while the process of removing its unpalatable shell is relatively costly.
Shifting Fisheries Economics
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