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Blue whales - under threat reveals that, as a result of rising temperatures, the sea ice surrounding Antarctica is beginning to disappear. This threatens the population of krill, the tiny crustaceans that make up the bulk of the blue whale's diet. Krill depend upon microscopic plants known as marine algae, which are released into the ocean during the summer. As the ice diminishes, fewer algae will be released in the warmer months, providing fewer feeding opportunities for young krill and seriously affecting the entire ecosystem of the Southern Ocean.

A 2001 study published by the Royal Society analysed data on krill-eating predators at South Georgia from 1980 to 2000 and found that population size and reproductive performance were declining in all species. Its authors concluded that "the biomas of krill... was sufficient to support predator demand in the 1980s, but not in the 1990s" and that "the demand for krill exceeds supply."

Stuart Chapman, WWF's whale specialist, said: "The world's largest problem could mean extinction in the Antarctic for the world's largest animal. The Blue whale population in the Antarctic was drastically reduced by commercial whaling - from 250,000 a century ago to probably below 1,000 today. The population has shown no signs of recovery since the species was officially protected from whaling more than 35 year ago."

Despite the ban on hunting blue whales introduced in 1965, Soviet factory ships continued to kill them into the 1970s. In 1994 it came to light that the Soviets had falsified their records, reporting a catch of just 156, when 1,433 blue whales had been killed. Since then, there is no evidence that their numbers have started to recover, and any slight impact on the remaining population could mean extinction in the Southern Ocean.

To add to the problems, several countries are showing an interest in stepping up their commercial krill fishing operations, possibly to unsustainable levels. Stuart Chapman, said: "It would be a catastrophe for the natural world if the decline of the blue whale was accelerated by new commercial pressures. This activity could be the final nail in the coffin of the blue whale."

With less than a week to go before the opening of the International Whaling Commission meeting in London, WWF is calling on the IWC to provide funding for long-term population surveys and to undertake research on the links between blue whales, krill and climate change.
Read the report
Blue whales - under threat is available to download as a pdf file. To read files of this type, you will need the Adobe Acrobat Reader, which is available free of charge from the Adobe website.

Further information
To find out more about whales and the threats they face, visit the WWF target:_blank website.

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