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The world's oceans are already in a warming trend that could alter fish stocks, perhaps damaging coral reefs that are vital nurseries for tropical species while boosting northern stocks of cod or herring. "The global oceans have been warming since the middle 1970s and several studies have shown that the warming can be attributed to a human-produced signal," said James Hurrell of the US National Centre for Atmospheric Research.
Off New York this week, rescuers guided eight dolphins into open water after they became stranded in a shallow cove, apparently because unusually warm waters meant fish on which they feed were staying closer to the coast. A type of Black Sea jellyfish seems to have become established off Scandinavia, perhaps flushed out of the ballast tanks of visiting ships and now able to survive because of less chilly waters in winter.
Norway's Institute of Marine Research said 18 tropical swordfish had been seen off Norway since 1967 and sightings were becoming more frequent. Four were spotted in 2006 alone, including a 22kg specimen caught on November 14. "There have been many record high temperatures in recent months," said Jan Aure, a researcher at the Institute. "The climate regimes are changing and moving northwards." In Lista by the North Sea, for example, water temperatures were a record 8.5C, 2-3 degrees above normal for January.
In recent years, salmon have been seen swimming north of the Bering Straits between Russia and Alaska, and jellyfish plagued Mediterranean beaches in 2006. Over-fishing and destruction of habitats is also disrupting marine life.
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http://www.theaustralian.news.com.au/story/0,20867,21089133-1702,00.html