The calls of Orca whales in the Pacific are getting longer, so they can be heard by other whales over the noise of heavy boat traffic. Orcas only do this when engine noise reaches a critical level.

Paul Rincon writes in bbcnews.com that ironically, much of the boat noise that bothers them comes from whale-watching tourists. No difference was found in the length of their calls over the 1977-81 and 1989-92 period, but there was a 10-15% increase in the length of calls made by the Orcas during the 2001-03 period. Their numbers have dropped, so they also have to make their calls longer in order to reach each other. Background noise could eventually be the end of them, since they need to communicate and cooperate in order to find food.
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Dead whales have been turning up on the beaches in Maine. Some of them are rarely seen in this area, and no one can figure out what killed them. Now scientists think sonar is giving whales the same kind of “bends” that deep sea divers get.

“The only way we can explain these findings is that it is a condition very similar to decompression sickness in humans,” says marine specialist Paul Jepson. “Sonar may cause a disease like the bends.” Underwater sonar is used by the military to detect submarines. Patricia Reaney writes that researchers have found bubbles in the tissue of stranded whales and dolphins that are similar to the effects of decompression sickness (DCS) in humans.
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Over a quarter of all deaths of adult beluga whales in Canada?s Saint Lawrence Estuary are caused by cancer, researchers have found. Such high rates of cancer are unprecedented in wild animals, except for fish. Industrial pollution is the most likely cause.

Belugas live entirely in the Arctic and sub-Arctic. There are approximately 70,000 worldwide and about 650 of these live in a small region of the St. Lawrence Estuary in Quebec. Between 1983 and 1999, 263 dead whales were reported. Daniel Martineau of the University of Montreal and his team conducted 100 autopsies of the whales and found that cancer, particularly cancer of the digestive tract, was the cause of death of 18 per cent of juvenile belugas and 27 per cent of the adults.
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