Whale Haunt: Nursing, feeding spot found off south Chile

A systematic survey has discovered a hangout for blue whales in the Gulf of Corcovado, an inlet of the Pacific Ocean between the southern Chilean mainland and the largest of the Chilean Islands. Last year, 47 blue whale groups, some including mothers and youngsters, were sighted in that area.

In the first 60 years of the 20th century, commercial whaling wiped out 97 percent of the Southern Hemisphere’s blue whales, note Rodrigo Hucke-Gaete of the Southern University of Chile in Valdivia and his survey team. As of 2000, the International Whaling Commission (IWC) estimated that 700 to 1,400 blue whales remain in the Southern Hemisphere. Observations that can be made at the new, midlatitude site should fill in some knowledge gaps and help refine conservation efforts, Hucke-Gaete and his colleagues say in an upcoming Proceedings of the Royal Society of London B: Biology Letters.

“It’s an exciting discovery,” says another blue whale researcher, Bruce Mate of Oregon State University in Newport. Usually, blue whales are sighted near the poles or at the equator. In the Northern Hemisphere, scientists have found some blue whales that frequent midlatitude spots. But in the Southern Hemisphere, a midlatitude location was “unexpected,” says Mate.

Whaling records from 1907 and 1909 describe abundant blue whales in the area. An IWC survey in the late 1990s turned up a modest number of blue whales along the Chilean coast. But when several members of that survey team subsequently went on a sightseeing cruise in the area, they saw more blue whales than they had observed during months of official whale counting, says Mate.

Following up those serendipitous sightings, the new project systematically searched the Gulf of Corcovado region with five plane flights and two boat trips during the austral summer months of January to April 2003. Overall, the team made 153 sightings of blue whales, including 11 mother-calf pairs. The researchers’ technique didn’t always identify individual whales, so some were probably counted more than once.

On the basis of the behaviors that the researchers observed and the young ages of the calves, Hucke-Gaete and his colleagues classified the area as a feeding and nursing site. Mate cautions that neither the recently recognized area nor any other spot on the globe has been definitely shown to be a blue whale calving ground. The young whales stay with their mothers for about a year.

Mate adds that although the new population isn’t large, its genetics may differ from that of whales observed at Antarctica.

Blue whales are protected from outright hunting worldwide, but accidental boat collisions and other clashes with people take their toll. Mate says that he hopes the Chilean government will find ways to make the newly recognized feeding grounds a safe haven for blue whales.

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