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Scientists Adopt New Plan to Move Whales

May 19, 2007

WEST SACRAMENTO, Calif. — Marine scientists trying to lure two injured whales out of a river prepared Friday for Plan B: Herding the animals by boat while banging pipes underwater.

In the meantime, a marine mammal rescue crew aboard a Coast Guard cutter stuck with the original strategy of playing recorded sounds of other humpbacks feeding.

The mother whale and calf are stranded at the Port of Sacramento, having hit a dead-end after traveling 90 miles through San Francisco Bay and up the Sacramento River. Their cuts were apparently caused by a boat propeller.

The herding and banging technique would be applied on Tuesday only if the more numerous and varied whale sounds planned for Friday fail and the twosome do not start swimming toward the Pacific Ocean on their own over the weekend, said Frances Gulland, director of veterinary science at the Sausalito-based Marine Mammal Center.

“We really do not want to stress the mother or calf in any way because they are compromised by the injuries,” Gulland said.

On Thursday, the whales twice began moving out of the port after the feeding sounds were broadcast from a boat. But both times they turned back into the large basin where oceangoing freighters turn around.

Biologists hope to get the whales back into the ocean, where food is more plentiful and the saltwater can heal their cuts. Recorded whale sounds worked in 1985 with a humpback nicknamed Humphrey, which swam in the delta for nearly a month before returning to the Pacific.

But the situation near Sacramento was more complicated, they said. It involves a mother and calf, rather than a single whale, and the mother’s concern for her baby may explain why she did not respond to the scientists’ efforts to appeal to her stomach, Gulland said.

The pair also are much farther into the Sacramento-San Joaquin Delta than Humphrey was. The injuries add another dimension, as scientists say they do not know how the wounds might affect the whales’ behavior. The larger whale had a gash 2 feet long and 6 inches deep, filled with blubber. The calf’s wound was difficult to assess because it is on the animal’s underside, below the water line.

“It’s not like we’re applying something we have a lot of experience with in the past. It’s essentially an experiment,” said Pieter Folkens, an Alaska Whale Foundation biologist.

The failure of Thursday’s attempt also may be related to the recordings used. They were of Alaskan whales that might be part of a different pod than that of this mother and calf.

“It’s kind of like speaking Chinese to somebody from Boston, but at least you recognize that it might be another member of the same species,” Folkens said.

The good news on Friday was that biologists did not detect significant health changes from a day earlier, Gulland said.

“Both mother and calf are still swimming and breathing and surfacing at similar rates as they were over the past few days,” she said.

Even if the recordings eventually work, scientists said luring the whales back to the bay could take days to weeks.

On the Net:

Marine Mammal Center: http://www.tmmc.org/learning/comm/humpbacks_delta.asp




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