Killer Whales Snack on Seals, Save Salmonby Reuters
Environmental News Network, March 5, 2003
SEATTLE -- Endangered Seattle salmon are breathing more easily after a traveling troupe of killer whales took a big bite out of the area's harbor seal population during a two-month feeding binge, wildlife experts say.
Distraught seals huddling on shore in Hood Canal near Bremerton, Wash., are safe to go back in the water, though perhaps half of their friends will not be there, having been chomped down by 13 whales, who have finally left town.
"At the end of last week the seals were up on the bank quivering," said Steve Jeffries, a marine mammal biologist at the Washington State Department of Fish and Wildlife. "This was a perfect place to be a killer whale; probably a bad spot if you happened to be a harbor seal."
The killer whales, or orcas, were likely drawn by the ample supply of some 1,500 Hood Canal seals, growing as large as 250 pounds on a steady diet of 200 salmon a day.
The seals added to the strain on local salmon runs already depleted by pollution, habitat loss, fishing, and hydroelectric dams interrupting their lengthy river migrations.
The visiting transient whales, which can grow to as large as 10 tons, have thinned out the herd, giving salmon a better chance to get past the voracious seals when they leave the ocean and head back upstream to spawn in the fall.
"It will probably benefit salmon runs in the short term, and in the long run we expect the seal population to recover. This is probably just a natural cycle," Jeffries said, adding that the seal population in surrounding waters is about 30,000, up from 7,000 or so 30 years ago.
The striking black-and-white orcas are a cousin of the popular resident whales, who eat salmon in the waters off the Pacific Coast from Washington to Alaska. They too have declined in numbers in recent years.
Transient orcas eat mammals like gray whale calves and California sea lions and even some birds. The visitors will likely head north next, except for one orca who typically migrates southward to California, Jeffries said.
"From everything we can tell, they were just in there doing their normal, transient foraging behavior," he added.
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