Orca Numbers Down in Puget Sound
Commercial salmon fishing remains a threat to killer whales
Roger Di Silvestro
AN ONGOING SURVEY of killer whales, or orcas, in Puget Sound has reported the loss of seven of the animals in what could be the biggest decline in 10 years (for details on the Puget Sound whales, see “Orcas on the Edge”). The sound is home to three orca pods now totaling 83 animals; each pod lost at least one member.
The seven animals include one female that was a great-great-grandmother and two babies that vanished the week they were born. Loss of these animals could be chalked up to natural mortality, says Ken Balcomb, a senior scientist with the Center for Whale Research on San Juan Island. The older animal was nearing maximum life span, and about half of orca young die as babies. “For the others, they were all in their prime,” Balcomb says. “We had only one that was even close to the average life span.” The loss of two females of breeding age was especially serious, Balcomb says, because their deaths reduce the sound’s breeding females to only 10 individuals.
It’s the Fishing
Balcomb blames the decline on a dwindling supply of chinook salmon, which studies show account for 80 percent of the diet for Puget Sound’s killer whales. About half of the historic salmon stocks coming out of local rivers are extinct, and surviving stocks have declined by about 10 percent in recent decades. Individual salmon stocks are listed as endangered or threatened, but the fish continue to be taken by a sportfishing industry that accounts for $500 million yearly in license fees alone in British Columbia. The fish also are captured as bycatch in commercial fishing nets. Although measures are taken to reduce the catch of listed stocks in U.S. waters, these measures are not effective enough, Balcomb says, because anglers cannot readily identify and release fish from listed stocks, as required by law. Off Canadian waters, the fish can still be legally taken. “My solution to the orca problem,” says Balcomb, “is to stop all fishing.”
The Puget Sound orca survey is scheduled for completion in December 2009.