As the federal government inches toward listing Puget Sound's orca whales for protection under the Endangered Species Act, University of Washington researchers have launched a multiyear effort to determine the cause of the marine mammals' plummeting population.
Every morning since June, researchers led by doctoral student Stefanie Hawks-Johnson have joined hundreds of people who board commercial whale-watching boats in Washington and British Columbia in hopes of spotting the black-and-white whales.
Working aboard the Saint Nicholas, a tour boat operated by the Mosquito Fleet out of the Everett Marina, the researchers are collecting data about the orcas' behavior. They are using such novel tools as a small radio-controlled catamaran that can approach within 100 yards of the whales and a fish finder that can show what the animals are feeding on up to a quarter of a mile beneath the ocean surface.
Scientists believe that the whales are declining because of a drop in salmon runs and increasing contamination from polychlorinated biphenyls (PCB's) that are accumulating in their blubber. Since 1996, the size of the southern resident community - the name for Puget Sound's orcas - has tumbled from 97 to 78 animals in the three pods or groups of whales that inhabit local waters.
Most of the animals being lost are young whales of reproductive age. Some people have speculated that the growing number of commercial whale-watching boats also may be effecting the orcas and their behavior. "The orcas are getting hit with a triple whammy," explained Hawks-Johnson. "We believe that there simply are not enough salmon for them and we think the whales may be going after a different kind of prey, bottom fish.
That calls for a greater energy requirement by having to dive deeper to forage. And bottom fish are likely to be more toxic than salmon with pollutants such as PCBs."
The typical orca can eat between 100 and 300 pounds of food a day, and oil-rich sa
Contact: Joel Schwarz
University of Washington