Group says breaching dams would provide more food for threatened Puget Sound orcas
Another group is taking aim at the lower Snake River dams, this time as a vehicle to recover southern resident killer whales that spend much of the year in Washington’s Puget Sound.
Members of the Southern Resident Killer Whale Chinook Salmon Initiative are pushing a petition that calls for breaching the dams, something that salmon advocates have long desired.
According to the petition posted on change.org, “chinook salmon runs originating in the Columbia/Snake River watershed are the singular most important food source for the killer whales’ survival.”
Most fisheries scientists agree breaching the dams would greatly benefit threatened and endangered Snake River salmon and steelhead. But the federal government chose instead to invest in fish passage improvements at the dams and a mix of habitat restoration, hatchery reform and tighter management of sport and commercial fishing.
The Puget Sound population of killer whales, also known as orcas, face three distinct threats: a shortage of prey, the accumulation of toxic chemicals in their bodies and interference from boat traffic and noise. All of the threats are intertwined, said Lynne Barre, a marine biologist with the protective resources division of the National Oceanic and Atmospheric Administration Fisheries in Seattle.
When whales don’t have enough to eat, they rely on the fat reserves in their blubber. But that is the same place toxic chemicals are stored like the now banned insecticide DDT, PCBs found in industrial coolants and lubricants and PBDEs found in flame retardants. Whales acquire the toxins as they eat fish, that in turn acquire the chemicals when they feed on other fish and organisms lower in the food chain.
When those fat reserves are tapped because of food shortages, the chemicals enter the blood stream of the whales and can make them ill. Whales that are suffering from toxins have a more difficult time feeding.
Noise and interference from recreational, commercial and military crafts can also change the feeding behavior of the whales and make them malnourished.
“The three main threats are probably working together to cause the problem,” Barre said.
Those pushing the breaching initiative say removing the dams would dramatically boost Snake River spring chinook and doing that would provide more food for killer whales, which would go a long way to addressing all three threats.
“The southern resident killer whales are starving,” said Sharon Grace of Friday Harbor and coordinator for the Southern Killer Whale Chinook Salmon Initiative.
Scientists have established the whales are often in poor shape from lack of food. During the summer months when they frequent the Puget Sound area and seas around the San Juan Islands and Vancouver Island, they feed primarily on chinook from the Fraser River in Canada.
During the winter months, they travel up and down the West Coast between British Columbia and California where scientists believe they also feed on chinook. But they don’t have good information on which stocks of chinook the whales target or how important fish from the Snake and Columbia rivers are to the whales.
Brad Hanson, a marine biologist with NOAA Fisheries, is working to learn more about the diet of killer whales when they spend time off the West Coast, or what he calls the outer coast. He is currently on a research ship following the whales off the coast of Oregon and Washington and picking up both remnants of salmon the whales feed on and fecal samples. By analyzing the DNA from the samples, the research team can determine the origin of the salmon.
Earlier this week the whales were near the mouth of the Columbia and Hanson responded to questions via email from his ship.
“Based on information about where portions of the population spend their time on the outer coast, limited prey sampling, and the relatively high abundance of Columbia River chinook salmon, it is likely that the Columbia River salmon are an important food source for the southern resident killer whales. Exactly how important, however, is not yet known.”
Increasing chinook abundance off the coast is likely to benefit the whales. But scientists, Hanson said, don’t yet know the degree to which rising salmon numbers will benefit whales. That is because many other predators like seals and sea lions also feed on chinook.
“The benefits from increases in salmon may therefore be distributed across many other salmon predators, with only marginal specific returns to the southern resident population,” he said. “Investigating which salmon recovery actions will have the greatest specific benefit to southern resident killer whales is a high priority area for future research.”
Deborah A. Giles, science adviser for the Southern Resident Killer Whale Chinook Salmon Initiative, is certain whales would have no trouble exploiting an increase in Snake River chinook abundance that would follow dam breaching.
“They are highly efficient predators,” she said. “The fact that there is more fish out there means there is more fish for the whales. They can fend for themselves. They are apex predators.”
Giles is also confident that the work Hanson and others are doing will close the data gaps regarding the importance of Snake River salmon to orcas.
“I think ultimately that is exactly what the data is going to show, there is no doubt in my mind,” she said. “I don’t think there is doubt in anybody’s mind. It’s clear to everyone who researches these guys that the Columbia River chinook are very, very important and knowing what the runs in the Snake River used to be, it’s almost by default that it has to be an important river.”
Grace said the group has collected about 10,500 signatures on the petition and plans on collecting many more before presenting it to members of Congress and President Barack Obama.
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