Federal scientists are finding young salmon in Northwest estuaries and hatcheries contaminated with toxic compounds. In some areas, including the lower Columbia River and some Oregon hatcheries, the levels are high enough to harm fish health.
The National Marine Fisheries Service, during three years of targeted testing, found industrial compounds called polychlorinated biphenyls, or PCBs, as well as the banned pesticide DDT in juvenile salmon plucked from Northwest estuaries and hatcheries.
Scientists say they aren't surprised salmon carry some of these now-banned compounds, which were used extensively until the 1970s and persist in the environment for years.
But they are surprised that PCB levels are high enough to harm fish immune systems. And they don't know where the pollutants are coming from.
"We need to be cautious," said Tracy Collier, manager of the ecotoxicology program at the National Marine Fisheries Service. "We're close to the threshold where effects may begin to occur."
More studies need to be done to determine whether the young salmon carry the contaminants through adulthood at levels that threaten humans who eat them.
Some of the highest PCB levels were found in fish near the mouth of the Columbia River and in several Oregon hatcheries. This raises questions about hatchery management and whether dredging the Columbia River navigation channel will make matters worse. Scientists think the river's large estuary near its mouth could be key to restoring declining salmon stocks.
U.S. Fish & Wildlife Service officials also worry that the contaminants are being passed on to wildlife that feed on Columbia River salmon, including cormorants, bald eagles and Caspian terns. All have been found to have elevated levels of toxic compounds.
Scientists said the contamination could come from anywhere in the vast Columbia River system, including areas of past and present industrial pollution, runoff from cities and farms and fish feed used in hatcheries.
"They're going to have to look harder at the origin of those fish in order to answer those questions," said Larry Curtis, head of Oregon State University's Department of Environmental and Molecular Toxicology.
The National Marine Fisheries Service presented the findings in June to an independent panel of scientists, including Curtis, that was mediating an impasse between the fisheries service and the U.S. Army Corps of Engineers. The two agencies are trying to reach agreement about the environmental impacts of deepening the Columbia River.
Scientists say they doubt the findings will stop the proposed project. But fisheries service officials, who must approve the deepening, are still negotiating with the Corps about monitoring contaminant levels should the project go forward.
The National Marine Fisheries Service, charged under the Endangered Species Act with protecting threatened salmon, began systematically testing hatchery and wild juveniles for contaminants in 1998.
Tissue tests found PCB levels of 5 to 70 parts per billion. Salmon begin to show health impacts with PCB levels of 24 to 72 parts per billion, the fisheries service says.
The highest concentrations -- more than 50 parts per billion -- were found in fish from the Duwamish Estuary near Seattle; around Sand Island near the mouth of the Columbia River; in Yaquina Bay in Newport; and in the Salmon River, Alsea, Butte Falls and Cole M River hatcheries in Oregon.
DDT levels above 40 parts per billion were found in juvenile salmon from the Salmon River Fish Hatchery in Otis and around Sand Island in the Columbia River. Scientists aren't yet sure whether the DDT concentrations pose dangers as well.
PCBs and DDT were also found in stomach contents of juvenile salmon from the mouth of the Columbia River, suggesting that young fish had eaten contaminated food in the nearby estuary, Collier said.
Jeremy Buck, environmental contaminant specialist with the U.S. Fish & Wildlife Service, said the findings support his belief that contaminants are being transferred and magnified as they pass up the food chain among animals that prey on salmon.
PCB and DDT-byproduct levels in bald eagles and cormorants are high enough to cause reproduction problems, Buck said. And studies show bald eagles nesting along the first 60 miles of the Columbia River produce half as many young as other eagles in Washington and Oregon.
But scientists have been unable to find the source of the contaminants. Tests show Columbia River sediments -- a likely source -- are relatively clean.
National Marine Fisheries Service officials believe hatchery salmon could be picking up contaminants from commercial fish feed. In July, they tested four brands of commercial food and found PCB and DDT in all of them.
Previous studies also have found toxic chemicals in fish feed. A 1997 study of trout and salmon feed produced in Northern Europe detected chlordane, a toxic insecticide.
A 1998 study of catfish feed made in Arkansas found elevated levels of dioxins, which are highly toxic to aquatic life.
The contaminants likely come from fish meal and fish oil.
"These oils are where a lot of these long-term contaminants are going to accumulate," said Keith Cooper, professor of toxicology at Rutgers University and co-author of the catfish study.
Researchers discovered the problem in the late 1980s when fish raised for laboratory experiments began turning up contaminated. Many researchers stopped using commercial fish food entirely, Cooper said.
Oregon State University's Core Facility for Marine and Freshwater Biomedical Center mixes its own feed, using milk protein, vitamin E, a mineral mix and fish oil that has been stripped of contaminants, Curtis said.
Jim Myron, conservation director with Oregon Trout, said the National Marine Fisheries Service findings suggest that toxic pollutants could be playing a greater role in the decline of salmon species than thought. He also lamented the contamination of hatchery fish feed.
"We're investing millions and millions of dollars a year in the Columbia Basin on hatchery fish production," Myron said. "If we're poisoning them in the process, what sense does that make?"
A fish health specialist with the Oregon Department of Fish and Wildlife, which operates 34 hatcheries in the state, said he would explore the costs of doing more tests on hatchery fish.
"It bears some following up on," Richard Holt said. "It's more (contamination) than you'd like to see."