Earlier this year, the agency approved a controversial plan to shoot around 11,000 double-crested cormorants to protect threatened and endangered fish. Studies show the birds eat up to 20 percent of young salmon and steelhead as they swim down the river to the ocean.
But documents distributed Wednesday to news media show the agency’s own analysis concluded those fish would die in the ocean anyway before they returned to the river to spawn as adults. Thus, the analysis found, killing cormorants would have no effect on the overall survival of protected fish.
Bob Sallinger, conservation director of the Audubon Society of Portland, said he recently received the documents through a court order tied to his group’s lawsuit against the cormorant management plan. He called the findings “explosive.”
“In other words, if the cormorants did not eat those salmon something else would,” he said. “It tells us the federal government is killing protected wild birds for absolutely no reason.”
An official with the U.S. Fish and Wildlife Service said the agency would not comment because the report is related to ongoing litigation.
The analysis looks specifically at whether cormorant predation is an additional source of mortality for Snake River steelhead or if other sources of mortality would end up killing the same number of fish. Studies have shown Snake River steelhead suffer the most predation from cormorants among protected fish species in the Columbia. The analysis concludes there is no evidence that the cormorant predation is an additional source of mortality for steelhead. It goes on to say that those findings indicate killing cormorants isn’t likely to benefit other species of fish either.
“As a consequence, efforts to reduce cormorant predation on steelhead (e.g., culling) are expected to have no effect on Snake River steelhead population productivity or adult abundance,” the document states. “Since Snake River steelhead were most likely to benefit from reductions in cormorant-induced mortality but showed none, benefits to other species are also unlikely.”
The National Oceanic and Atmospheric Administration has studied this issues raised by this report while developing a plan for salmon and steelhead survival through the Columbia and Snake rivers’ hydroelectric dams, said spokesman Michael Milstein.
He said NOAA did not agree with the conclusion that even if they’d managed to get past the colony of hungry cormorants, the ocean-bound juvenile fish would have perished before making their way back to the Columbia River.
“We just don’t agree with that approach. We know 1.5 to 2 million smolts are getting eaten, and we don’t believe all of them would have died in the ocean,” Milstein said.
The double-crested cormorant colony at the mouth of the Columbia River has grown from around 100 pairs on East Sand Island in 1989 to 14,916 nesting pairs in 2013. That makes it the largest breeding colony of cormorants in North America.
The Corps says it needs to wipe out about half the cormorant population by 2018 to satisfy requirements by the National Marine Fisheries Service to protect fish runs that also suffer impacts from hydroelectric dams on the Columbia River.
Corps research has found that alternatives to lethal removal such as shrinking the birds’ habitat hasn’t had an effect on the number of birds nesting on the island.
The Corps’ plan for reducing the population of cormorants involves shooting adult birds and killing around 15,000 unborn chicks through a technique known as egg oiling – spraying vegetable oil on eggs to block the intake of oxygen so the chicks never hatch.
So far this year, the Corps has killed 158 adult cormorants by shooting them with rifles, and it has oiled around 5,000 unhatched eggs.