A final cormorant management plan released by the U.S. Army Corps of Engineers Friday calls for the killing of around 26,000 birds to protect threatened and endangered salmon and steelhead.
The agency's preferred plan would involve shooting around 11,000 double-crested cormorants nesting on East Sand Island in the Columbia River. That plan also includes 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.
It's a change from a draft plan released last year calling for the killing of around 16,000 birds primarily by shooting them with shotguns; the new plan reduces the number of birds that would be shot and increases killing through egg oiling.
Officials say it’s the best way to reduce the colony as required under an agreement that allows the Corps to operate dams on the Columbia River. The Corps 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 dams.
Scientists estimate cormorants on East Sand Island ate 18 million protected salmon and steelhead in 2013 and are regularly consuming 10 percent to 15 percent of the populations swimming through the Columbia River estuary.
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, said Joyce Casey, environmental resources branch planning chief for the agency.
East Sand Island's double-crested cormorant colony has grown from around 100 pairs in 1989 to 14,916 nesting pairs in 2013. That makes it the largest breeding colony of cormorants in North America.
Casey said increasing egg oiling allows the agency to reduce the number of birds it would have to shoot to control the population.
"In essence, we are not allowing individuals to be born into the population instead of having to shoot them," she said.
The Corps’ environmental review found the proposed actions wouldn’t jeopardize the cormorant population as a whole.
Columbia River Indian tribes have expressed support for killing cormorants to protect salmon and steelhead. In a statement released Friday, the Columbia River Intertribal Fish Commission supported the Corps' new plan as an essential step to reduce fish losses, but suggested it might not go far enough.
"Avian predation upon Columbia River salmon stocks has grown to become the single-largest, unchecked impact on their sustainability," said Commission Executive Director Paul Lumley. "While this management action is warranted, it may not be enough to reduce the staggering fish losses."
Bird advocates have voiced opposition to the plan. The corps received more than 150,000 comments on its draft plan and estimates about 149,000 of them came from two opposition campaigns from Care2 and the Audubon Society.
Bob Sallinger of the Portland Audubon Society said he's disappointed in the final version of the plan. After the draft was released last year, he said killing so many birds was unacceptable – especially because many of the fish the birds are eating are not wild fish but have been reared in hatcheries.
"As far as we're concerned the issues we've been raising over the past years have not been resolved or answered adequately," he said of the final plan. "We believe this control action should not go forward."