Scientists studying the cormorant colony in Oregon are looking for the best way to remove most of the birds.
Jim Wilson/The New York Times
ASTORIA,
Ore. — The salmon here in the Columbia River, nearly driven to
extinction by hydroelectric dams a quarter century ago, have been
increasing in number — a fact not lost on the birds that like to eat
them. These now flock by the thousands each spring to the river’s mouth,
where the salmon have their young, and gorge at leisure.
As a result, those charged with nursing the salmon back to robust health have a new plan to protect them: shoot the birds.
Joyce
Casey, chief of the environmental resources branch at the Army Corps of
Engineers office in Portland, said that for young salmon headed
seaward, the hungry horde of about 30,000 double-crested cormorants on East Sand Island has posed a risk no less serious than that posed by some of the dams her agency built.
Butch
Smith, a fisherman, said that killing thousands of the birds “is the
one thing out of anything else we can do to recover salmon fastest.”
But
Stan Senner of the National Audubon Society argues that to kill off
some of the cormorant colony here, which makes up one-quarter of the
birds’ western population, “is an extreme measure, totally
inappropriate.”
He said it was possible to shoo them away, noting: “They came from somewhere else. They can go back to somewhere else.”
But efforts to encourage the birds to move have been, at best, inconclusive; the cormorants often return to East Sand Island.
This is not the first time the government has decided to kill a predator or a competitor to protect an endangered species.
Last year the Fish and Wildlife Service began to kill up to 3,900 invasive barred owls,
which outcompete endangered spotted owls. Since 2008, about 60
salmon-eating sea lions have been killed near the Bonneville Dam in the
Columbia River.
In the Great Lakes, the authorities have shot dead thousands of double-crested cormorants over the last several years.
The
wisdom of using lethal means to tinker with the new natural order of
things created by human activities provokes sharp debate.
This
debate is different from ones about killing wolves, coyotes or prairie
dogs to protect livestock. Here, both species, the one to be killed and
the one to be protected, belong in the wild.
“This
is a fascinating issue of how we as a society make choices about how
we’re going to use our resources for the benefit of one interest in
society to the detriment of another,” Ms. Casey said.
This
was true when the Columbia and Snake River dams were built to bring
cheap hydropower to the region; it was to the benefit of growing
communities, but drastically to the detriment of salmon, whose way to
spawning grounds was often impeded by the structures and who were
sometimes killed by the dams’ spinning turbines. Thirteen of 19 salmon
populations in the Columbia River have been listed either as threatened
or endangered.
Ritchie
Graves, a fisheries biologist with the National Oceanic and Atmospheric
Administration, said that the slow improvement in the abundance of
endangered salmon on the Columbia River had helped create the current
predicament.
He
added that the salmon were responding to the agency’s efforts, and the
birds around the region were responding to the improved salmon numbers:
“If you’re a predator in California or southern Oregon and you don’t
have anything to eat, how many years before you move somewhere else?”
For
cormorants around the western United States, “somewhere else” often
turned out to be East Sand Island, on the Washington State side of the
river and close to the spot where the Columbia River meets the Pacific
Ocean.
The
cormorants were not the first fish-eating birds on East Sand Island to
get salmon defenders’ attention. The island, which was significantly
reinforced by dredging activity years ago, also houses thousands of
Caspian terns.
They
moved there 15 years ago — prompted by wildlife officials — from
islands farther up the Columbia River, where salmon were more of their
diet.
Biologists
then reduced the terns’ prime nesting area by two-thirds, to 1.6 acres
after federal officials decided that the terns’ potential to eat
endangered salmon was still too great. Meanwhile, cormorant numbers go
up, even though scientists experimentally reduced the available nesting
area they could use to four acres from 16.
Most
biologists agree that the birds find it hard to beat the ready food
available at the mouth of the river. Last year the total of nesting
pairs of double-crested cormorants rose to nearly 15,000, up from about
6,500 in 1999. Each pair, on average, raises two chicks.
By
2011, scientists at Oregon State University found, the cormorants each
year ate about 20 million juvenile salmon as they headed to sea.
Federal
fisheries officials are focused on 2018, the year that represents the
end of the current, much-litigated federal plan, called a “biological
opinion.” It details the status of endangered salmon stocks, the
specifics of how the government plans to restore them over time, and the
metrics that will determine if they have succeeded.
As
part of the effort to revise this proposal and ensure it passes
judicial muster, scientists have recommended that the corps help the
salmon by cutting the cormorant population by nearly two-thirds, to a
maximum of 5,939 nesting pairs. To do this, the proposed shooting would
begin 2015 and end in 2018, leaving 4,000 dead birds a year.
Blaine Parker, a fisheries biologist for the Columbia River Intertribal Fish Commission, likes the plan.
“To
continue to allow cormorants to grow unchecked is a serious barrier to
salmon recovery,” he said. The tribes, which have treaty rights to the
fish, in 2008 signed 10-year accords with the corps and two other
federal agencies to help salmon restoration.
Mr.
Parker argues that the government and rate payers who buy
hydroelectricity “have spent hundreds of millions annually to make the
ecosystem more fish-friendly” and do not want to see the fish eaten by
birds.
But
Mr. Senner of the National Audubon Society said some of the scientific
analysis in the corps’ proposal was insufficient. “We’re not persuaded
they have fully explored ways of improving habitats elsewhere or other
means of dispersing” the cormorants, he said.
Bob
Heess, a retired marine biologist, came late last month to an open
house in Astoria during which the corps had conversations with the
public and took comments on their plan to shoot birds.
His view: “I’ve seen people try to mess with Mother Nature before, and it never works. It goes toward creating more problems.”
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