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NMFS Issues Technical Report on Caspian Terns

by Barry Espenson
Columbia Basin Bulletin - May 31, 2002

A draft report now out for technical review likens the impact of predatory Caspian terns on migrating Columbia Basin juvenile salmon and steelhead to those brought by human activities that increase fish mortality.

"Caspian tern predation on juvenile salmonids significantly affects recovery, however removing all tern predation will not, by itself, lead to full recovery of any listed salmon and steelhead stock," says the document released late last month by the National Marine Fisheries Service study.

"The evaluation of "Caspian tern predation on Salmon and Steelhead Smolts in the Columbia River Estuary" is one of three reports called for in the settlement of a lawsuit that pitted bird advocates vs. salmon advocates.

Those three necessary technical reports include:

  1. Avian predation analysis to determine levels of predation that do not impede salmon recovery;
  2. Status Assessment of Caspian Terns; and
  3. Feasibility study of potential Caspian Tern nesting sites in the Pacific Northwest.
The first two are now out in draft form. The third is not yet complete.

A successful lawsuit filed by the National Audubon Society, Defenders of Wildlife, Seattle Audubon Society and the American Bird Conservancy threatened to halt a plan relocate what is considered the world's largest Caspian tern colony. The goal was to shift the birds from their favored site, Rice Island, to a locale at the river's mouth, East Sand Island, where they would consume fewer juvenile salmon and steelhead and more marine fishes.

The plan shifted most of the birds in 2000 and all of the birds nested at East Sand in 2001, reducing smolt consumption from and estimated 11.7 million in 1999 to 7.3 million and 5.9 million respectively in 2000 and 2001.

The plaintiffs in the lawsuit argued vehemently that Caspian terns are being scapegoated for the demise of salmon. The fish-eating birds are a natural part of the ecosystem, the bird conservation groups say. The federal Columbia-snake hydrosystem and other human uses that alter salmon's freshwater habitat are more the culprits, according to the plaintiffs.

U.S. District Court Judge Barbara Rothstein agreed in large part. In an August 2001 injunction imposed Rothstein prohibited any harassment of the birds in the estuary or manipulation of habitat and threatened implementation of the management plan this year. The defendants, the U.S. Army Corps and U.S. Fish and Wildlife Service had appealed the decision to the Ninth Circuit Court of Appeals, which steered the two sides toward settlement negotiations. The Corps is in charge of the dredging. The USFWS has responsibility to protect the migratory birds that fly north to nest and rear their young during the late spring and summer.

Rothstein ruled that the Corps and USFWS acted illegally when they initiated a plan to turn the world's largest colony of Caspian terns away from their preferred nesting site without the benefit of a full environmental impact statement.

The draft report is more of the same, according to Gerald Winegrad, vice president for policy for American Bird Conservancy.

The NMFS document is "woefully inadequate and poor science," Winegrad said. He said the calculations continue to exaggerate the impact the tern predation has on wild, listed fish. Winegrad called the birds' impact -- as measured in smolt-to-adult returns, miniscule compared to the impacts of hydrosystem, the destruction of habitat, harvests and other man-caused factors.

"There is no direct correlation that has even been scientifically shown between the Caspian tern predation and the adult return," he said.

The plaintiffs in the case have commissioned several experts in prey-predator relationships to comment on the draft documents. Comments are due by July 1.

Those comments and the comments of others will be considered, and the documents revised with final reports due at the end of August, according to Tara Zimmerman of the USFWS.

"They will become a part of the information base we use to develop alternatives and select where we want to go from here," Zimmerman said. The settlement agreement calls for the development of a final environmental impact statement that outlines a long-term management plan with protections for the terns.

The life cycle model developed at NMFS' Northwest Fishery Science Center -- the Cumulative Risk Initiative -- was used to estimate impacts of the tern predation on the "population growth rate" of listed Columbia Basin stocks. The model estimates that, if the predation were eliminated it would yield a maximum potential improvement in population growth rate of from 0.2 to 2.3 percent. A 50 percent reduction in predation is estimated to produce a 0.1 to 1 percent improvement.

"For comparative purposes, changes called for in NMFS' Biological Opinion on operation of the hydropower system (FCRPS), to improve passage for both adults and juveniles are anticipated to increase population growth rates by approximately 1-2 percent for the Snake River spring/summer chinook salmon ESU and nearly 5 percent for the Snake River fall-run chinook salmon ESU (NMFS 2000)," the report says.

The NMFS draft report also says, in summary:

The draft "Status Assessment and Conservation Recommendations for the Caspian Tern (Sterna Caspia) in North America" was released on April 25. Authors of the preliminary document were W. David Shuford of the Point Reyes Bird Observatory in Stinson Beach, Calif., and David P. Craig of Willamette University's department of biology.

Tern populations, for the most part, have increased across much of the nation, according to the report. The Caspian tern "still occupies most of its former range and has expanded slightly into new areas."

"Continent-wide population increases were fueled initially be the reduction of elimination of some historical pressures (e.g. hunting for the millinery trade) but more recently by changed in breeding habitat and prey resources," the draft says. "In coastal areas, increases are strongly associated with use of artificial habitat for nesting."

That boon may also be a bane in places such as the Columbia River estuary. Islands created from navigation channel dredging spoils became havens for terns. The NMFS report says that no terns had been nesting in the estuary prior to 1984, when 1,000 pairs settled onto newly formed East Sand Island. The birds had "apparently moved from Willapa Bay" to the north of the estuary.

The colony moved upriver to Rice Island in 1987 and grew to an estimated 10,000 pairs. The management plan in place for the past two years resulted in the birds being relocated back to East Sand.

The draft tern report points out that the Columbia estuary tern colony now represents two-thirds of the Pacific Coast population and one-quarter of the North American population. That bunching of the population at one site leaves it "more vulnerable to stochastic events such as disease outbreaks, severe storms, disruption by predators or human disturbance and oil spills."

Winegrad said that the tern population draft report "seems to be a scholarly and a fair and accurate assessment." He noted that the report cites data indicating that the Columbia estuary population appears to have leveled off, or be in decline, over the past two years. The terns, Winegrad said, have been essentially shoehorned onto the only habitat available to them. Historic inland habitat, and along the Washington coast, has been destroyed.

"The terns just don't have any place to turn to," he said. He faulted state and federal officials for repeating a goal of finding alternative habitat for the terns but failing to come up with any.

"It's been four years and they still don't have a square inch" of new habitat," Winegrad said. "It's more political than it is biological." He said the exaggerated impact of tern predation on salmon has made the pursuit of alternative habitat more difficult. Local and tribal entities have headed off attempts to establish habitat along the Washington coast.

The draft tern population assessment urges conservation efforts on "multiple fronts:"

As part of the peer review process, copies of draft reports were provided to a list of scientists chosen by the plaintiffs in the case. The National Audubon Society, Defenders of Wildlife, Seattle Audubon Society and American Bird Conservancy filed the lawsuit early in 2000 challenging the scientific basis for the plan and the agencies' failure to complete an adequate environmental impact study. The groups said the tern management developed by the federal, state and tribal entities did not take into account the long-term welfare of the birds.

The agreement stipulates that the reviewers had no less than 60 days to submit written comments on the draft reports, which would be submitted individually by each reviewer and considered by the defendants before finalizing the reports.

The settlement agreement charges the USFWS, in cooperation with NMFS and the Corps, with initiating National Environmental Policy Act scoping in April 2003 on Caspian tern management in the Columbia River estuary through publication of a notice in the Federal Register.

A draft environmental impact statement is to be completed and published by Oct. 1, 2004, and the final EIS and record of decision must be completed and published by Feb 28, 2005. The USFWS must initiate implementation of the alternative selected in the ROD by March 2005.

"In addition to those issues required to be considered, discussed, and evaluated under NEPA, the EIS shall include: (1) an evaluation of a no-action alternative (no management) wherein the biological necessity for any management will be examined; (2) an evaluation of an alternative that retains Caspian Tern habitat on East Sand Island and into the future including improving that habitat by placing sand nesting substrate on East Sand Island; and (3) a discussion of Caspian Tern predation in context with other factors influencing ESA listed salmonid recovery," according to the agreement.

Link information: NMFS report
USFWS report

Barry Espenson
NMFS Issues Technical Report on Caspian Terns
Columbia Basin Bulletin, May 31, 2002

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