Corps proposes action to manage double-crested cormorant predation of Columbia River fish

 

Double-crested cormorants nest on East Sand Island, located north of Astoria on the Washington

Double-crested cormorants nest on East Sand Island, located north of Astoria on the Washington
coast. The Corps of Engineers has contracted a study of double-crested cormorant nesting sites. (Corps of Engineers photo)

By Diana Fredlund, Public Affairs Office

East Sand Island (Corps of Engineers image)

East Sand Island (Corps of Engineers image)

Seabirds eat fish – it’s what they’re supposed to do. Juvenile Columbia River salmon and steelhead have to travel from their natal streams to the ocean to grow. For the U.S. Army Corps of Engineers, the problem arises when as many as 18 million young fish get eaten by double-crested cormorants in one year, many of which are species listed under the Endangered Species Act.

In early May, during peak nesting season, double-crested cormorants can eat up to one pound of fish per day at East Sand Island. With about 14,000 nesting pairs feeding young chicks, that adds up to a lot of fish.

Add into the equation the need to protect certain species of juvenile salmon and steelhead under the Federal Columbia River Power System Biological Opinion and the Endangered Species Act and it’s an equation that could make a scientist’s head swim.

East Sand Island lies just off the Washington shore a few miles inland from the mouth of the Columbia River jetty system. During much of its history, a wide variety of sea birds like Caspian terns and several species of cormorants made their nests on the small island.

In the late 1990s, the U.S. Army Corps of Engineers began hazing Caspian terns from Rice Island, located deeper in the Columbia River estuary. Federal agencies realized the terns were eating a larger percentage of juvenile salmon and steelhead, known as smolts – and that percentage was impacting Endangered Species Act-listed salmonids. The decision was made to move the birds closer to the Pacific Ocean where a greater variety of prey was available. When the Corps hazed the Caspian terns, many double-crested cormorants relocated with the terns to East Sand Island.

110725-A-AH115-007-web11As part of its dredge operations near the MCR, the Corps placed dredge materials on ESI. The sandy soil offered nesting habitat that many birds, including double-crested cormorants, found inviting: sandy ground, good access to nesting materials and an abundant supply of smolts.

“The Corps has been studying the cormorant population on ESI since 1997, analyzing the birds’ nesting habits and smolt consumption,” said Joyce Casey, chief of the Portland District Environmental Resources Branch. “In 1998 there were about 6,000 breeding pairs on the island; today there are more than 14,000.”

Since then, the size of other cormorant nesting colonies on the West Coast appear to have remained static, while the population at ESI has dramatically increased.

Research focused on understanding how cormorants interact with the habitat and their neighbors – including how dispersing them throughout the region could impact other areas. “We contracted with researchers from Oregon State University’s Oregon Cooperative Fish and Wildlife Research Unit to determine, in part, whether a smaller nesting habitat would make the island less suitable for the cormorants,” Casey said.

It didn’t. Double-crested cormorants seemed unaffected, even when the habitat got downright crowded. “The research showed that as the habitat size decreased, the cormorants just moved in closer to neighboring nests,” Casey said. “Moving the birds to another location in the region isn’t likely, given the abundance of prey in the estuary. We need to address this as a regional issue.”

The Corps is the lead agency for the Columbia River Estuary Double-Crested Cormorant Environmental Impact Statement, which will designate a plan to manage the largest cormorant colony in North America. The U.S. Fish and Wildlife Service, the U.S. Department of Agriculture’s Wildlife Services and the Fish and Wildlife departments of Oregon and Washington are cooperating agencies, which means the plan has input from all agencies.

Researchers from Oregon State University band a cormorant chick at ESI. The band provides data about the bird's range and behavior.  (Corps of Engineers photo)

Researchers from Oregon State University band a cormorant chick at ESI. The band provides data about the bird’s range and behavior. (Corps of Engineers photo)

An EIS is an in-depth document prepared in accordance with the National Environmental Policy Act. NEPA requires federal agencies to consider environmental impacts and evaluate reasonable alternatives in the decision making process.

“Preparing an EIS is a long process,” said Sondra Ruckwardt, Cormorant EIS project manager. “We must document our research methods and results, consult with other agencies and tribal nations, determine the scope of the study – including an opportunity for members of the public to help define the scope, draft the document, provide a public comment period, finalize the document and prepare the Record of Decision for the Corps’ Northwestern Division commander’s signature.”

The Corps has been studying cormorant nesting behavior since NOAA Fisheries released its first FCRPS BiOp in 2000. The BiOp provides guidance for juvenile survival rates through the federal dams on the Columbia and Snake rivers. But as fish passage improvements helped the smolts to safely pass the dams, another threat was waiting in the estuary: many thousands of seabirds looking for food to feed their young, including double-crested cormorants.

“The juvenile survival rates at Corps dams have increased based on improvements we’ve completed, such as the Bonneville juvenile fish passage system and The Dalles spillwall. We have spent millions of dollars improving fish passage since 2000 and there’s not much more we can do to create a plan to manage avian predation, Casey added.

“In the initial BiOp, NOAA Fisheries notified the Corps it needed to come up with a plan to decrease the impact of cormorant predation on ESA-listed juvenile salmon and steelhead,” Ruckwardt said. “It’s impossible for us to protect only the ESA-listed smolts, so the management plan has to protect all the juveniles passing by East Sand Island.”

NOAA Fisheries included a deadline for the Corps to comply with specific target populations in the 2014 update of the BiOp. “The target colony size, with a base cormorant population level of about 5,600 breeding pairs, was determined by NOAA Fisheries as a sustainable predation rate that would allow both double-crested cormorants and ESA-listed smolts to thrive,” Ruckwardt said.

That means the Corps must reduce the colony size by about 8,000 breeding pairs, or 16,000 individuals by the end of 2018. The draft EIS evaluates alternatives to reach this BiOp goal. “The BiOp is an important tool to help the Corps satisfy the requirements of the Endangered Species Act,” Ruckwardt said. “Reducing the cormorant population in the Columbia River estuary back to the base period level is one way that a management plan can address this issue of increased predation. We need to find an alternative that will allow us to meet our 2018 deadline.”

Environmental impact statements, because they address environmental issues, are usually controversial and this EIS is no exception. The draft EIS outlines four alternatives to reach the required target population; the Corps’ preferred alternative, culling up to 16,000 individual birds over the next four years, is based on the best science available to the Corps and the cooperating agencies.

“I think the numbers surprised a lot of people,” Casey said. “Cormorants are long-lived birds, so less lethal measures will not get us to the target population by the 2018 deadline. None of the researchers and biologists working on this EIS got into their careers to kill birds. It’s a difficult decision, but we all believe it is the best solution based on everything we have learned, especially since our goal is to reduce predation throughout the entire 168-mile estuary.”

The controversy is fueled by both sides of the issue. Groups like the Audubon Society of Portland are firmly against the preferred alternative, while groups like the Association of Northwest Steelheaders and tribal fishers feel equally strong about its necessity. The draft EIS is currently available for public review and comment and the Corps is receiving thousands of comments.

“The purpose of the comment period is to give agencies, organizations and individuals the chance to review our data and offer suggestions on something we may have missed,” Ruckwardt said. “We would like to have someone offer another alternative that still gets the Corps to the target population size by 2018 and reduces predation throughout the estuary. Study the data and tell us about something we might have missed.”

Researchers with Oregon State University study double-crested cormorants at East Sand Island in the Columbia River estuary. The research is funded by the U.S. Army Corps of Engineers. Workers build a tunnel near the cormorant colony.

Researchers with Oregon State University study double-crested cormorants at East Sand Island in the Columbia River estuary. The research is funded by the U.S. Army Corps of Engineers. Workers build a tunnel near the cormorant colony.

The Corps and the cooperating agencies are hosting open houses and webinars during the comment period. The meetings offer direct dialog with the biologists and staff who have done the research and understand the process.After the public comment period ends, the team will review and address all the comments in the final document.

At the request of the Audubon Society of Portland, the Corps has extended the comment period by two weeks, meaning comments must be received by Aug. 19.

“All comments we receive become part of the public record and every one will be considered, whether it’s ‘I hate what you’re planning’ or ‘here’s something I think you missed,’” Ruckwardt said. “The final EIS will be complete in fall of 2014 and we’ll have a final management plan by the end of the year.” The Corps will begin implementing the plan in spring 2015.

Ruckwardt and her team know not everyone will be pleased with the final result. “There are strong feelings on both sides of the issue. We know seabirds eat fish. The problem is that the double-crested cormorant colony at East Sand Island is eating ESA-listed juvenile salmon and steelhead at an unsustainable rate.”

To learn more about the Columbia River Estuary Double-Crested Cormorant Environmental Impact Statement visit the Portland District website. An executive summary and the complete document are available at http://www.nwp.usace.army.mil/Missions/Current/CormorantEIS.aspx

Researchers with Oregon State University study double-crested cormorants at East Sand Island in the Columbia

Researchers with Oregon State University study double-crested cormorants at East Sand Island in the Columbia
River estuary. The research is funded by the U.S. Army Corps of Engineers. A researcher records data from banded cormorants near ESI. (Corps of Engineers photo)