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Final EIS Released on Reducing Estuary Cormorant
Numbers; Proposes Both Shooting and Egg Oiling

by Staff
Columbia Basin Bulletin, February 6, 2015

(Jamie Francis) Cormorants, like these, and terns are eating nearly 20 million baby salmon a year on East Sand Island, a tiny man-made Oregon island.
A final environmental impact statement released today says the U.S. Army Corps of Engineers would like to take a double-barreled approach in its attempt to reduce double-crested cormorant predation on protected juvenile salmon migrating through the lower Columbia River estuary toward the Pacific Ocean.

The EIS "preferred alternative" lists both the culling of individuals, primarily through shooting, and egg oiling, which suffocates the growing embryo inside the shell, as primary lethal removal methods.

According to the final EIS, annual individual take under the program, which could begin as soon as this spring, would involve 13.5 percent of the colony in years 1 to 4, and associated nest loss and nest oiling rates of 72.5 percent in years 1 to 3 and 13.5 percent in year 4.

"In total, 10,912 individuals and 26,096 total nests are proposed to be taken in all years (3,489, 3,114, 2,408, and 1,902 individuals taken in years 1-4; 9,368, 8,361, 6,466, and 1,902 nests lost in years 1-4)," the document says.

A draft EIS issued in June identified a preferred alternative that would have occurred over four years that would have involved the culling, primarily through shooting, of 18,195 double-crested cormorants.

"In response to comments regarding the cumulative impacts to the western population of double-crested cormorants, the Final Environmental Impact Statement includes Alternative C-1, which is the preferred alternative," according to the EIS introduction. "Alternative C-1 is a modification to Alternative C that includes both nest oiling and culling as the lethal management strategy. Alternative C-1 reduces the total amount of take of individual double-crested cormorants by approximately 40 percent compared to Alternative C, leaving more breeding adults in the population." Alternative C was the preferred alternative outlined in the draft.

In the FEIS, the Corps is proposing to reduce the double-crested cormorant colony size from current levels (approximately 13,000 breeding pairs) to approximately 5,600 breeding pairs on East Sand Island, which is located near the river mouth.

The proposed management plan would include hazing actions and integrated non-lethal methods, in addition to oiling eggs in nests and culling, to discourage nesting on the island and reduce the colony size. Shooting is proposed on East Sand Island and over water from boats. Annual regional monitoring would occur to assess the impacts of the proposed action to the western population of double-crested cormorants. Information gained from this monitoring would be used to adjust future actions through an adaptive management strategy.

Once the management objective for colony size is attained, the Corps is proposing to modify the terrain of East Sand Island on the western portion of the island to reduce the available nesting habitat for double-crested cormorants, the Corps says. This would occur by excavating sand on the western portion of the island to inundate it with tidal flows and placing rock armor along the northern shore to ensure stabilization of the island. To prevent immigration and growth of the colony, the Corps would monitor and perform hazing and monitoring as necessary.

The final EIS and executive summary can be found on the Corps' webpage at

"The Corps and the cooperating agencies on this effort evaluated complex issues to identify a plan with the greatest likelihood of reducing predation on ESA-listed fish," Col Jose Aguilar, the Corps' Portland District commander, said. "Based on the analysis and research undertaken for the EIS, we believe the preferred alternative advances our efforts to reduce predation and satisfy the requirements of the 2014 supplemental biological opinion released by NOAA Fisheries."

The Columbia River Inter-Tribal Fish Commission immediately voiced its support for the proposal.

"Avian predation upon Columbia River salmon stocks has grown to become the single-largest, unchecked impact on their sustainability. The U.S. Army Corps of Engineers' double-crested cormorant EIS is an important first step in addressing one of the significant impacts of avian predation on juvenile salmonids in the lower Columbia River," according to a statement issued by CRITFC.

"From 2010-2013, exploding double-crested cormorant populations nesting on the man-made East Sand Island have consumed at least 74 million juvenile salmonids in the lower Columbia River. These losses equate to 740,000 returning adult salmon and steelhead. After more than a decade of research, we can no longer afford to study cormorant impacts without addressing their threats to salmon recovery," the CRITFC statement says.

The Final Environmental Impact Statement will be available for public review for 30 days after publication of the notice of availability in the Federal Register by the U.S. Environmental Protection Agency. This period is anticipated to begin Feb. 13 and end March 16. Written comments may be sent electronically or by traditional mail to:

Mr. Robert Winters
U.S. Army Corps of Engineer District, Portland
Attn: CENWP-PM-E-14-08/Double-crested Cormorant Final EIS
P.O. Box 2946
Portland, Oregon 97208-2946
Send electronic comments to
The National Environmental Policy Act process was triggered by the presence of what is believed to be the biggest double-crested cormorant nesting colony in the world in the spring and summer at East Sand Island near the mouth of the Columbia River.

The management plan's implementation would potentially be triggered with the signing for a record of decision, likely in March, by the Corps' Northwestern Division commander, Brig. Gen. John S. Kem.

The Corps released a draft EIS in June for public comment. Corps officials say the draft drew 152,000 comments.

Those comments were considered as the Corps prepared the final document released today. Those comments, and the Corps' response to them, are included as an appendix to the EIS.

The colony size now averages about 13,000 breeding pairs each year. The nesting colony on the island has steadily increased in number over the years from 100 breeding pairs in 1989. East Sand is about five miles upstream from the mouth of the Columbia River, closer to Washington than Oregon mainland. It is about 1 kilometer in length and about 200 meters wide at its widest.

The birds are typically at the island during their breeding season, roughly June-August.

The double-crested cormorant is a large black waterbird with a partially orange face and webbed feet. The "western population" of double crested cormorants extends from the Pacific Coast east to the Continental Divide, north into southern British Columbia (following the breeding range of the species), and south to the international border with Mexico.

The East Sand Island colony is estimated to represent about 40 percent of the western population.

The ultimate goal of any "management plan" developed by the Corps would be to drop the annual nesting population by approximately 56 percent, to 5,600 breeding pairs. That's the average during the 1983--2002 "base period," as described in NOAA Fisheries 2014 BiOp.

The goal is to reduce the avian predators' impacts on the survival of 13 salmon and steelhead stocks that are listed under the Endangered Species Act.

The 2014 BiOp supplements a 2008 assessment of salmon and steelhead species survival probabilities, which calculated predation losses at a much smaller cormorant colony size. The plan is to achieve that nesting colony population reduction goal by the end of 2018.

Development and implementation of a double-crested cormorant management plan to reduce avian predation is required under the Corps' ESA consultation with the NOAA Fisheries regarding the operation of the hydropower dams that make up the FCRPS. The Corps operates many of those dams, and manages East Sand Island, which is a naturally occurring island that has been enhanced with the deposit of dredge spoils from the Columbia River navigation channel maintained by the Corps.

While predation rates vary from year to year, double-crested cormorants from East Sand Island on average have consumed 11 million juvenile salmon and steelhead annually over the past 15 years, according to the Corps. In recent years (2011-2013) consumption has averaged 18.5 million per year.

Double-crested cormorants are protected under the Migratory Bird Treaty Act and are native to the Columbia River Estuary.

Average annual double-crested cormorant predation rates of juvenile steelhead originating upstream of the Bonneville Dam have ranged from 2 to 17 percent over the past 15 years (depending on the run, or distinct population segment, and year).

During the NEPA process the Corps evaluated several management alternatives to reduce double-crested cormorant predation impacts.

Non-lethal methods considered include various hazing techniques to reduce colony size and conducting hazing activities off East Sand Island if new colonies establish throughout the Columbia River estuary. Lethal methods considered include take of eggs and shooting individual double-crested cormorants.

The Corps' Portland District is the federal land manager of East Sand Island and the lead agency for the NEPA process. The agency working with its cooperating agencies: U.S. Fish and Wildlife Service, U.S. Department of Agriculture -- Animal Plant Health Inspection Service -- Wildlife Services, the Oregon Department of Fish and Wildlife and the Washington Department of Fish and Wildlife.

A permit from the USFWS is necessary before implementation of the cormorant removal plan.

Related Pages:
Research Tracks Movements, Steelhead Predation by Caspian Terns in Mid-Columbia Basin by Staff, Columbia Basin Bulletin, 1/3/14
Plan Set to Limit Mid-Columba Bird Predation by Staff, Columbia Basin Bulletin, 2/7/14
Final EIS Released On Reducing Estuary Cormorant Numbers; Proposes Both Shooting And Egg Oiling Columbia Basin Bulletin 2/6/15

Final EIS Released on Reducing Estuary Cormorant Numbers; Proposes Both Shooting and Egg Oiling
Columbia Basin Bulletin, February 6, 2015

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