Impacts of Predation

The Costly Impact of Predation and Conflicting Federal Statutes on Native and Endangered Fish Species 









February 10, 2016


Thank you for providing the Department of the Interior the opportunity to submit this statement for today’s hearing.  It is our understanding that the Subcommittee is interested in the intersection between the Migratory Bird Treaty Act (MBTA) and the Endangered Species Act (ESA), as they relate to the protection and recovery of endangered salmon in the North Pacific.  This statement describes the U.S. Fish and Wildlife Service’s (Service’s) role in the Federal management of double-crested cormorants and Caspian terns, as required by the 2008 and 2014 Federal Columbia River Power System Supplemental Biological Opinions (BiOPs) for endangered salmon.  This statement also provides an update on those management efforts. 

Endangered Species Act 

Under Section 7(a)(2) of the ESA, all Federal agencies must ensure that any action they authorize, fund or carry out is not likely to jeopardize the continued existence of a listed species or result in the destruction or adverse modification of designated critical habitat.  If the Federal agency determines that an action may affect a listed species, then either formal or informal consultation with the Service or the National Marine Fisheries Service (NMFS) is appropriate.  If a listed species will be adversely affected either directly or indirectly due to the Federal action, then the Service or NMFS prepares a biological opinion (BiOp) that includes a review of scientific information considered and a detailed discussion of the effects of the action on the listed species or designated critical habitat in the action area.  If the proposed action is not likely to jeopardize the continued existence of a listed species, but incidental take is anticipated to be likely, then reasonable and prudent measures are included to minimize the impact of the incidental take.  If the action is likely to jeopardize a listed species or adversely modify designated critical habitat, then reasonable and prudent alternatives are identified during consultation that can be implemented in a manner consistent with the intended action, are economically and technically feasible, and would avoid the likelihood of jeopardy for species or adverse modification for critical habitat. 

The action agency is responsible for initiating the Section 7 consultation process by contacting either the Service or NMFS, depending on the ESA-listed species involved. The Service has responsibility for terrestrial, freshwater, and certain marine listed species and anadromous fish, including bulltrout and sturgeon, as well as sea otters, and manatees. NMFS is responsible for implementing the ESA Section 7 consultation for all other marine and anadromous fish species that are listed under the ESA. 

The 2014 BiOp [1] and the 2008 BiOp [2], prepared by NMFS, in cooperation with the Service and the Action Agencies (U.S. Army Corps of Engineers, Bonneville Power Administration, and Bureau of Reclamation), comprehensively review the salmon lifecycle and require actions to address an array of factors that affect salmon survival and recovery, including operations at the dams in the FCRPS to improve juvenile and adult passage, estuary and tributary habitat improvements, and predator management.  In both BiOps, NMFS has identified the management of avian predators as an important component of the overall program to improve the status of listed salmonid species. They specifically address the impacts of predation on listed salmonid species from double-crested cormorants, Caspian terns, and other bird species. 

Migratory Bird Treaty Act

The Service is responsible for implementing and enforcing protections for native bird species under the MBTA (16 U.S.C. 703-711).  Double-crested cormorants (Phalacrocorax auritus) and Caspian terns (Sterna caspia) are among 1,027 species protected under the MBTA, which was first enacted in 1918 to implement a treaty signed in 1916 between the United States and Great Britain (for Canada) for the conservation of birds that migrate between the two nations.  The United States went on to become a party to three similar treaties with Mexico, Japan, and Russia.  Each migratory bird treaty contains a prohibition against “take” of protected birds, which under the MBTA includes killing, capture, sale, trade, barter, pursuit and other activities (16 U.S.C. 703). Each treaty has a list of species that the parties have agreed to protect through the treaty provisions.  The MBTA has been amended by Congress periodically to ensure that this statute fully and faithfully implements United States obligations under all four of these treaties. Cormorants and terns are protected under a 1972 amendment to the 1936 United States-Mexico migratory bird treaty entitled the Convention for the Protection of Migratory Birds and Game Mammals [3].  Under the MBTA, take is prohibited without a permit from the Secretary of the Interior (or designee), but no permit is required to harass or disturb protected birds, unless (1) the species is listed as threatened or endangered, (2) the species involved are bald or golden eagles, or (3) the harassment or disturbance will result in take. 

To reduce avian predation on juvenile salmon, the 2008 BiOp calls for the U.S. Army Corps of Engineers (Corps) to develop and implement a Caspian Term Management Plan, and the 2014 BiOp calls for the Corps to develop and implement a Double-Crested Cormorant Management Plan.  The 2014 BiOp calls for the monitoring of predation on endangered salmonids by cormorants, terns and gulls.

Double-Crested Cormorant Management Plan

The 2008 BiOp did not single out the impact of cormorant predation on juvenile endangered salmonids.  However, one of the assumptions in the 2008 BiOp analysis was that specific rates of predation on juvenile endangered salmon estimated for the Base Period would remain unchanged into the future.  Instead, the double-crested cormorant (DCCO) nesting population and predation rates increased substantially during 2003–2009.  As a result, the productivity of interior Columbia basin steelhead populations was about 3.6 percent lower than assumed for the Current Period in the 2008 BiOp analysis, and that of interior Columbia basin stream-type spring- and summer-run Chinook salmon and ocean-type SR fall Chinook salmon was about 1.1 percent lower than assumed. 

The 2014 BiOp, therefore, indicates that reduction of the DCCO nesting population in the Columbia River Estuary is necessary to address mortality of juvenile salmonids by migratory birds.  The RPA to address this impact on juvenile endangered salmon requires the reduction of the DCCO nesting colony on East Sand Island to no more than 5,380 to 5,939 nesting pairs, in order to reduce their predation on juvenile salmonids in the estuary.  In 2014, there were an estimated 12,150 DCCO nests on East Sand Island.  The Corps is responsible for implementing this requirement. 

The Corps prepared a DCCO Management Plan that proposes to reduce nesting cormorants on East Sand Island by 13.5 percent over 4 years, which would mean removal of approximately 11,000 cormorants in total.  The Corps then applied for and received a depredation permit from the Service for calendar year 2015, authorizing the take of 3,489 DCCO and 5,879 DCCO nests through January 31, 2016.  Per Federal regulations, a depredation permit for migratory birds may be in effect for a maximum of one year.  The Corps will apply for renewal of its depredation permit each year as described in the DCCO Management Plan. 

In issuing this and all MBTA depredation permits, the Service ensures that the requested action is consistent with the requirements of the MBTA and that the requested action is likely to provide short-term relief from bird damage.  Specifically, in issuing this type of permit, the Service ensures that the action: (1) meets the permit issuance requirements and criteria (See 50 CFR § 13.21), including that the action does not potentially threaten a wildlife or plant population (See 50 CPR§ 13.21(b)(4)); (2) is consistent with the Federal depredation permit regulation (50 CPR§ 21.41); and (3) is compatible with the conservation of the migratory bird species as required by the MBTA. The DCCO depredation permit that was issued to the Corps is based on the recommendations of the final DCCO Management Plan, for which the Corps completed a Final Environmental Impact Statement (FEIS) in 2015 [4].  The Service was a cooperating agency on the FEIS.  The FEIS evaluates a range of alternatives to reduce cormorant predation on juvenile salmonids and considers a number of different scientific analyses.  The 2015 Cormorant FEIS presents the scientific analyses that were considered in preparing these alternatives. 

For example, the FEIS took into consideration research funded by the Corps on the potential impacts associated with cormorant consumption of juvenile salmonids in the Columbia River Estuary as early as 1997.  This research included monitoring of the size, productivity, and diet of DCCO nesting colonies in the estuary, including on East Sand Island.  Other studies considered in the FEIS were conducted in 2004 on non-lethal management techniques, including habitat enhancement, methods to attract cormorants to habitat outside the Columbia River Estuary, and methods to dissuade cormorants from nesting on East Sand Island.  In addition, development of management objectives for the cormorant colony at East Sand Island relied on the smolt survival gap (the difference between cormorant predation on juvenile salmonids between the base period (1983-2002) and the current period (2003-2009)). 

The 2014 BiOp also thoroughly addresses the issue of compensatory mortality.  The idea of compensatory predation mortality argues that at least some portion of the fish consumed by predators would have died from other factors subsequent to the predation event.  As stated in the 2014 BiOp, regardless of the magnitude of compensatory mortality associated with cormorant predation in the Columbia River, there is no evidence that it has changed over time. Therefore, if the cormorant population is reduced to its level during the Base Period (between 5,380 and 5,939 pairs), as described in the RPA, the impact of cormorant predation on salmonid survival (including any compensatory effects) should return to the same level that occurred during the Base Period.

For the FEIS, new analyses were conducted to understand the environmental factors influencing predation by cormorants on salmon and steelhead.  The 2014 BiOp also evaluated the significance of juvenile salmonid survival as a component of the salmon lifecycle.  It was determined that reducing avian predation would help to improve safe passage for juvenile endangered salmonids through the Columbia River Estuary.


Our understanding is that the Corps will continue to implement its DCCO Management Plan, as described in Chapter 5 of the 2015 Cormorant FEIS.  Chapter 5 of the FEIS proposes annual take levels, which would allow the Corps to meet the 2018 targets in the 2014 BiOp.  These numbers are proposals only and will be adjusted accordingly through annual review by an Adaptive Management Team that is comprised of representatives from the Corps, the Service, NMFS, USDA Animal and Plant Health Inspection Service (APHIS), and state and tribal entities. 

The Corps’ depredation permit expired on January 31, 2016.  As of October 28, 2015, 2,346 individual cormorants have been culled and 5,089 nests have been oiled.  In 2015, the Corps did not cull the total number of birds authorized under the 2015 depredation permit due to the late start of management activities.  The Corps has submitted a permit renewal request to the Service for authorization of the proposed depredation permit activities in 2016, and it is currently under review. 

Caspian Tern Management Plan

The potential impact of nesting Caspian terns on East Sand Island on juvenile salmonids was recognized long before the 2008 BiOp called for the Corps to develop and implement a Caspian Tern Management Plan.  The Service, in cooperation with NMFS and the Corps, completed the Caspian Tern Management to Reduce Predation of Juvenile Salmonids in the Columbia River Estuary FEIS [5] in 2005, which describes and evaluates four alternatives for reducing Caspian tern predation on juvenile salmonids in the Columbia River Estuary, in compliance with the terms of a Settlement Agreement pertaining to tern and salmon management in the estuary. 

Under the Preferred Alternative, nesting habitat for the Caspian tern would be redistributed away from East Sand Island to other locations throughout the Pacific Coast region.  This redistribution would be achieved by creating new or enhancing existing tern nesting habitat in Washington, Oregon (outside the Columbia River Basin), and California and ultimately reducing the tern nesting site on East Sand Island to about 1 to 1.5 acres.  To ensure a suitable network of sites is available for terns on a regional scale, the FEIS proposed to replace twice the amount of nesting habitat that was being used by the terns and would be lost on East Sand Island.  Since terns nested on an average of 4.4 acres on East Sand Island from 2001 to 2004, approximately 6 to 7 acres of replacement habitat were needed to replace the loss of nesting habitat on East Sand Island.  This FEIS was used to describe information available on the impact of Caspian terns on juvenile salmonids, and it anticipated the RPA that would be undertaken would be pursuant to the FEIS’ Preferred Alternative.  Through an adaptive management process, the plan was updated in 2015 [6] and the acreage prepared for tern nesting on East Sand Island was reduced to 1.0 acres. 

To date, 11 alternative nesting habitat islands totaling 8.18 acres of available habitat have been constructed/enhanced at interior and coastal locations.  Tern nesting habitat on East Sand Island has been reduced from 6 acres to 1.0 acre, which has reduced the colony from a pre-management level of about 9,000 pairs to 6,240 pairs.  The last reduction of available habitat on East Sand Island was completed prior to the 2015 breeding season.  This occurred simultaneous to the full dissuasion of the tern colonies on Goose and Crescent Island colonies that are inland in the Columbia River Basin.  Due to the need for terns to relocate to available habitat, it may take several more years to reach the 3,125 – 4,375 breeding pair goal and the associated reduction of juvenile salmonid predation expressed in the 2005 Caspian Tern FEIS. 

At the time of completion of the 2014 BiOp, only Caspian terns nesting on Goose Island in Potholes Reservoir and Crescent Island in the Columbia River were slated for management action (e.g. reductions in habitat).  Survival benefits to Upper Columbia River steelhead and spring Chinook are expected to increase since nesting dissuasion actions began in early 2014 on Goose Island. Additional benefits to Upper Columbia and Snake River juvenile salmonids should follow now that both alternative tern habitat has been developed outside the Columbia River basin and nesting dissuasion actions have been in full force at Crescent Island since early 2015.


The 2014 BiOp reports that the impacts of Caspian terns and other birds, such as gulls and pelicans, are largely addressed in the RPAs of the 2008 BiOp.



The Federal agencies remain committed to working together to implement the 2014 BiOp and the full complement of actions described in it to reduce avian mortality on juvenile endangered salmonids in the Columbia River.  We are focused on the needs of listed species, as required under the ESA, as well as the United States’ obligations to conserve migratory birds under the MBTA in compliance with our international treaty obligations.  Due care and diligence, quality information, and continued collaboration with all affected jurisdictions will continue as the 2014 BiOp enters its second year of implementation, and beyond.


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