The U.S. Army Corps of Engineers has launched a process aimed at determining what management actions might be undertaken to reduce avian predators’ impacts on protected Columbia and Snake River salmon and steelhead in the mid-Columbia plateau region.
The federal agency that operates many of the dams in the Federal Columbia River Power System held a public scoping meeting Wednesday in in Kennewick, Wash., to explain predation issues and gather input that might be useful in developing a draft “Inland Avian Predation Management Plan” aimed at Caspian terns and double-crested cormorants.
Such a plan is in place to reduce Caspian tern predation in the Columbia River estuary with a major goal of relocating fish-eating birds to areas where they won’t feed on juvenile salmon that are listed under the Endangered Species Act. A plan is also being developed to reduce cormorant consumption of salmonids in the lower Columbia.
Once finalized, the mid-Columbia plan would affect actions undertaken for management of avian predation on juvenile salmonids in the vicinity of the Columbia and Snake rivers, from Bonneville Lock and Dam near Cascade Locks, Ore., up to Lower Granite Lock and Dam in southeast Washington, near Pomeroy. Bonneville is located 146 upstream from the mouth of the Columbia and Lower Granite is about 108 miles upstream from the Columbia’s confluence with the Snake. In between are six hydro projects and seven reservoirs.
Recent scientific studies suggest that the most significant impact of avian predation on the Columbia Plateau is occurring by certain avian species, including Caspian terns and double-crested cormorants. These studies have identified nesting colonies of terns at Goose Island in Potholes Reservoir , Crescent Island (seven miles downstream from the Columbia’s confluenece with the Snake River), and Blalock Islands in the Columbia reservoir upstream of John Day Dam and cormorants at Foundation Island, in the Columbia near Pasco, Wash., as contributors to predation on ESA-listed salmonid species in the Columbia River.
The studies have also identified other predatory bird species in the area -- including American white pelican, California gull and ring-billed gull -- that are having a lesser impact on out-migrating anadromous salmonids.
More than 100,000 piscivorous (fish-eating) colonial birds, representing five different species nesting at 18 different colonies, were documented in the Columbia Plateau region during 2004-2009, according to the Corps.
According to analysis conducted last year for the Corps the “greatest potential benefit” from reductions in predation by birds from a single colony in the Columbia Plateau region was for Upper Columbia River steelhead when predation by Caspian terns nesting at Goose Island (in Potholes Reservoir near Othello, Wash.), was reduced; up to a 4.2 percent (hatchery-raised smolts) or 3.2 percent (wild smolts) if predation were completely eliminated and compensatory mortality did not occur.
“Potential benefits for Snake River ESUs were lower, in part because significant portions of those ESUs are transported and thus inaccessible to avian predators in the Columbia Plateau region,” according the analysis conducted by researchers from Oregon State University and from Real Time Research Inc.
“The greatest potential benefit possible for a Snake River salmonid ESU/DPS resulting from reductions in predation by birds from a single colony was for steelhead, if predation by Caspian terns nesting at the Crescent Island colony (near Pasco, Wash.) was eliminated (0.5 percent increase” in the average annual population growth rate).
The researchers examined the potential benefits of reducing avian predation associated with five colonies of piscivorous waterbirds in the Columbia Plateau region for three evolutionarily significant units of chinook salmon, one ESU of sockeye salmon, and distinct population segments of steelhead trout from the Upper Columbia River and Snake River basins. The analysis involved using predation rate data based on recoveries of smolt passive integrated transponder tags at bird colonies.
The analysis-report released in September 2011 said that reducing avian predation in the mid-Columbia in itself would not solve the salmon problems but might “contribute to broader efforts towards recovery of threatened and endangered stocks, and potentially offer modest benefits for non-listed populations of anadromous salmonids (e.g., coho salmon) or other species of conservation concern that we did not consider (e.g., Pacific lamprey.”
The Inland Avian Predation Management Plan will incorporate management of bird species identified through recent research efforts to be having the highest predation on juvenile salmonids during their outmigration on the Columbia River upstream of Bonneville Dam. This includes the eight federal Columbia and Snake River dams and adjacent inland areas in Oregon, Idaho, and Washington (Columbia Plateau). As part of developing the plan, the geographic scope will also include those areas where potential habitat for bird relocation may occur throughout the Pacific Northwest.
The management plan, which would be vetted through a public National Environmental Policy Act process leading to an environmental assessment, will focus on management of lands and associated shallow-water habitat while improvement of predation deterrent programs at the Corps’ lower Snake and Columbia River dams will continue to be addressed.
The plan development effort by the Corps, Bonneville Power Administration and the Bureau of Reclamation (the action agencies) is part of the overall efforts to comply with NOAA Fisheries’ 2008 FCRPS biological opinion. That ESA documents outlines actions the Fisheries Service deems necessary to avoid jeopardizing listed salmon and steelhead stocks. The Corps and Bureau operates the FCRPS hydro projects; Bonneville markets power generated in the federal system.
NOAA Fisheries recommends strategies to improve juvenile salmon and steelhead survival with the expectation that this will contribute to an improvement in adult returns and thereby recovery of ESA-listed fish species. Managing avian predators to address salmon predation would add to and complement other recovery efforts, thereby contributing to the overall recovery of ESA-listed salmonids in the Columbia River Basin.
For information about the Inland Avian Predation Management Plan go to www.nww.usace.army.mil/planning/Avian/default.asp