After a daylong discussion involving scientists, in the field biologists, policy makers and others the Northwest Power and Conservation Council and staff have suggested a path forward for addressing predatory effects on the Columbia River basin’s salmon, sturgeon and lamprey populations.
Those predators include: native northern pikeminnow; nonnative walleye and bass; avians such as terns, cormorants and gulls; marine mammals such as sea lions; humans; and other beings.
Predation is believed in many cases to be a negative effect on efforts to revive, particularly, salmon and steelhead stocks that are listed under the Endangered Species Act. Efforts had long been under way to dull those effects. Those efforts include programs to remove and/or relocate sea lions, pikeminnow and birds.
An Aug. 9 science-policy exchange convened by the Council in Portland aimed to increase regional understanding of the role of predation and predator control actions in the Columbia River basin and its effects on the ecosystem, as well as discuss the scope of predation issues throughout the basin, in both anadromous fish and resident fish (blocked) areas.
The workshop included discussions of fish, bird and marine mammal predation management and ecosystem predation dynamics, according to a summary report prepared by the Council staff. That report can be found at:
The workshop, which drew 70 participants from across the basin, concluded with a discussion of possible management alternatives to lessen the impact of predation, primarily on salmonids.
“We still need to put out fires,” the Council’s Fish and Wildlife Program director, Tony Grover, told the Council Wednesday. “But policy development is necessary” as regards a more comprehensive plan.
Following the workshop the Council staff identified the following as potential “next steps”:
-- Prepare an inventory of predation problems and actions being taken in the basin to address them. This could be done by developing a map showing where predation is occurring in the basin.
-- Develop a common metric of fish, bird and marine mammal predation and impacts on salmon, sturgeon and lamprey. The lower river tribes are interested in assisting in this effort.
-- Investigate the indirect, or food web, effects of predation; develop a model of predator-prey interactions for basin salmonids in a lifecycle context – based on adult equivalents. Consider starting with mid-Columbia steelhead.
-- Convene the follow-up workshops, if necessary, to further develop and discuss some of the next steps with regional partners.
During the workshop the Independent Scientific Advisory Board’s Robert Naiman pointed out that humans as predators must be taken into account in any management program.
“Predation is an important, natural process which can have a positive influence on populations by culling out the sick, or weaker animals. According to the summary, Naiman pointed out that people kill more large fish through harvest than any other predator in the basin. Harvest results in about 30 percent mortality for adult salmonids. In comparison, total predation mortality on anadromous salmonids by birds and mammals is unlikely to exceed 20 percent.