Invasive species cause biodiversity loss and about $120 billion in annual damages in the U.S. alone. Despite plentiful evidence that invasive species can change food webs, how invaders disrupt food webs and native species over time has remained unclear.
When warmwater fish species like bass, walleye and crappie that are not native to the Pacific Northwest, but prized by some anglers, overlap with baby spring chinook salmon in reservoirs in Oregon’s Willamette River they consume more baby salmon than native predatory fish per individual, new research found.
At the end of the first spring in which biologists have been allowed by federal permit to lethally remove both California and Steller sea lions in the Columbia and lower Willamette rivers, fisheries biologists have stopped the removal activity as sea lions have left Bonneville Dam and both rivers for coastal rockeries.
The Independent Scientific Advisory Board has released an analysis of two studies offering differing views on the effectiveness of avian predation control measures in the Columbia River basin. The scientists say further comparative research is needed to determine if hazing and killing terns and cormorants are boosting steelhead smolt-to-adult returns.
The Washington Department of Fish and Wildlife is taking public input on its state status review for Steller sea lions.
On the heels of a successful and significant reduction of lake trout in Lake Pend Oreille, Idaho is now using some of the same methods – gillnetting and an angler rewards program – it used to fight lake trout in a new effort to reduce the population of invasive walleye in the lake.
Older Chinook salmon may die in the ocean more often than previously thought, according to a life cycle simulation created by Alaska researchers.
During the fall 2019 and spring 2020 monitoring seasons at Bonneville Dam, sea lions continued to prey on salmon, steelhead and sturgeon, but the proportion of California sea lions is continuing to drop while that of steller sea lions continues to rise, according to a draft annual pinniped report by the U.S. Army Corps of Engineers.
Juvenile salmon run the gamut of predators – birds, other fish and pinnipeds – as they migrate from their rearing grounds far upstream in the Columbia River basin all the way to the ocean, but they also are confronted with predators as they enter the ocean.