OSU study: Terns' impact on steelhead runs 'significant'
October 21, 2020
Caspian terns feeding on young fish have a significant impact on runs of steelhead in the Columbia River, research by Oregon State University suggests.
Through detailed analysis of steelhead survival and Caspian tern predation rates, the researchers found that the birds are not only preying on fish that would perish for some other reason, but are adding to the annual death toll by eating steelhead smolts that would have survived without tern pressure.
In scientific terms, the findings indicate that the terns are having an “additive” effect on prey mortality rather than a “compensato...