We often capture non-native predator species in West Coast tributaries during juvenile salmon outmigration monitoring. It is not uncommon to catch a fish in the process of consuming another fish, or witness a fish regurgitate its previous meal soon after capture. When we think of predators, our first thought is usually trophy size striped or largemouth bass, but small fish are predators too.
Recently, a report published in BioScience “Nonindigenous Species of the Pacific Northwest: An Over looked Risk to Endangered Salmon?” found in the Columbia basin introduced predators consume hundreds of thousands to millions of juvenile Pacific salmonids at just a handful of sites. The report also notes that the effect of non-indigenous species on salmon could equal or exceed that of four commonly addressed causes of adverse impacts; habitat alteration, harvest, hatcheries, and the hydrosystem.
Download the report here