Beth Sanderson, of the Northwest Fisheries Science Center here in Seattle, just released the results of a study into the effect of invasive species on native salmon. The results are not good.
[Sanderson's team constructed an] explicit database that identified the presence of invasive species in roughly 1800-square-kilometer, hydrologically connected areas throughout Washington, Oregon, and Idaho. The number of invasive species in each area ranged between 86 and 486, the majority being plants and fish.
Sanderson and colleagues assembled reports of predation by six nonindigenous fish species: catfish, black and white crappie, largemouth bass, smallmouth bass, walleye, and yellow perch. Hundreds of thousands to millions of juvenile salmonids were being consumed by these species at just a handful of sites, and for some of the species, salmonids constituted a large fraction of their diet.
Salmon populations on the West Coast have dramatically dropped over the last few years. Till now, most of the research into the decline has focused on direct human impacts like over-fishing, dams, and environmental degradation in the spawning grounds. The indirect effects of invasive species on the salmon ecology has been neglected. This is a rather odd oversight. Every hiker, gardener, and forester in the Northwest is aware of the negative impact of invasive species on dry land.
If Dobbs and the Minutemen would do something about this kind of foreign invasion they might finally be worth a damn.