Evidence of natural reproduction of aquaculture-escaped Atlantic salmon ina coastal British Columbia river

We present evidence of the first successful natural spawning of Atlantic sa lmon (Salmo salar) documented on the Pacific coast of North America. Twelve juvenile Atlantic salmon composed of two year classes were captured in the Tsitika River, British Columbia. We analyzed restriction-length polymorphi sms of PCR-amplified 5S rDNA and mtDNA to confirm that these individuals we re Atlantic salmon. Scale analysis strongly suggested they were the product s of natural spawning by feral adults. The gut contents, size, and conditio n of these individuals suggest that Atlantic salmon are successfully maturi ng in the Tsitika River, British Columbia. This event has raised concerns t hat the presence and possible establishment of feral Atlantic salmon may fu rther jeopardize the continued persistence of already fragile native Pacifi c salmonids through competition for resources and occupation of niches that are currently underutilized.