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BiologySpawns on shallow gravel bars in freshwater lakes or the mouths of creeks flowing into lakes. Ammocoetes larvae occur in silt, mud, or sand in quiet water (Ref. 5723). Ammocoetes are found in inlet streams within 100 m of two lakes in Vancouver Island, British Columbia. Ammocoetes and recently metamorphosed individuals are mostly found along the edges of lakes. Adult life span believed to be at least 2 years. Adults parasitic on fishes (Oncorhynchus clarkia and O. kisutch) in freshwater lakes throughout the year. Wounds produced known to penetrate deeply into the musculature or even reach the body cavity of hosts. Up to three adults have been recorded attached to a host. Adults are known experimentally to be able to survive in salt water, but apparently remain in fresh water despite the absence of barriers preventing access to the sea. Adults in spawning readiness collected from shallow gravel bars between 1 June and 23 August. Between 50 and 80% of fishes, mostly salmonids, in Lake Cowichan and Mesachie Lake show evidence of attacks from this lamprey, and based on the severity of the wounds inflicted, an estimated 15% of these attacks would probably result in the death of the host (Ref. 89241).