An epidemiological survey of a conservation hatchery: British Columbia's Living Gene Bank of steelhead trout (Oncorhynchus mykiss )

A Living Gene Bank (LGB) program is part of the "Steelhead Recovery Plan" initiated by the British Columbia government in 1998 to supplement wild populations. To address possible disease concerns, LGB and wild fish were surveyed for macroparasitic and microparasitic presence and prevalence. It was found that: (1) infected smolt and river residents from the LGB program had poorer body condition, (2) large individuals may be less impacted than smaller individuals, (3) individuals of steelhead x cutthroat ancestry (hybrids) were more susceptible to a facultative infection, and (4) hybrids may vary in susceptibility to specific pathogens. The complexity of disease issues suggests that a fish health monitoring program is necessary to determine the effects of release abundance and altered life history on the epidemiology of the wild populations.