Juvenile Movement among Different Populations of Cutthroat Trout Introduced as Embryos to Vacant Habitat

Translocations are frequently used to increase the abundance and range of endangered fishes. One factor likely to affect the outcome of translocations is fish movement. We introduced embryos from five Westslope Cutthroat Trout Oncorhynchus clarkii lewisi populations (both hatchery and wild) at five different locations within a fishless watershed. We then examined the movement of age-1 and age-2 fish and looked for differences in movement distance among source populations and among introduction sites; we also examined the interactions among age, population, and introduction site. At age 1, most individuals (90.9%) remained within 1,000m their introduction sites. By age 2, the majority of individuals (58.3%) still remained within 1,000m of their introduction site, but considerably more individuals had moved downstream, some more than 6,000m from their introduction site. We observed a significant interaction between age and source population (F-4,F- 1077= 15.45, P < 0.0001) as well as between age and introduction site (F-41,F- 1077 = 11.39, P < 0.0008), so we presented results in the context of these interactions. Within age-groups, we observed differences in movement behavior among source populations and among donor populations of Westslope Cutthroat Trout. We discuss these findings in light of previous research on juvenile salmonid movement.