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

Abstract

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 1,000 m their introduction sites. By age 2, the majority of individuals (58.3%) still remained within 1,000 m of their introduction site, but considerably more individuals had moved downstream, some more than 6,000 m from their introduction site. We observed a significant interaction between age and source population (F _{4, 1077} = 15.45, P < 0.0001) as well as between age and introduction site (F _{41, 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.

Received April 20, 2012; accepted June 3, 2013

ACKNOWLEDGMENTS

Major funding for this work was provided by the National Science Foundation (DEB 0717456). Additional funding was provided by Turner Enterprises, Inc. and Montana Trout Unlimited. We thank Lee Nelson, Pat Clancey, Dan Drinan, Travis Lohrenz, Romie Bahram, Jake Ferguson, Jacqueline Jones, Jennifer Ard, Alex Hopkins, Clint Smith, Tatiana Butler, Ninh Vu, Wes Orr, Buddy Drake, Angela Smith, Mark Sweeney, Reid Koskiniemi, Mike Konsmo, Hillary Billman, and Preston Debele for their assistance in the field. We also thank Ninh Vu, Jenn Ard, and Tatiana Butler for their assistance in the laboratory. Constructive feedback from internal and external reviewers greatly improved the quality of this manuscript. The Montana Cooperative Fishery Research Unit is jointly sponsored by the U.S. Geological Survey, Montana Fish, Wildlife and Parks, Montana State University, and the U.S. Fish and Wildlife Service. The use of trade names or products does not constitute endorsement by the U.S. Government. This study was performed under the auspices of Montana State University institutional animal care and use protocol 18-07.