Translocation of prespawn adult Kootenai River white sturgeon

During 2003 and 2004, 25 mature Kootenai River white sturgeon Acipenser transmontanus were dual tagged with sonic and radio transmitters, and translocated upstream approximately 50 km from their current spawning site which is comprised of silt and sand and with low egg survival. The release site was higher gradient and cobble and gravel substrate (canyon reach). The purpose of this study was to join mature white sturgeon with a more suitable incubation and rearing habitat and determine if translocation had legitimacy as a management measure. Residence times in the study varied among years and release groups and movement patterns were difficult to discern. In 2003, all males moved downstream out of the canyon reach within 2 days of release. Of the three females released in 2003, one remained in the canyon reach for 13 days while the other two moved downstream within 4 days. However, five eggs were collected on one substrate mat in the canyon reach in 2003 near river kilometer 261.6, although the eggs were too early in their developmental stage to verify fertilization. In 2004, adults were released in two different time frames, an early and late period. Only one female was part of the early release group in 2004, but three of the remaining six males from this group stayed in the canyon reach for over 3 weeks, the longest of any group. Combining years, males stayed in the canyon reach longer than females; white sturgeon released early in the spawning season stayed in the canyon reach longer. The release of white sturgeon in groups or in areas where other white sturgeon were residing may increase the residency in the study reach. It is feasible to move mature white sturgeon into the more suitable spawning habitats, however, the population level benefits are difficult to determine from this research, and should be weighed against other management and recovery actions.