Kokanee Stock Status and Contribution of Cabinet Gorge Hatchery, Lake Pend Oreille, Idaho, 1989 Annual Progress Report.

Abstract

The kokanee Oncorhynchus nerka rehabilitation program for Lake Pend Oreille continued to show progress during 1989. Estimated kokanee abundance in late August was 7.71 million fish. Decreased population size is the result of lower hatchery and wild fry recruitment and low age 1+ survival. Lower recruitment of wild fry in 1989 resulted from a smaller parental escapement in 1988 and lower wild fry survival. Six fry release strategies were evaluated in 1989. Two groups were released in Clark Fork River to help improve a spawning run to Cabinet Gorge Hatchery. Survival from the mid-summer release, which was barged down Clark Fork River to avoid low flow problems, was not significantly different from the early release. The final assessment of these release strategies will be evaluated when adults return to Cabinet gorge Hatchery in 1992 and 1993. Fry released to support the Sullivan Springs Creek spawning run also survived will in 1989. Two open-water releases were made during early and mid-summer. 30 refs., 26 figs., 2 tabs.