Kokanee Stock Status and Contribution Cabinet Gorge Hatchery, Lake Pend Oreille, Idaho: Annual Progress Report FY 1988.

摘要

The kokanee Oncorhynchus nerka rehabilitation program for Lake Pend Oreille continued to show progress during 1988. Estimated kokanee abundance in early September was 10.2 million fish. This estimate is 70% higher than 1987 and 140% higher than the populations's low point in 1986. Increased population size over the past two years is the result of two consecutive strong year classes produced from high recruitment of hatchery and wild fry. High recruitment of wild fry in 1988 resulted from good parental escapement (strong year class) in 1987 and relatively high fry survival. Hatchery fry made up 51% of total fry recruitment (73% of total fry biomass), which is the largest contribution since hatchery supplementation began in the 1970s. High hatchery fry abundance resulted from a large release (13 million fry) from Cabinet Gorge Hatchery and excellent fry survival (29%) during their first summer in Lake Pend Oreille. Improved fry release strategies enhanced survival, which doubled from 1987 to 1988 and was ten times higher than survival in 1986. Our research goal is to maintain 30% survival so we are very optimistic, but need to replicate additional years to address annual variability. 27 refs., 24 figs., 3 tabs.