Population Dynamics of Channel Catfish in Brownlee Reservoir and the Snake River, Oregon

Abstract

To evaluate a perceived decrease in trophy channel catfish Ictalurus punctatus in Brownlee Reservoir and the Snake River, Oregon, we used gill nets in the reservoir and longlines and slat traps in the river to capture and tag channel catfish larger than 305 mm during 1995-1997. Angler recaptures of tagged fish demonstrated that some channel catfish moved up to 254.3 km upstream and 122.5 km downstream from their initial tagging locations and that 48% of the fish recovered in the reservoir had been tagged in the river and 21% of the fish recovered in the river had been tagged in the reservoir. Recruitment to the river and reservoir stocks between 1984 and 1992 was significantly correlated. Age structure of river and reservoir stocks did not differ significantly. Mean length at age of fish of ages 5-10 was not significantly different in 1996 or 1997, although equations describing growth of the two stocks were significantly different in 1996. Total instantaneous mortality of river and reservoir stocks did not differ significantly, but the angler exploitation rate for channel catfish was significantly higher in the river (0.315) than in the reservoir (0.062) in 1995. The similarity between the population parameters of the river and reservoir stocks suggests that these fish should be managed as one population.