Estimated loss of juvenile salmonids to predation by northern squawfish, walleyes, and smallmouth bass in John Day Reservoir, Columbia River. [Oncorhynchus spp. ; Ptychocheilus oregonensis; Stizostedion vitreum; Micropterus dolomieu; O. tshawytscha]

Journal Article · Mon Jul 01 04:00:00 EDT 1991 · Transactions of the American Fisheries Society; (United States)

DOI:https://doi.org/10.1577/1548-8659(1991)120<0448:ELOJST>2.3.CO;2· OSTI ID:5756085

Rieman, B E; Beamesderfer, R C ^[1]; Vigg, S; Poe, T P ^[2]

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1. Oregon Dept. of Fish and Wildlife, Clackamas (United States)
2. Fish and Wildlife Service, Cook, WA (United States)

The authors estimated the loss of juvenile salmonids Oncorhynchus spp. to predation by northern squawfish Ptychocheilus oregonensis, walleyes Stizostedion vitreum, and smallmouth bass Micropterus dolomieu in John Day Reservoir during 1983-1986. Their estimates were based on measures of daily prey consumption, predator numbers, and numbers of juvenile salmonids entering the reservoir during the April-August period of migration. They estimated the mean annual loss was 2.7 million juvenile salmonids. Northern squawfish were responsible for 78% of the total loss; walleyes accounted for 13% and smallmouth bass for 9%. Twenty-one percent of the loss occurred in a small area immediately below McNary Dam at the head of John Day Reservoir. The authors estimated that the three predator species consumed 14% of all juvenile salmonids that entered the reservoir. Mortality changed by month and increased late in the migration season. Monthly mortality estimates ranged from 7% in June and 61% in August. Mortality from predation was highest for chinook salmon O. tshawytscha, which migrated in July and August. Despite uncertainties in the estimates, it is clear that predation by resident fish predators can easily account for previously explained mortality of out-migrating juvenile salmonids. Alteration of the Columbia River by dams and a decline in the number of salmonids could have increased the fraction of mortality caused by predation over what is was in the past.

• OSTI ID: 5756085
• Journal Information: Transactions of the American Fisheries Society; (United States), Journal Name: Transactions of the American Fisheries Society; (United States) Vol. 120:4; ISSN 0002-8487; ISSN TAFSA
• Country of Publication: United States
• Language: English

Related Subjects

13 HYDRO ENERGY
130600 -- Hydro Energy-- Environmental Aspects
54 ENVIRONMENTAL SCIENCES
540310* -- Environment
Aquatic-- Basic Studies-- (1990-)
ANADROMOUS FISHES
ANIMALS
AQUATIC ORGANISMS
COLUMBIA RIVER
DAMS
ECOLOGY
ENVIRONMENTAL IMPACTS
FEEDING
FISHES
MORTALITY
POPULATION DYNAMICS
PREDATOR-PREY INTERACTIONS
RIVERS
STREAMS
SURFACE WATERS
VERTEBRATES
WATER RESERVOIRS