Abundance and distribution of northern squawfish, walleyes, and smallmouth bass in John Day Reservoir, Columbia river. [Ptychocheilus oregonensis; Micropterus dolomieu; Stizostedion vitreum]

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<0439:AADONS>2.3.CO;2· OSTI ID:5756087

Beamesderfer, R C; Rieman, B E ^[1]

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1. Oregon Dept. of Fish and Wildlife, Clackamas (United States)

The authors used mark-recapture and catch-per-unit effort data to estimate abundances and distributions of three potential predators on juvenile salmonids migrating through John Day Reservoir in 1984-1986. The northern squawfish Ptychocheilus oregonensis was the most abundant predator (estimated population: 85, 316), followed by smallmouth bass Micropterus dolomieu (34,954) and walleye Stizostedion vitreum (15,168). Because of uncertainty in sampling and assumption of the mark-recapture estimator, the combined abundance of these three predators could lie between 50,000 and 500,000. They believe, however, that bias is probably negative, and that any errors should result in conservative estimates. Northern squawfish were common reservoir-wide, but large concentrations occurred immediately below McNary Dam near the head of John Day Reservoir. Walleyes were largely restricted to the upper third of the reservoir, whereas the number of smallmouth bass increased progressively downriver. As judged by abundance and distribution, northern squawfish have by far the greatest potential for predation on juvenile salmonids. They also expect predation to be unevenly distributed in time and space as a result of variations in the number and distribution of predators.

• OSTI ID: 5756087
• 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

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ANADROMOUS FISHES
ANIMALS
AQUATIC ORGANISMS
COLUMBIA RIVER
DAMS
ECOLOGY
FISHES
POPULATION DYNAMICS
PREDATOR-PREY INTERACTIONS
RIVERS
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SURFACE WATERS
VERTEBRATES
WATER RESERVOIRS