Rates of consumption of juvenile salmonids and alternative prey fish by northern squawfish, walleyes, smallmouth bass, and channel catfish in John Day Reservoir, Columbia River. [Ptychocheilus oregonensis; Stizostedion vitreum; Micropterus dolomieu; Ictalurus punctatus; Oncorhynchus spp]

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<0421:ROCOJS>2.3.CO;2· OSTI ID:6031416

Vigg, S; Poe, T P; Prendergast, L A; Hansel, H C ^[1]

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1. Fish and Wildlife Service, Cook, WA (United States)

Adult northern squawfish Ptychocheilus oregonesis, walleyes Stizostedion vitreum, smallmouth bass Micropterus dolomieu, and channel catfish Ictalurus punctatus were sampled from four regions of John Day Reservoir from April to August 1983-1986 to quantify their consumption of 13 species of prey fish, particularly seaward-migrating juvenile Pacific salmon and steelhead (Oncorhynchus spp.). Consumption rates were estimated from field data on stomach contents and digestion rate relations determined in previous investigations. For each predator, consumption rates varied by reservoir area, month, time of day, and predator size or age. The greatest daily consumption of salmonids by northern squawfish and channel catfish occurred in the upper end of the reservoir below McNary Dam. Greatest daily predation by walleyes and smallmouth bass occurred in the middle and lower reservoir. Consumption rates of all predators were highest in July, concurrent with maximum temperature and abundance of juvenile salmonids. Feeding by the predators tended to peak after dawn and near midnight. Northern squawfish below McNary Dam exhibited this pattern, but fed mainly in the morning hours down-reservoir. The daily ration of total prey fish was highest for northern squawfish over 451 mm fork length, for walleyes 201-250 mm, for smallmouth bass 176-200 mm, and for channel catfish 401-450 mm. Averaged over all predator sizes and sampling months (April-August), the total daily ration (fish plus other prey) of smallmouth bass was about twice that of channel catfish, northern squawfish, and walleyes. However, northern squawfish was clearly the major predator on juvenile salmonids.

• OSTI ID: 6031416
• 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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