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]
- 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), Vol. 120:4; ISSN 0002-8487
- Country of Publication:
- United States
- Language:
- English
Similar Records
Abundance and distribution of northern squawfish, walleyes, and smallmouth bass in John Day Reservoir, Columbia river. [Ptychocheilus oregonensis; Micropterus dolomieu; Stizostedion vitreum]
Feeding Activity, Rate of Consumption, Daily Ration and Prey Selection of Major Predators in the John Day Pool : 1983, Annual Report.
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13 HYDRO ENERGY
COLUMBIA RIVER
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FISHES
PREDATOR-PREY INTERACTIONS
ANADROMOUS FISHES
FEEDING
POPULATION DYNAMICS
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WATER RESERVOIRS
ANIMALS
AQUATIC ORGANISMS
DEVELOPED COUNTRIES
FEDERAL REGION X
NORTH AMERICA
RIVERS
STREAMS
SURFACE WATERS
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VERTEBRATES
540310* - Environment
Aquatic- Basic Studies- (1990-)
130600 - Hydro Energy- Environmental Aspects