Preliminary Estimates of Loss of Juvenile Anadromous Salmonids to Predators in John Day Reservoir and Development of a Predation Model : Interim Report, 1986.
We made preliminary estimates of the loss of juvenile salmonids to predation by walleye, Stizostedion v. vitreum, and northern squawfish, Ptychocheilus oregonensis, in John Day Reservoir in 1984 and 1985 using estimates of predator abundance and daily prey consumption rates. Preliminary estimates may be biased and may be adjusted as much as 30%, but indications are that predation could account for the majority of unexplained loss of juvenile salmonids in John Day Reservoir. Total loss was estimated at 4.1 million in 1984 and 3.3 million in 1985. Northern squawfish consumed 76% and 92% of these totals, respectively. The majority of loss occurred in mid reservoir areas, but loss in a small area, the boat-restricted zone immediately below McNary Dam, was disproportionately large. Peaks in loss in May and July corresponded with peaks in availability of salmonids. Estimated mortality from predation for April through June in 1984 and 1985 was 9% and 7% respectively, for chinook salmon, Oncorhynchus tshawytscha, and 10% and 15% for steelhead, Salmogairdneri. Mortality was variable with time but tended to increase over the period of migration. Mortality of chinook was estimated at 26% to 55% during July and August. A model of predation in John Day Reservoir is outlined. The model includes a predation submodel that can calculate loss from predator number and consumption rate; a population submodel that can relate predator abundance and population structure to recruitment, exploitation, natural mortality and growth; and a distribution submodel that can apportion predators among areas of the reservoir over time. Applications of the model are discussed for projecting expected changes in predation over time and identifying management alternatives that might limit the impact of predation.
- Research Organization:
- Oregon Department of Fish and Wildlife (ODFW)
- Sponsoring Organization:
- United States. Bonneville Power Administration.
- DOE Contract Number:
- AI79-82BP35097
- OSTI ID:
- 6386384
- Report Number(s):
- DOE/BP35097-4; ON: DE87010557
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
- Country of Publication:
- United States
- Language:
- English
Similar Records
Feeding Activity, Rate of Consumption, Daily Ration and Prey Selection of Major Predators in John Day Reservoir, 1985: Annual Report.
Feeding Activity, Rate of Consumption, Daily Ration and Prey Selection of Major Predators in the John Day Pool : 1983, Annual Report.
Related Subjects
SALMON
PREDATOR-PREY INTERACTIONS
TROUT
COLUMBIA RIVER
DAMS
JUVENILES
MATHEMATICAL MODELS
MIGRATION
WATER RESERVOIRS
ANADROMOUS FISHES
ANIMALS
AQUATIC ORGANISMS
FISHES
RIVERS
STREAMS
SURFACE WATERS
VERTEBRATES
Salmonidae - John Day Reservoir (Wash. and Or.) - Mortality
130600* - Hydro Energy- Environmental Aspects