Feeding Activity, Rate of Consumption, Daily Ration and Prey Selection of Major Predators in the John Day Pool : 1983, Annual Report.
This report summarizes activities in 1983, the second of a five year study to determine the extent of predation by resident populations of native and introduced fishes on juvenile salmonids in John Day Reservoir. As in 1982, catches of northern squawfish (Ptychocheilus oregonensis) were highest in areas adjacent to dams; percent by weight of juvenile salmonids in the diet was up to 89.7% higher in these areas. Catches of walleyes (Stizostedion vitreum vitreum) were greatest outside restricted zones (700 to 900 m above and below the dams) in spring of both 1982 and 1983. Percent by weight of juvenile salmonids in walleyes collected in 1983 was generally higher at McNary tailrace and lower at Irrigon and John Day tailrace than in 1982. Smallmouth bass (Micropterus dolomieui) was the most common species collected and contained few salmonids in 1983. Results of the diet analysis for channel catfish (Ictalurus punctatus) varied substantially between 1982 and 1983 as a result of eliminating the John Day River sampling transect and increasing sampling effort at McNary tailrace, Irrigon, and John Day tailrace. The beach seine and boat electroshocker were effective gears for evaluating prey abundance. Data obtained to estimate relationships between fork length of juvenile chinook salmon (Oncorhynchus tshawytscha) and other body or bone measurements indicated that body length predicted fork length best, followed by cleithrum, dentary, and opercle measurements. Digestion over time was estimated for 162 northern squawfish fed juvenile salmonids at temperatures ranging from 10 to 20 C. 1 ref., 7 figs., 31 tabs.
- Research Organization:
- Fish and Wildlife Service, Seattle, WA (USA). Seattle National Fishery Research Center
- DOE Contract Number:
- AI79-82BP34796
- OSTI ID:
- 5447579
- Report Number(s):
- DOE/BP-382; ON: DE85015780
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted; Related Information: Spine title: Prey selection of major predators.
- 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, 1986 : Annual Report.
Feeding Activity, Rate of Consumption, Daily Ration and Prey Selection of Major Predators in John Day Reservoir, 1984 : Annual Report.
Related Subjects
SALMON
PREDATOR-PREY INTERACTIONS
BASELINE ECOLOGY
BEHAVIOR
FISHES
HABITAT
OREGON
SAMPLING
WATER RESERVOIRS
ANADROMOUS FISHES
ANIMALS
AQUATIC ORGANISMS
ECOLOGY
FEDERAL REGION X
NORTH AMERICA
SURFACE WATERS
USA
VERTEBRATES
Fishes - Food - Columbia River
Predation (Biology)
520100* - Environment
Aquatic- Basic Studies- (-1989)