Review of potential interactions between stocked rainbow trout and listed Snake River sockeye salmon in Pettit Lake Idaho
The objective of this study was to determine if hatchery rainbow trout compete with or prey on juvenile Snake River sockeye salmon Oncorhynchus nerka in Pettit Lake, Idaho. In 1995, a total of 8,570 age-0 sockeye and 4,000 hatchery rainbow trout were released in Pettit Lake. After releasing the fish, gillnets were set in the pelagic and littoral zones to collected diet and spatial distribution data. Interactions were assessed monthly from June 1995 through March 1996. Competition for food was discounted based on extremely low diet overlap results observed throughout the sample period. Conversely, predation interactions were more significant. A total of 119 rainbow trout stomachs were analyzed, two contained O. nerka. The predation was limited to one sample period, but when extrapolated to the whole rainbow trout populations results in significant losses. Total consumption of O. nerka by rainbow trout ranged from an estimated 10 to 23% of initial stocking numbers. Predation results contradict earlier findings that stocked rainbow trout do not prey on wild kokanee or sockeye in the Sawtooth Lakes. The contradiction may be explained by a combination of poorly adapted hatchery sockeye and a littoral release site that forced spatial overlap that was not occurring in the wild populations. Releasing sockeye in the pelagic zone may have reduced or eliminated predation losses to rainbow trout.
- Research Organization:
- Shoshone-Bannock Tribal Fisheries Dept., Fort Hall Reservation, ID (United States)
- OSTI ID:
- 405699
- Report Number(s):
- DOE/BP/22548-4; ON: DE96014750; TRN: 97:000651
- Resource Relation:
- Other Information: PBD: May 1996; Related Information: Is Part Of Snake River Sockeye salmon habitat and limnological research. Annual report 1995; Teuscher, D.; Taki, D.; PB: 151 p.
- Country of Publication:
- United States
- Language:
- English
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