Development of a System-Wide Predator Control Program : Stepwise Implementation of a Predation Index, Predator Control Fisheries and Evaluation Plan in the Columbia River Basin, 1991 Annual Report.
We report our results from the first year of a basin-wide program to harvest northern squawfish in an effort to reduce mortality due to northern squawfish predation on juvenile salmonids during their emigration from natal streams to the ocean. Earlier work in the Columbia River basin suggested predation by northern squawfish on juvenile salmonids may account for most of the 10 to 20 percent mortality juvenile salmonids experience in each of eight Columbia and Snake river reservoirs. Modeling simulations based on work in John Day Reservoir from 1982 through 1988 indicated it is not necessary to eradicate northern squawfish to substantially reduce predation-caused mortality of juvenile salmonids. Instead, if northern squawfish were exploited at a 10 to 20 percent rate, reductions in their numbers and restructuring of their populations could reduce their predation on juvenile salmonids by 50 percent or more. Consequently, we designed and tested a sport reward hook-and-line fishery and a longline fishery in the John Day pool in 1990. Based on the successfulness of these limited efforts, we implemented three test fisheries on a multi-pool or system wide scale in 1991: a tribal longline fishery, a sport reward fishery, and a dam angling (hook-and-line) fishery. In addition, we examined several alternative harvest techniques to determine their potential for use in system-wide test fisheries. Evaluation of the success of the three test fisheries conducted in 1991 in achieving a 20 percent exploitation rate on northern squawfish, together with information regarding the economic, social, and legal feasibility of sustaining each fishery, is presented in Section II of this report.
- Research Organization:
- Oregon Department of Fish and Wildlife (ODFW)
- Sponsoring Organization:
- US Bonneville Power Administration
- DOE Contract Number:
- 1990BP07084
- OSTI ID:
- 862370
- Report Number(s):
- DOE/BP-07084-2; TRN: US200602%%483
- Country of Publication:
- United States
- Language:
- English
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