Characterize and Quantify Residual Steelhead in the Clearwater River, Idaho, 2000 Annual Report.
- US Fish and Wildlife Service, Idaho Fishery Resource Office, Ahsahka, ID
We tagged 4,507 hatchery steelhead from Dworshak National Fish Hatchery (NFH), with Passive Integrated Transponder (PIT) tags to evaluate factors contributing to residualism. Steelhead lengths from typical growth ponds (System I) averaged 7mm less than those in faster growth ponds (System II) and travel times were 2 days faster. Steelhead were released into Clear Creek, South Fork Clearwater River, and from Dworshak NFH, and detection rates were 54.8%, 60.0% and 58.8%, respectively. The mean detection rates of steelhead analyzed by rearing system were, 51.5%, 59.8%, and 61.8% for System III, System I, and System II, respectively. We PIT tagged an additional 1,302 hatchery steelhead in the North Fork and mainstem Clearwater rivers between April 10 and August 28. Only 73 of these PIT-tagged steelhead were detected at a downstream dam and none were detected after June 14. In the 4 tributaries sampled, 77 steelhead were PIT tagged and released, 35.1% of which were detected emigrating downstream. Steelhead which were sacrificed for coded-wire tag information were also checked for sexual maturity. A total of 302 coded-wire tags were recovered; 87 from the Clearwater River, 119 from the North Fork Clearwater River, 80 from the Dworshak NFH adult return ladder, and 77 from the 4 tributaries. The precocious rate in males was 83.3% to 1.5% in females and the gender ratio was 79.8% males to 20.2% females. Although sample sizes were small, we were able to verify that at least one residual steelhead survived the winter to persist in the Clearwater River. Based on this years data, the majority of steelhead, which do not emigrate during the first couple of weeks after release, are unlikely to emigrate. Final analysis will also include influences of water flow and temperature in emigration success. This information needs to be compared over several years (at least three) for meaningful analysis.
- Research Organization:
- US Fish and Wildlife Service
- Sponsoring Organization:
- United States. Bonneville Power Administration.
- DOE Contract Number:
- 00004665
- OSTI ID:
- 834375
- Report Number(s):
- DOE/BP-00004665-2; R&D Project: 199901800; TRN: US200516%%1336
- Resource Relation:
- Other Information: PBD: 1 May 2001
- Country of Publication:
- United States
- Language:
- English
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