Spring Chinook Salmon Interactions Indices and Residual/Precocial Monitoring in the Upper Yakima Basin, 1998 Annual Report.
- Washington Department of Fish and Wildlife, Olympia, WA
Select ecological interactions and spring chinook salmon residual/precocial abundance were monitored in 1998 as part of the Yakima/Klickitat Fisheries Project's supplementation monitoring program. Monitoring these variables is part of an effort to help evaluate the factors that contribute to, or limit supplementation success. The ecological interactions that were monitored were prey consumption, competition for food, and competition for space. The abundance of spring chinook salmon life-history forms that have the potential to be influenced by supplementation and that have important ecological and genetic roles were monitored (residuals and precocials). Residual spring chinook salmon do not migrate to the ocean during the normal emigration period and continue to rear in freshwater. Precocials are those salmon that precocially mature in freshwater. The purpose of sampling during 1998 was to collect baseline data one year prior to the release of hatchery spring chinook salmon which occurred during the spring of 1999. All sampling that the authors report on here was conducted in upper Yakima River during summer and fall 1998. The stomach fullness of juvenile spring chinook salmon during the summer and fall averaged 12%. The food competition index suggested that mountain whitefish (0.59), rainbow trout (0.55), and redside shiner (0.55) were competing for food with spring chinook salmon. The space competition index suggested that rainbow trout (0.31) and redside shiner (0.39) were competing for space with spring chinook salmon but mountain whitefish (0.05) were not. Age-0 spring chinook salmon selected a fairly narrow range of microhabitat parameters in the summer and fall relative to what was available. Mean focal depths and velocities for age 0 spring chinook salmon during the summer were 0.5 m {+-} 0.2 m and 0.26 m/s {+-} 0.19 m/s, and during the fall 0.5 m {+-} 0.2 m and 0.24 m/s {+-} 0.18 m/s. Among potential competitors, age 1+ rainbow trout exhibited the greatest degree of microhabitat overlap with spring chinook salmon. Abundance of naturally occurring spring chinook salmon residuals (age 1+ during the summer) was low (< 0.007/m), representing less than 2% of the naturally produced spring chinook salmon (age 0+ and age 1+ during the summer). Abundance of naturally occurring spring chinook salmon that complete their life cycle in freshwater was high relative to anadromous adults. The authors observed an average of 9.5 precocially mature spring chinook salmon on redds with anadromous adults. In addition, 87% of the redds with anadromous adults present also had precocial males attending. All findings in this report should be considered preliminary and subject to further revision as more data and analytical results become available.
- Research Organization:
- Bonneville Power Administration, Portland, OR (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- 1995BI64878
- OSTI ID:
- 761683
- Report Number(s):
- DOE/BP-64878-4; R&D Project: 199506409; TRN: US0004636
- Resource Relation:
- Other Information: PBD: 1 Dec 1999
- Country of Publication:
- United States
- Language:
- English
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