Kelt Reconditioning: A Research Project to Enhance Iteroparity in Columbia Basin Steelhead (Oncorhynchus mykiss), 2002 Annual Report.
- Columbia River Inter-Trial Fish Commission, Portland, OR
- Yakama Nation, Toppenish, WA
Repeat spawning is a life history strategy that is expressed by some species from the family Salmonidae. Rates of repeat spawning for post-development Columbia River steelhead Oncorhynchus mykiss populations range from 1.6 to 17%. It is expected that currently observed iteroparity rates for wild steelhead in the Basin are severely depressed due to development and operation of the hydropower system and various additional anthropogenic factors. Increasing the natural expression of historical repeat spawning rates using fish culturing means could be a viable technique to assist the recovery of depressed steelhead populations. Reconditioning is the process of culturing post-spawned fish (kelts) in a captive environment until they are able to reinitiate feeding, growth, and again develop mature gonads. Kelt reconditioning techniques were initially developed for Atlantic salmon Salmo salar and sea-trout S. trutta. The recent Endangered Species Act listing of many Columbia Basin steelhead populations has prompted interest in developing reconditioning methods for wild steelhead populations within the Basin. To test kelt steelhead reconditioning as a potential recovery tool, we captured wild emigrating steelhead kelts from the Yakima River and evaluated reconditioning (short and long-term) success and diet formulations at Prosser Hatchery on the Yakima River. Steelhead kelts from the Yakima River were collected at the Chandler Juvenile Evaluation Facility (CJEF, located at Yakima River kilometer 48) from March 12 to June 13, 2002. In total, 899 kelts were collected for reconditioning at Prosser Hatchery. Captive specimens represented 19.8% (899 of 4,525) of the entire 2001-2002 Yakima River wild steelhead population, based on fish ladder counts at Prosser Dam. Kelts were reconditioned in circular tanks and were fed freeze-dried krill, Moore-Clark pellets, altered Moore-Clark pellets (soaked in krill extract and dyed), or a combination of the altered Moore-Clark/unaltered Moore-Clark pellets. Formalin was used to prevent outbreaks of fungus and we also intubated the fish that were collected with Ivermectin{trademark} to control internal parasites (e.g., Salmincola spp.). Captured kelts were separated into two experimental groups: short-term and long-term reconditioning. Success indicators for the short-term experiment include the proportion of fish that survived the reconditioning process and the proportion of fish that initiated a feeding response. Short-term kelts were then subsequently split into two groups for either 1 or 2-month reconditioning. Surviving specimens were released for natural spawning in two groups, corresponding with reconditioning duration, with releases on May 20/28, 2002. Survival rates for both short-term experiments were high. Long-term reconditioned kelts were subsequently split into three groups that were given three different diet formulations and then released on December 10, 2002. Long-term success indicators include the proportion of fish that survived the reconditioning process and the proportion of surviving fish that successfully remature. A total of 60 reconditioned kelts were radio tagged to assess their spawning migration behavior and success following release from Prosser Hatchery and to evaluate in-season homing fidelity. As in previous years, the kelts reconditioned during this project will substantially bolster the number of repeat spawners in the Yakima River. Valuable knowledge regarding kelt husbandry, food preferences, condition, and rearing environments were obtained during this research endeavor. Although survival rates were higher in 2002, even higher survival rates would be desirable; overall the authors were encouraged by the positive results of this innovative project. Information collected during this feasibility study has been significantly incorporated into the experimental design for upcoming years of research, and is expected to continue to increase survival and successful expression of iteroparity.
- Research Organization:
- Columbia River Inter-Tribal Fish Commission. Yakama Nation.
- Sponsoring Organization:
- United States. Bonneville Power Administration.
- DOE Contract Number:
- 00004185
- OSTI ID:
- 902990
- Report Number(s):
- DOE/BP-00004185-3; R&D Project: 200001700; TRN: US200720%%336
- Country of Publication:
- United States
- Language:
- English
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