Kelt Reconditioning: A Research Project to Enhance Iteroparity in Columbia Basin Steelhead (Oncorhynchus mykiss), 2001 Annual Report.

Technical Report · Sun Dec 01 00:00:00 EST 2002

DOI:https://doi.org/10.2172/902988· OSTI ID:902988

Hatch, Douglas R.

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 artificially and in some cases 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 address recovery, we captured wild emigrating steelhead kelts from the Yakima River and tested reconditioning and the effects of several diet formulations on its success at Prosser Hatchery on the Yakama Reservation. Steelhead kelts from the Yakima River were collected at the Chandler Juvenile Evaluation Facility (CJEF, located at Yakima River kilometer 48) from 12 March to 5 July 2001. Kelts were reconditioned in circular tanks and fed a mixed diet of starter paste, adult sized trout pellets, and freeze-dried krill. Formalin was used to control outbreaks of fungus and we tested the use of Ivermectin{trademark}to control internal parasites (e.g., Salmincola spp.). Surviving specimens were released for natural spawning in two groups on 15 November 2001 and 18 January 2002. Overall success of the reconditioning process was based on the proportion of fish that survived in captivity, gained weight, and the number of fish that successfully underwent gonadal recrudescence. Many of the reconditioned kelts were radio tagged to assess their spawning migration behavior and success following release from Prosser Hatchery. In total, 551 kelts were collected for reconditioning at Prosser Hatchery. Captive specimens represented 18.7% (551 of 2,942) of the entire 2000-2001Yakima River wild steelhead population, based on fish ladder counts at Prosser Dam. At the conclusion of the experiments (208-323 days from capture), 108 fish (19.6%) had survived and were released to spawn in the wild. Ultrasound examination--to determine sex and reproductive development--determined that 100 (94.3%) of 106 sex-identified specimens were female and we estimated that 96% of the reconditioned releases gained weight and developed mature gonads. Nearly one quarter (24.3%) of all reconditioned kelts survived for the duration of the experiment. 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 type preferences, condition, and rearing environments were obtained during this research endeavor. Although higher survival rates would have been desirable, the authors were encouraged by the positive results of this innovative project. Nearly 20% of the kelts collected were successfully reconditioned, and radio telemetry allowed us to track some of these fish to the spawning grounds and to obtain documentation of successful redd construction. 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.
• Sponsoring Organization: United States. Bonneville Power Administration.
• DOE Contract Number: 00004185
• OSTI ID: 902988
• Report Number(s): DOE/BP-00004185-2; R&D Project: 200001700; TRN: US200720%%335
• Country of Publication: United States
• Language: English

Related Subjects

13 HYDRO ENERGY
54 ENVIRONMENTAL SCIENCES
ADULTS
COLUMBIA RIVER
DOCUMENTATION
ENDANGERED SPECIES
FEEDING
FEMALES
FISH PASSAGE FACILITIES
FOOD
FORMALDEHYDE
GONADS
JUVENILES
PARASITES
PELLETS
REARING
RIVERS
SALMON
TANKS
TELEMETRY
TROUT
Steelhead (Fish) - Spawning - Washington (State) - Yakima River Watershed