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Scientific Report

Kelt Reconditioning: A Research Project to Enhance Iteroparity in Columbia Basin Steelhead (Oncorhynchus mykiss) – 2004 Annual Report

Abstract

Iteroparity, the ability to repeat spawn, 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 expression of historical repeat spawning rates using fish culturing methods could be a viable technique to assist the recovery of depressed steelhead populations, and could help reestablish this naturally occurring life history trait. Reconditioning is the process of culturing post-spawned fish (kelts) in a captive environment until they are able to reinitiate feeding, growth, and redevelop 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 River 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, wild emigrating steelhead kelts were placed into one of three study groups (direct capture and transport, short-term reconditioning, or long-term reconditioning. Steelhead kelts from the Yakima River were collected at the Chandler Juvenile Monitoring Facility (CJMF, located on the Yakima River at river kilometer 75.6) from 15 March to 21 June 2004. In total, 842 kelts were collected for reconditioning at Prosser Hatchery. Captive specimens represented 30.5% (842 of 2,755) of the entire 2003-2004 Yakima River wild steelhead population, based on fish ladder counts at Prosser Dam. All steelhead kelts were reconditioned in 20-foot circular tanks, and fed freeze-dried krill initially or for the duration of the experiment. All steelhead kelts received hw-wiegandt multi vit dietary supplement as a means to improve initial nutrition. Long-term steelhead kelts received Moore-Clark pellets to provide essential minerals and nutrients necessary for gonadal redevelopment. Oxytetracycline was administered to all reconditioned fish to boost immune system response following the stress of initial capture. To control parasitic infestations two methods were used, first, after initial capture an intubation of IvermectinTM was administered to control internal parasites (e.g., Salmincola spp.) next, a Formalin drip was used for the duration of reconditioning to prevent fungal outbreaks. Captured kelts were separated into three experimental groups: short-term reconditioning, long-term reconditioning, and direct transport and release. 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 reconditioned for 3 to 5 weeks. Surviving specimens were released for natural spawning on May 11, 2004. Survival-to-release was good for the short-term experiment, with a rate of 79.0%. Long-term steelhead kelts are currently being held for a 6-9 month period with a scheduled release in December 2004. Long-term success indicators include the proportion of fish that survived the reconditioning process and the proportion of surviving fish that successfully remature. Survival and rematuration for long-term kelts has not been determined and will be presented in the 2005 annual report. Direct transport and release kelts and short-term reconditioned kelts were radio or acoustic tagged to assess their travel time and migratory behaviors below Bonneville Dam. A total of 29 direct-transport and release kelts and 29 short-term reconditioned kelts received surgically implanted radio tags, and a total of 28 direct-transport/release and 26 short-term reconditioned fish received surgically implanted hydro acoustic tags. These tags will allow us to determine out-migration timing for adults as well as determine if reconditioning has any deleterious effects on migration behavior. Long-term reconditioned fish will have radio tags inserted gastrically to monitor migration to spawning grounds. 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 reconditioned for 3 to 5 weeks. Surviving specimens were released for natural spawning on May 11, 2004. Survival-to-release was good for the short-term experiment, with a rate of 79.0%. Long-term steelhead kelts are currently being held for a 6-9 month period with a scheduled release in December 2004. Long-term success indicators include the proportion of fish that survived the reconditioning process and the proportion of surviving fish that successfully remature. Survival and rematuration for long-term kelts has not been determined and will be presented in the 2005 annual report. Direct transport and release kelts and short-term reconditioned kelts were radio or acoustic tagged to assess their travel time and migratory behaviors below Bonneville Dam. A total of 29 direct-transport and release kelts and 29 short-term reconditioned kelts received surgically implanted radio tags, and a total of 28 direct-transport/release and 26 short-term reconditioned fish received surgically implanted hydro acoustic tags. These tags will allow us to determine out-migration timing for adults as well as determine if reconditioning has any deleterious effects on migration behavior. Long-term reconditioned fish will have radio tags inserted gastrically to monitor migration to spawning grounds. As in previous years, the kelts reconditioned during this project should substantially bolster the number of repeat spawners in the Yakima River. Valuable knowledge regarding kelt husbandry, condition, and rearing environments were obtained during this research endeavor. The authors were very pleased with the high survival rates. Information collected during this feasibility study will be incorporated into the experimental design for next year’s research, and is expected to continue to increase survival of long-term reconditioned fish and the successful expression of iteroparity.

Authors

Douglas R. Hatch, Ryan Branstetter, John Whiteaker, Joe Blodgett, Bill Bosch, David Fast, and Todd Newsome

Citation

Hatch, D., R. Branstetter, J. Whiteaker, J. Blodgett, B. Bosch, D. Fast, and T. Newsome. 2004. Kelt Reconditioning: A Research Project to Enhance Iteroparity in Columbia Basin Steelhead (Oncorhynchus mykiss) - 2004 Annual Report. Project No. 2000-017-00, BPA Report DOE/BP-00004185, 49 pages.

Date

Nov 1st, 2004

Report No.

04-08

Media Type

Inter-Agency Report

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