2007 Annual Report: Steelhead Kelt Reconditioning and Reproductive Success
Iteroparity, the ability to repeat spawn, is a natural life history strategy that is expressed by some species from the family Salmonidae. Current rates of observed steelhead iteroparity rates in the Columbia River Basin are severely depressed due to anthropogenic development, operation of the hydropower system and other factors. Artificial reconditioning, which 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, is evaluated in this study as method to restore depressed steelhead populations. To test the efficacy of steelhead kelt reconditioning as a management and recovery tool different scenarios were investigated ranging from very low intensity (collect and transport fish) to high intensity (collect and feed fish in captivity until rematuration). Examinations of gamete and progeny viability were performed for first-time spawners and reconditioned kelt steelhead. Further, a long-term field study is being implemented to evaluate the relative reproductive success of natural-origin, hatchery-origin, and reconditioned kelt steelhead to two streams. Parentage analysis is being performed on juvenile O. mykiss from the study streams using 16 microsatellite loci. Analysis of management scenarios indicated that no-term and short-term reconditioned kelts continue to perform well outmigrating to the ocean but returns from these groups have ranged from 0-12% during 2002-2007. Long-term reconditioning has rebounded to nearly 54% surviving to remature and release. The first successful year of kelt gamete and progeny analysis demonstrated that success fell within the normal range for steelhead gamete and juvenile development. Fertilization rates were lower when compared against the first time spawning but egg and juvenile survival was higher. This year marked the first documented evidence of a steelhead kelt successfully spawning in the wild, we discovered 3 juveniles that were of direct genetic lineage to a steelhead kelt that was released in 2006 at Omak Creek. The management exploration has discovered that river or ocean conditions may be inhibiting the ability of kelts to successfully return from the ocean after release. Secondly the success of long-term reconditioning may be tied to the quality of kelts that are returning from the ocean. The progeny and gamete and reproductive success data are both preliminary but both demonstrate that steelhead kelts have the ability to reproduce successfully and contribute viable offspring.
Branstetter, R., J. Stephenson, D.R. Hatch, J. Whiteaker, and S-Y. Hyun. 2008. 2007 Annual Report: Steelhead Kelt Reconditioning and Reproductive Success. Columbia River Inter-Tribal Fish Commission Technical Report #08-03, Portland, Oregon.
May 12th, 2008
CRITFC Technical Report