Effects of Captive Reconditioning and Post-Spawning Life History on Reproductive Performance in Female Steelhead (Oncorhynchus mykiss) Kelts

Post-spawn female steelhead (kelt) reconditioning is a recovery tool addressing endangered populations in the Snake River. Kelts are captured, fed, and released to spawn naturally. Kelt reconditioning capitalizes on iteroparity, the ability to repeat spawn, and natural selection that occurred prior to initial spawning. Reconditioned kelts may re-mature to spawn in one year (consecutive spawner) or in two years (skip spawner). Quantifying the benefit of kelt reconditioning requires comparing the reproductive performance of consecutive and skip spawning kelts to that of maiden spawners. Dworshak National Fish Hatchery origin steelhead, a model for native Clearwater River B-run steelhead, were spawned and reconditioned upon return to the Hatchery. Reproductive development was monitored and reproductive performance assessed. Plasma estradiol levels were elevated in re-maturing kelts in summer prior to spawning. 23% of surviving kelts spawned after one year of reconditioning. 100% of remaining kelts spawned the following year as skip spawners.  Fecundity and egg size were greater in kelts than maidens, but not different between consecutive and skip spawners. Results to date show fertilization success was not different between groups. Spawn date fidelity was greater in consecutives and length increase greater in skips.  Captive kelt reconditioning does not appear to compromise reproductive performance.