Post-spawning Life History Diversity in Reconditioned Female Clearwater River Steelhead Trout (Oncorhynchus mykiss) Kelts Assessed Using Plasma Estradiol-17β
Steelhead trout (Oncorhynchus mykiss) are an important anadromous salmonid of conservation concern in Idaho’s Clearwater River, where populations are in decline. Post-spawn female steelhead trout (kelts) are reconditioned as a recovery tool in the Columbia River Basin. Reconditioning capitalizes on iteroparity, the ability to repeat spawn, and natural selection that occurs prior to initial spawning. Wild kelts are captured, fed, and released to spawn again naturally in the river without returning to the ocean. Hatchery-origin kelts are reconditioned as a research model. After maiden spawning, kelts may spawn again either after 1 year (consecutive spawner) or after 2 years (skip spawner). Females on the consecutive spawning trajectory (rematuring) can be distinguished from those on the skipping trajectory (non-rematuring) by elevated plasma estradiol-17β (E2) levels 6 months prior to spawning.
Jenkins, L., A. Pierce, N. Graham, L. Medeiros, S. Everett, D. Hatch, and J. Nagler. 2017. Post-spawning life history diversity in reconditioned female clearwater river steelhead trout (Oncorhynchus mykiss) kelts assessed using plasma estradiol-17β. 18th International Congress of Comparative Endocrinology, June 4-9, 2017. Banff National Park, Alberta, Canada.