Reduced fitness of hatchery steelhead spawning in the natural environment is a pressing conservation concern for ESA-listed populations. Hatchery steelhead are typically reared for release as yearling smolts, rather than age-2 or age-3 that is more typical in nature. High growth rates needed to produce yearling smolts have been linked to maladaptive behavioral and physiological traits, and may constitute a primary mechanism leading to reduced fitness in hatchery fish.
This study has two primary objectives: 1) improve survival and reduce fitness loss in Columbia River steelhead smolts by minimizing unnatural selection on body size and other smolt characteristics, and 2) identify behavioral and physiological traits under selection through laboratory-scale research.
Berejikian, B.A., D.A. Larsen, P. Swanson, M.E. Moore, C.P. Tatara, W.L. Gale, C.R. Pasley, and B.R. Beckman. 2012. Development of natural growth regimes for hatchery-reared steelhead to reduce residualism, fitness loss, and negative ecological interactions. Env. Biol. Fish. 94(1): 29-44.