Long‐term evaluation of fitness and demographic effects of a Chinook Salmon supplementation program

• DOI: 10.1111/eva.12725
• Publication Date: 2018-10-21T09:36:21Z
• Authors: Ilana Janowitz‐Koch; Craig Rabe; Ryan Kinzer; Doug Nelson; Maureen A. Hess; Shawn R. Narum
• Keywords: Hatchery; Broodstock; Chinook wind; Natural population growth

Abstract While the goal of supplementation programs is to provide positive, population‐level effects for species conservation concern, these can also present an inherent fitness risk when captive‐born individuals are fully integrated into natural population. In order evaluate long‐term a program and estimate demographic phenotypic factors influencing threatened population Chinook Salmon ( Oncorhynchus tshawytscha ), we genotyped tissue samples spanning 19‐year period (1998–2016) generate pedigrees from adult fish returning Johnson Creek, Idaho, USA. We expanded upon previous estimates relative reproductive success (RRS) include grandparentage analyses used generalized linear models determine whether origin (hatchery or natural) traits (timing arrival spawning grounds, body length, age) significantly predicted (RS) across multiple years. Our results evidence that this with 100% natural‐origin broodstock provided boost (mean 4.56 times in first generation mean 2.52 second generation). Overall, nature, hatchery‐origin demonstrated trend toward lower RS compared p < 0.05). However, successfully spawned fish, they had similar by crosses (first‐generation hatchery cross RRS = 1.11 females, 1.13 males; second‐generation 1.03 1.08 males). origin, return year, length were significant predictors both males females 0.05), day was but not > These indicate reduce potential genetic adaptation captivity be effective at increasing abundance while limiting on wild populations.