The Federal Columbia River Power Supply (FCRPS) Biological Opinion (BiOp) calls for studies that estimate ecological and genetic impacts of hatchery fish on wild populations, and evaluate the effectiveness of hatchery supplementation measures to reduce potentially harmful effects of artificial production to aid recovery through hatchery reform. The FCRPS BiOp further explicitly calls for studies that examine the appropriate role of supplementation and the relationship between supplementation and habitat actions in salmon recovery. A basic premise of supplementation is that artificially produced fish will help develop self-sustaining spawning populations both by increasing current natural production and reestablishing populations in underutilized and recovered habitats.

One hatchery reform measure that has been incorporated into many supplementation programs throughout the Columbia River Basin is the use of satellite acclimation facilities to repopulate underutilized habitat. However, the efficacy of these facilities in re-establishing naturally spawning populations and minimizing negative interactions between wild spawners and supplemented fish has not been established. Our studies have involved comprehensive carcass and redd mapping surveys and radio telemetry to examine the role of acclimation sites in homing and spawning of spring Chinook salmon released as part of the Yakima/Klickitat Fisheries Project (YKFP) supplementation program. In addition, we are examining the complex linkages between habitat quality and spawning site selection in supplemented Columbia River populations. These studies involve mapping and assessing habitat distribution and quality relative to supplementation rearing and release facilities, and coupling these findings to ongoing analysis of homing and spawning patterns. Our results have provided unique insights into the process of homing, straying, and spawning site selection, interactions and success of hatchery and wild spawners, and the efficacy of supplementation and acclimation sites in salmon recovery.

These studies will help identify appropriate locations for recovery-related supplementation rearing and release facilities (acclimation sites), and ultimately allow us to develop scenario models predicting the spatial distribution of spawning relative to proposed supplementation facilities and available habitat (including future habitat restoration sites). The work is being conducted by Northwest Fisheries Science Center (NWFSC) scientists collaborating with the University of Washington, Yakima Nation, U.S. Geological Survey (USGS), and the Washington Department of Fish and Wildlife (WDFW). Products for this project include annual reports, peer-reviewed publications, presentation of results at local and national meetings, and consultation with the Northwest Regional Office (NWR) and supplementation managers. Comprehensive GIS data of Yakima River Spring Chinook spawners.