Bonneville Power Administration Annual Reports (Growth Modulation in Chinook Salmon Supplementation)

Reasonable and Prudent Alternative (RPA) 63.2 of FCRPS Biological Opinion calls for determining the effects of implementing hatchery reforms on salmon and steelhead populations and RPA 65.2 is focused on estimating fall Chinook hatchery program effects on productivity.

A major focus of current actions under Northwest Power and Conservation Council (NWPCC 2004) and Bonneville Power Administration (BPA) programs is the support of 12 supplementation programs to assist in recovery of 8 ESUs of Chinook salmon and steelhead trout listed as threatened or endangered under the ESA. A significant concern for these programs is that they release fish that are ecologically, genetically, and phenotypically similar to their wild cohorts. In response to this concern, a number of rearing guidelines for supplementation programs have been made in the Artificial Production Review and Evaluation report (APRE). Preliminary data suggests that yearling hatchery releases of upriver bright (URB) fall Chinook salmon (currently a key part of supplementation programs for ESA listed Snake River URB fall Chinook salmon) results in a high proportion of early male maturation. This represents a loss of production, a threat to the maintenance of the genetic integrity of the naturally spawning population. Documented evidence also suggests that yearling releases of URB fall Chinook salmon result in a high proportion of early maturing males in the Yakima and Umatilla Basins. Counts of age-2 upstream migrants at Three Mile Falls Dam on the Umatilla River suggest that significant minijack production was evident at the initiation of yearling fall Chinook salmon releases in the Umatilla River (Umatilla Fall Chinook HGMP).

While potentially ubiquitous and common, little effort has been put forth to either enumerate or evaluate minijack production; thus, the problem is largely (and conveniently) ignored.This project has three central objectives:

1) Improve survival and reduce fitness loss in Columbia River URB Fall Chinook salmon. We will determine rates of minijack production (through measurement of plasma 11-ketotestosterone levels) and associated physiological development including growth, whole body lipid, plasma IGF-1 (endocrine index of growth physiology) and Na+/K+-ATPase activity (enzyme indicator of smolt development) in Umatilla stock URB Fall Chinook salmon.

2) Refine rearing protocols to reduce minijack rates and optimize smolt development in URB Fall Chinook salmon. We will conduct a laboratory scale experiment at the Northwest Fisheries Science Center (NWFSC), Seattle exploring the effects of alterations in emergence timing and growth rate (via ration manipulation) on life-history development and associated physiology in Umatilla River URB Fall Chinook.

3) Continue long-term minijack monitoring in Spring Chinook salmon from the Yakima River Supplementation Program. We will continue to collect data for our long-term monitoring effort at the Yakima River Cle Elum Supplementation and Research Facility (CESRF) documenting size, gender proportions and minijack rates and threshold size for early male maturation of the Supplemented Natural (SN) line and Hatchery Control (HH) Line of this program. Annual Report