The Idaho Supplementation Studies (ISS) is a Clearwater River and Salmon River sub-basin wide cooperative research project partitioned among four resource management entities including the Idaho Department of Fish and Game, Nez Perce Tribe, Shoshone-Bannock Tribe, and the U.S. Fish and Wildlife Service. The Idaho Department of Fish and Game functions acts as the lead agency with respect to project development, coordination, and implementation. The project encompasses 30 streams throughout Idaho. Sixteen streams have received supplementation treatments and 14 are un-supplemented controls. Each agency is individually contracted through Bonneville Power Administration, but data collection and reporting duties are administered through a joint statement of work, which helps ensure that consistent protocols are used by each agency. This Statement of Work for contract year 2007 (Jan 1 - Dec 31, 2007) includes synthesis of research activities and tasks to be completed by all cooperating agencies.

The goals of the Idaho Supplementation Studies Project are to 1) assess the effectiveness of localized hatchery broodstocks to increase the size of naturally spawning spring and summer Chinook salmon populations in the Salmon and Clearwater river drainages, and 2) evaluate the long-term genetic and ecological impacts of supplementation on these populations.  Specific objectives of the program include monitoring and evaluating the effects of supplementation on natural production in Chinook salmon populations, monitoring and evaluating changes in productivity in these populations relative to supplementation, and developing recommendations for the use of supplementation.  

The ISS study uses a multi-phased approach to evaluate supplementation. In Phase I, local adult returns were collected to develop supplementation broodstock. Phase II (treatment phase) used the returning supplementation adults to augment natural reproduction in treatment streams. In Phase III, or evaluation phase, supplementation treatments will be terminated, but we will continue to monitor production and productivity in both treatment and control populations for one Chinook salmon generation (i.e., five years). Determining population response after supplementation ceases will provide valuable insight into the long-term effects of supplementation.  Currently, the project is transitioning between Phase II and III.  In 2007 the last supplementation adults (the five-year-old component from our brood year 2002 juvenile releases) will return representing the program’s final supplementation treatment.