White sturgeon Acipenser transmontanus, like many sturgeon species worldwide, have suffered declines in abundance and distribution. The subpopulation of white sturgeon in the upper Columbia River above Grand Coulee Dam is classified as Critically Endangered (CE) by the IUCN and listed as endangered under the Canadian Species At Risk Act (SARA) due to persistent recruitment failure. Recruitment failure in the upper Columbia River between Grand Coulee and Hugh Keenleyside dams (the Transboundary Reach) white sturgeon population was first documented during studies conducted in the early 1990’s in the Canadian portion of the Reach (the Keenleyside Reach). Similar results were obtained in 1998 in the Washington portion of the Reach (the Roosevelt Reach). In response to increasing concerns over the threat of extinction, the Upper Columbia White Sturgeon Recovery Initiative (UCWSRI) was formed in 2000. The UCWSRI is an international organization with members from state, provincial, and federal fisheries agencies, Canadian First Nations, U.S. Tribes, and industry stakeholders in British Columbia and Washington State. The Initiative produced an Upper Columbia White Sturgeon Recovery Plan (UCWSRP) that is compatible with the ESA and SARA legislation. The goal of the UCWSRI, as defined in the UCWSRP, “is to ensure the persistence and viability of naturally reproducing populations of white sturgeon in the upper Columbia River and restore opportunities for beneficial use if feasible.”

The White Sturgeon Enhancement Project (WSEP) is a new project that was identified in the 2008 Fish Accords Memorandum of Agreement between the Colville Confederated Tribes (CCT) and the FCRPS Action Agencies. The project is intended to complement the existing recovery effort by addressing factors limiting recruitment of white sturgeon in the Transboundary Reach. This will be achieved by implementing the UCWSRP in direct coordination with the UCWSRI partners and Lake Roosevelt Co-Managers. Thus, the project goal is that of the UCRWSRI (above). The project specific objectives are consistent with the short- and medium-term objectives in the UCWSRP. The CCT WSEP objectives are to 1) monitor the status and trend of the Transboundary Reach white sturgeon population, and 2) identify factors limiting natural recruitment of white sturgeon in the Transboundary Reach.

Objective 1 - Monitor Population Status
Objective 1 is consistent with the UCWSRP short-term objective to assess the population status of white sturgeon in the Transboundary Reach. Population status and trend monitoring and associated database management are considered core components of the recovery effort. In 2013, the CCT, under this project, will have a support the population monitoring (supply a boat and crew) that will be led by the Spokane Tribe’s Lake Roosevelt Sturgeon Recovery Project (1995-027-00) in Washington and BC Hydro in British Columbia. Population monitoring will consist of setline stock assessment surveys to estimate abundance, growth, and condition, as well as fall sub-yearling gill net surveys to monitor for natural recruitment.

The historic, current, and future work related to Transboundary Reach white sturgeon has generated a substantial amount of data. There is a need for an integrated UCWSRI relational database management system that encompasses data collected by all of the UCWSRI partners to assist with research, monitoring, and management activities. In 2013, the CCT WSEP will subcontract and lead (i.e. request for proposal [RFP] development, contracting, facilitation) the development and maintenance of the UCWSRI database management system. The UCWSRI database could form the framework for a Columbia Basin White Sturgeon Data Management System such as that developed for pallid and shovelnose S. platorynchus sturgeon activities in the Missouri River system – the Sturgeon Information Management System (SIMS).

Objective 2 - Identify Factors Limiting Recruitment
Objective 2 is a component of the Upper Columbia White Sturgeon Recovery Initiative's Recovery Plan medium-term objective to determine survival limitations (bottlenecks) for remaining supportable populations and establish feasible response measures. The bulk of sturgeon larvae produced in any given year emerge from the substrate to begin feeding in the upper Roosevelt Reach (river-reservoir transition zone) in July. The timing of emergence generally coincides with rapidly declining river discharge and reservoir refill, which are factors that collectively may limit downstream dispersal. Sampling efforts to date confirm larvae are not found downstream of the transition zone. Conditions in the transition zone are apparently not conducive to survival as evidenced by lack of subyearling captures during fall gill net surveys. However, limited recruitment does occur in years, such as 1997, when very high river discharge (>5,663 m3 s-1) coincides with emergence of first feeding larvae suggesting dispersal may be a primary mechanism influencing survival. This suggests that suitable rearing habitat may exist in areas downstream from the river-reservoir interface in most water years.

In order to evaluate the larval transport/habitat mis-match hypothesis, the CCT and subcontractors will conduct hydrographic surveys of the upper Roosevelt Reach to characterize bathymetry and substrate typology in 2013. The habitat characterization results will form the foundation for future habitat modeling work to be completed under this project.

In addition to habitat modeling exercises, we will investigate the larval transport/habitat mis-match hypothesis empirically by analyzing the results of paired larval release experiments to compare relative survival to fall subyearling age between release locations. This work will be conducted assuming the CCT can obtain non-Federal funds to purchase and mark the larval sturgeon. If non-Federal funding is secured, experimental fish will be released into areas where naturally produced fish are known to be present each year (China Bend) and into areas further downstream (upper reservoir) where sampling efforts to date have indicated larvae are absent. The relative survival of release groups at subyearling and yearling ages will be evaluated from catch in fall gill net surveys.