Recruitment failure in the white sturgeon population occupying the Transboundary Reach of the upper Columbia River (Grand Coulee Dam, WA, U.S.A to Hugh Keenleyside Dam, British Columbia, Canada) was first documented during studies conducted in the early 1990’s in the Canadian portion of the Reach (referred to as the Keenleyside Reach) (Hildebrand and English 1991; R.L.&L. 1994; Hildebrand et al. 1999).  These studies determined that juvenile age-classes (under ten years of age) were lacking within the population.  Similar results were obtained in the U.S. section of the Reach (referred to as the Roosevelt Reach) in 1998 (Devore et al. 2000; USGS; Kappenman et al. 2000).  Recent sturgeon studies in the Keenleyside Reach (Golder Associates Ltd. 2003, 2005a; Arndt 2003) and Roosevelt Reach (Lee and Underwood 2002; Lee and Pavlik 2003; Howell and McLellan 2005, 2006, in prep.) show a continuation of poor recruitment through failure to catch large numbers of juvenile sturgeon representing multiple year classes.

The onset of the recruitment decline in the Transboundary Reach white sturgeon population coincided with the construction of Columbia River mainstem dams in Canada commencing with Hugh L. Keenleyside (HLK; 1968), and followed by Mica (1976) and Revelstoke (1984).  Reproductive failure of this population therefore appears directly related to the effects of river regulation (R.L. & L. 1994).  The exact mechanisms limiting recruitment are unknown but are currently the focus of ongoing studies in the Transboundary Reach.

The Upper Columbia White Sturgeon Recovery Initiative (UCWSRI), an international organization with members from state, provincial, and federal fisheries agencies and First Nations tribes in British Columbia and Washington State produced the Upper Columbia White Sturgeon Recovery Plan (UCWSRP) in 2002 (UCWSRI 2002).  The UCWSRP outlined various short, mid and long-term measures required to prevent the extinction of white sturgeon populations in the Columbia River above Grand Coulee Dam (UCWSRI 2002).  Study efforts in 2007 will focus on continuing to examine limiting factors for sturgeon in the Transboundary Reach.  

FY2007 Work:
Egg Sampling:  We will assess timing and duration of spawning in the Roosevelt Reach, estimate numbers of spawning events, quantify physical habitat characteristics at spawning sites and verify white sturgeon spawning at the Northport spawning location.  Plankton drift net sampling will also be conducted below Waneta and Northport spawning areas to confirm the emergence of free-embryos/larvae and to investigate their downstream dispersal.

Larval Work:  Despite documented spawning and hatch success in previous years, no YOY sturgeons were captured during fall gill netting activities, indicating recruitment failure may not be due to limited numbers of spawners, poor gamete quality, or lack of suitable habitat for spawning and incubation of eggs.  This indicates that a bottleneck occurs sometime between the onset of exogenous feeding and recruitment to YOY.  Larvae examined for diet items at the stage of initiation of exogenous feeding exhibited no food items in their digestive track, suggesting that suitable forage is limited and larvae may be starving.  

In 2007, we plan to investigate the ecology and fate/survival of white sturgeon posthatch life stages.  We plan to define the extent of free embryo dispersal during post hatch dispersal phase and assess physical and chemical water and sediment quality parameters near the egg substrate and larval sampling areas to identify potentially adverse conditions for egg survival.  We also plan to conduct stage larval collections to identify substrate habitats utilized during the yolk absorption hiding phase based on catch distributions found in posthatch life stage assessments and to explore starvation as a limiting factor by examining stomach contents of larvae at the stage of exogenous feeding.

Juvenile Assessments:  Previous juvenile sturgeon studies in the transboundary reach were conducted to determine population estimates, and to assess distribution, condition, growth, age, diet, behavior, and survival of wild and hatchery origin juvenile sturgeon.  In 2007, we plan to continue juvenile white sturgeon stock assessment sampling in the U.S. portion of the upper Columbia River to detect natural recruitment as well as evaluate the conservation aquaculture program releases.  

Adult Assessments:  Previously, adult stock assessments were conducted in the upper portion of the reservoir only because studies indicated the vast majority of sturgeons were concentrated in that area and funding was limited for extensive reservoir wide surveys.  In 2007, we plan to begin assessing the lower third of the reservoir to more completely assess transboundary adult populations and movement from the upper reaches to the lower reaches of the reservoir.  Using 2007 and previously collected data, we will describe population size structure, condition, growth, sex, and maturity for the population in the Roosevelt Reach.

Telemetry Monitoring:  Telemetry investigations will be performed to identify spawning areas in the U.S., as well as to identify important seasonal habitats and patterns of sturgeon movement in the Transboundary Reach as part of the cooperative UCWSRI Transboundary Telemetry and Data Management Project.

Substrate Mapping:  In 2007, we plan to map riverbed substrates where larval white sturgeon settle and rear.  Assessments of the abundance and distribution of benthic invertebrates in larval white sturgeon settling areas will require knowledge of the distribution of riverbed substrates to develop complete benthic invertebrate sampling strategies.  We plan to use side scan sonar and differentially corrected GPS to develop spatially accurate maps of sediment distribution where larval and juvenile white sturgeon are known to rear and where drifting larvae would be expected to settle.

Benthic Invertebrates:  In 2007, we plan to implement a pilot survey to assess gear types and level of effort required to assess benthic invertebrates in the egg and larval sampling areas.  Based on this and the substrate mapping data collected, we plan to design and implement a complete invertebrate sampling protocol.

Broodstock:  Under the current operations of the UCWSRI conservation aquaculture program, sturgeon eggs will be collected from U.S. and British Columbia wild broodstock (ripe adults) which are transferred to the Sherman Creek Hatchery (SCH) in Kettle Falls, WA and the Kootenay Sturgeon Hatchery (KSH) in Wardner, British Columbia, respectively.  Ripe adults will be held until final maturation and then spawned.  The resulting fertilized eggs will be incubated at Columbia Basin Hatchery, Moses Lake, WA, and KSH in British Columbia until hatch and the larvae will be reared to juveniles for approximately nine months.  The yearlings are then scute marked, PIT tagged, and released into the Columbia River.  In 2007, the U.S. partners plan to expand the number of family groups produced in the U.S. aquaculture program from two to three.

Public Outreach and Project Coordination:  We also plan to continue public outreach and coordination efforts through the project.  In May, 2007 we will invite school kids to Lake Roosevelt to learn about sturgeon during Student Discovery Week and we plan to reach out at events (such as the Lake Roosevelt Forum Conference) to inform the public about the decline of the Lake Roosevelt/Upper Columbia River white sturgeon.  The project will also coordinate amongst project participants and the UCWSRI to integrate white sturgeon research efforts in the upper Columbia River, and the broader Columbia River Basin white sturgeon research community.