Background

Without effective intervention, the white sturgeon population appears to be headed for extinction in the Columbia River upstream from Grand Coulee Dam. Data indicates natural recruitment has been very limited and the majority of the population now consists of an aging cohort of adults whose numbers are steadily dwindling. Upper Columbia River white sturgeon are subject to a recovery plan initiated in Canada and completed with involvement by U.S. parties. This recovery plan identifies the lack of information on the actual numbers and limiting factors of white sturgeon in the U.S. portion of the Upper Columbia River as a critical uncertainty.

Extensive assessments have been completed in the Canadian portion of the transboundary reach of the Columbia River (R.L. & L 1994), but little sturgeon work has been conducted in U.S. portions of this reach.  In 1998, the Washington Departments of Fish and Wildlife and the Spokane Tribe of Indians sampled an aged white sturgeon population above Grand Coulee Dam, and confirmed that virtually no recruitment has occurred during the past 20-25 years. No young of year sturgeon were collected in 1998 by USGS trawling surveys above Grand Coulee Dam, although these same methods have collected YOY in other reservoirs throughout the lower Columbia and Snake Rivers. It remains unclear whether sturgeon in Canadian and U.S. waters of the transboundary reach are discrete subgroups and if recovery measures planned in Canada will be affected by and effective in U.S. waters.

As described in Section 10.4A of the 1994 FWP, concern has arisen over the declining status of native sturgeon populations throughout the Columbia River Basin. White sturgeon populations above Grand Coulee Dam were closed to harvest in 1996 due to increasing concerns over the apparent declining status of the population. Mitigative and/or restorative efforts have become necessary to maintain this particular white sturgeon stock, which possesses genetic traits different from other Columbia River stocks (Setter and Brannon 1992, Brannon et al 1987). Similar genetic differences and recruitment failure for the Kootenai River white sturgeon stock, led to listing as an endangered species in 1994.

Sturgeon populations are declining, in part, due to dam construction and hydropower operations, which result in habitat fragmentation and hydrograph reversal (Apperson and Anders 1991; Partridge 1983).  Dams block access between dispersed spawning and feeding areas. Numerous authors have noted the importance of high spring flows in sturgeon spawning and recruitment (Nilo et al. 1997; Auer 1996; Parsley 1991), and hydro-operations may be, in part, related to the lack of recruitment noted in the upper
Columbia River. Other factors may also play an important role in limiting recruitment of white sturgeon above Grand Coulee Dam, including food availability, predation of juveniles by walleye and other piscivores, and water/sediment quality issues related to zinc smelting operations in Canada and mining operations in the U.S.

During 2001-2002, this project assisted in the development of an Upper Columbia River White Sturgeon Recovery Plan (UCWSRP) that reviewed available information on sturgeon status and biology, identified objectives, strategies, and measures for sturgeon recovery, and outlined a coordinated effort on both sides of the border. The UCWSRP identifies critical uncertainties for sturgeon in the reach from Lake Roosevelt to Canada related population status, habitat suitability, limiting factors, and effective
management actions. This scope of work details a research and evaluation program for addressing some of these critical uncertainties.

Egg Sampling:  The upper Columbia River sturgeon population is currently threatened by a failure of natural recruitment.  It is unclear if recruitment has failed as a result of poor spawning conditions, poor rearing conditions, spawning stock limitation, or some combination of these factors.  Consistent spawning has been observed just north of the Canadian border at the mouth of the Pend Oreille River near Waneta but this spawning site does not appear to be contributing significant numbers of juveniles to the population.  Of six adult female sturgeon that were in late stages of maturity tagged in the U.S. in 2004, none moved to the spawning site in Canada.  The movements of these fish, the collection of larvae and an eggs near Northport, and observed adult activity near Northport during the spawning period, suggested it was possible that another spawning site existed in the U.S. near Northport.  Spawning in the Northport area was confirmed in 2005 using telemetry data to locate ripe adult fish and egg substrate sampling to collect eggs.

Prospects for sturgeon recovery through natural recruitment depend in part on the availability of suitable spawning habitat.  Identifying spawning areas also allows us to focus our efforts to study factors related to the recruitment failure, such as egg and larval predation, larval dispersal, larval habitat availability, and food availability for larvae.  We will use artificial spawning substrate mats to confirm the presence or absence of eggs at the Northport spawning sites to document the frequency of spawning events and determine the timing and duration of the spawning season.  Substrates will be placed in June and July and checked at two or four day intervals as long as temperatures remain suitable for spawning (<20oC) or tagged fish are present.  Eggs will be removed from substrates, preserved, and staged in the laboratory to determine age and spawning date.  

Larval Sampling:  In 2004 we conducted a pilot project to collect white sturgeon larvae in the U.S. portion of the transboundary reach.  Using very limited effort, we successfully captured 26 larvae with D-ring nets.  This was an important finding, because it is the first documented capture of sturgeon larvae in the Upper Columbia River.    The apparent high survival of hatchery fish planted as yearlings and the known production of larvae, indicates that the recruitment failure is occurring between these ages.  Possible causes of larval mortality include lack of suitable habitat, predation, and food limitation.  In order to assess these potential limiting factors, we need to develop an understanding of larval behavior.  We conducted D-ring sampling in 2005 and again captured sturgeon larvae; however, catch rates were low and effort was limited so there is still much to learn about larval behavior and habitat use.  By continued sampling of larvae with D-ring nets we can determine dispersal times, rates, and distances, potential post-dispersal rearing areas, and overlap with potential predators.  

We will conduct D-ring sampling for larval white sturgeon throughout the U.S. transboundary reach in June and July.  The sampling will be coordinated with egg mat sampling.  Larvae will be removed from nets, preserved, and staged in the laboratory to determine age and spawning date.

Juvenile Sampling:  Juvenile sampling is necessary to confirm the apparent limited recruitment in the upper Columbia River white sturgeon population, to identify recruitment years and year class sizes if they occur, and to monitor the dispersal, distribution, relative abundance, survival, and growth of hatchery juveniles released in Canada and the U.S.  We will use gill nets to representatively sample juvenile white sturgeon between Gifford and the Canadian border.  Sampling will be conducted during October in coordination with the Canadian juvenile monitoring.  We will sample in October to allow young-of-the-year fish to reach sizes that will recruit to the gill nets.

All sturgeon will be examined for existing marks and otherwise marked prior to release with individually numbered PIT tags and specific scute removal patterns.  Sturgeon will be measured (fork length, head length, and girth) and weighed.  Pectoral fin ray sections will be removed from wild fish and subsequently aged.  An external health assessment will be conducted.  Stomach samples will be collected from a sub-sample of juvenile hatchery sturgeon to identify key food items and trophic relationships.  These fish will come from juvenile hatchery fish released specific for this purpose in excess of recovery needs from specific release cohorts.

Telemetry Monitoring:  Since April 2003, Canadian and U.S. researchers have implanted sonic tags in approximately 100 sub-adult and adult and 100 hatchery juvenile white sturgeon in Lake Roosevelt and the upper Columbia River in Canada for monitoring of movements.  The fish were tagged during setline sampling for other purposes.  Movements are being monitored using strategically placed fixed station receivers between Gifford and Hugh Keenleyside Dam in British Columbia.  The sonic telemetry data should indicate the movement and mixing patterns of sturgeon between Lake Roosevelt and the Canadian reach.  Telemetry information is also providing information about potential spawning locations, seasonal movements, habitat use, and distribution.

We will deploy fixed station receivers at downstream locations in Lake Roosevelt to determine white sturgeon use in these areas, where data is currently lacking.  We will also actively track females.  

Sonic tags will be surgically implanted in as many as 10 maturing females expected to spawn during the following year.  Fish will be collected in conjunction with the adult/broodstock sampling.  Maturing females likely to spawn in the following spring will be identified by biopsy of developing oocytes.   Fish will be monitored at biweekly or weekly intervals from April through July and more frequently if apparent spawning movements are observed.  Spawning movements and locations will be tracked using a combination of mobile tracking and fixed station receivers.  GPS coordinates will be recorded.

Broodstock Collection:  In response to increasing concerns over the threat of extinction of Upper Columbia River white sturgeon, the UCWSRP identified that immediate implementation of a conservation aquaculture program was required to preserve the remaining demographic and genetic diversity of the transboundary reach population and rebuild the natural age-class structure lost during the persistent recruitment failures of the last 25-30 years (Measure 3.1).

An aquaculture program was established in Canada in 2001, with the first juveniles released in the Canadian transboundary reach in 2002.  Subsequent releases occurred in 2003 and 2004.  However, the UCWSRP suggested that existing hatchery facilities in Canada may be too small to fully address sturgeon recovery throughout the transboundary reach since Canadian release numbers are small and downstream dispersal into U.S. waters may be limited.  The UCWSRP asserts that the development of a U.S. hatchery program may be required to supplement Canadian efforts if production increases are warranted.  In addition to increased production, the UCWSRP identified that a U.S. sturgeon aquaculture facility would also provide a population failsafe.

An interim U.S. white sturgeon culture program was established in 2003-2005.  In February, 2004 we received 2,000 juvenile white sturgeon from one family group  (broodyear 2003) from the Canadian facility.  They were reared and marked at the Washington Department of Fish and Wildlife's (WDFW) Columbia Basin Hatchery, and subsequently released in the U.S. portion of the transboundary reach in May 2004.  In June 2004 and 2005, we received larvae and eggs from the Canadian hatchery for incubation and rearing at Columbia Basin Hatchery.  The fish were marked and released into the transboundary reach in Canada and the U.S.

In 2006, we plan to expand the U.S. aquaculture program to include broodstock collection and spawning of two families.  The reasons for expanding the aquaculture program are to ensure that the genetics diversity is being maximized in the aquaculture program.  The Canadian facility only has the capacity to rear six families, and the UCWSRP Breeding Plan indicates that there should be 12 families in planted in the transboundary reach and Lake Roosevelt.  Also, it is still unclear as to the amount of inter-breeding between the hypothesized sub-populations in the Canadian transboundary reach and Lake Roosevelt.  In order to insure that the genetic character of the fish in Lake Roosevelt is represented, they must be included as broodstock.  There are also questions related to the stress related impacts to transporting broodstock long distances from the Columbia River to the Canadian facility.  It has been hypothesized that fish transported short distances to local holding sites with river water as the water supply, will have higher rates for successfully spawning fish.

LITERATURE CITED:

Apperson, K. and P.J. Anders. 1991. Kootenai River white sturgeon investigations. Idaho Department of Fish and Game. Prepared for Bonneville Power Administration. Annual Progress Report, Project 88-65, Portland.

Auer, N.A. 1996. Response of spawning lake sturgeon to changes in hydroelectric facility operation.  Transactions of the American Fisheries Society 125:66-67.

Brannon, E., and seven others. 1987. Columbia River white sturgeon (Acipenser transmontanus)  population genetics and early life history study. Final Report. Project 83-316. Bonneville Power Administration, Portland.

Nilo, P., Durmont, P., and Furtin, R. 1997. Climatic and hydrological determinants of year-class strength of St. Lawerence River lake sturgeon (Acipenser fulvescens). Canadian Journal of Aquatic Science 54:774-780.

Paragamian V., G. Kruse, and V.D. Wakkinen. 1997. Kootenai River white sturgeon investigations. Annual Progress Report. Project 88-65. Bonneville Power Administration, Portland.

Parsley, M. 1991. How water velocities may limit white sturgeon spawning. Research Information Bulletin, U.S. Department of the Interior, U.S. Fish and Wildlife Service, 91-86.

Partidge, R. 1983. Kootenai River fisheries investigations. Idaho Department of Fish and Game. Job Completion Report, Project F-73-R-5, Boise.

R.L. & L. Environmental Services Ltd. 1994. Status of white sturgeon in the Columbia River, B.C. Final Report prepared for B.C. Hydro, Environmental Affairs, Vancouver, B.C. Report 377F.

Setter, A. And E. Brannon. 1992. A summary of stock identification research on white sturgeon of the Columbia River. Bonneville Power Administration, Project 89-44, Portland.