White Sturgeon Middle Fraser River Stock Group

White Sturgeon Middle Fraser River Stock Group Acipenser transmontanus Prepared by Chris Gill, MSc, RPBio Forsite Phone: (250) 832-3366 Email: cgill@forsite.ca Disclaimer: The following document was compiled based on a review of information currently available for this species as of November 25, 2005. This document can be used to assist with the identification of this species and to support the development of management recommendations as they relate to forestry activities. For more information on this species, please refer to the reference section or consult with a Species at Risk specialist. Description The white sturgeon is the largest freshwater fish in Canada reaching up to 6 m in length, 635 kg in weight and over 100 years in age. The most distinguishing features of the white sturgeon include a mainly cartilaginous skeleton, long scaleless body covered with rows of large bony plates (called scutes) on the back and sides, shark-like (heterocercal) tail, and four barbels between the mouth and an elongated snout. The scutes are arranged in five rows one along the back, one along the middle of each side, and one along each side of the belly. The scutes of young sturgeon have very sharp points which become blunted with age 1,2. The white sturgeon has a broad, flattened head and small eyes. It has no teeth, but instead has a protrusible mouth with which it creates suction to pull in food. Body colouration ranges from black, to olive or light grey on the dorsal surface and upper edge of plates, but is consistently white on the ventral surface 1,2. Photo courtesy of the Fraser River Sturgeon Conservation Society

Photo courtesy of the Fraser River Sturgeon Conservation Society Distribution In British Columbia, the most widespread population occurs in the Fraser River mainstem inland to upstream of Prince George, high into the Nechako. The three Fraser River mainstem stocks include 3 : Lower Fraser River Fraser mainstem downstream of Hells Gate (0 to 211 km upstream) plus the Pitt River and Harrison River watersheds. Middle Fraser River Fraser mainstem from Hells Gate to the Cottonwood River confluence (211 to 670 km upstream). Upper Fraser River Fraser mainstem upstream of Prince George (790 to 1,100 km upstream). White sturgeon also occur in the British Columbia portion of the Columbia River drainage and the lower reaches of large tributaries like the Stuart, McGregor, Bowron, Harrison and Pitt rivers. There have also been reports of the white sturgeon in several lakes in the Columbia River drainage including Fraser, Takla, Trembleur, Stuart and Williams Lakes in the Fraser system, and Kootenay, Arrow, Slocan and Duncan Lakes in the Columbia watershed 2. 2

Distribution of white sturgeon (Acipenser transmontanus) in British Columbia 3. Proposed Population Breakdown 3 SP1: Lower Fraser River - downstream of Hell s Gate (km 0 to km 211) SP2: Middle Fraser River - Hell s Gate to Prince George (km 211 to km 790) SP3: Upper Fraser River - upstream of Prince George (km 790 to ~ km1,100) SP4: Nechako River (tributary of Fraser River, enters mainstem at Prince George) SP5: Upper Columbia River SP6: Kootenay River. Four populations of white sturgeon have been proposed for the Fraser River system (SP1-4) based on biology and DNA analysis studies. The lower Fraser River population (SP1) is likely the only facultative anadromous group in Canadian waters; the others are inland groups 3. 3

Forest Districts 4 Central Cariboo Forest District (DCC) Chilliwack Forest District (DCK) Cascades Forest District (DCS) Kamloops Forest District (DKA) 100 Mile House Forest District (DMH) Prince George Forest District (DPG) Quesnel Forest District (DQU) Biogeoclimatic Units 4 BGxw - Bunchgrass - Very Dry Warm CDF - Coastal Douglas Fir CWH - Coastal Western Hemlock IDF - Interior Douglas-fir PP - Ponderosa Pine SBS - Sub-Boreal Spruce Elevation Not available. 4

Map of Known Locations Known locations for white sturgeon (Acipenser transmontanus pop. 4), in the Cascades Forest District as of September 2005 (data source: Conservation Data Centre). 5

Known locations for white sturgeon (Acipenser transmontanus pop. 4), in the 100 Mile House Forest District as of September 2005 (data source: Conservation Data Centre). Note: Occurrence data could not be obtained for the Kamloops Forest District. Sightings in the North Thompson River were most likely isolated events. 6

Biology Reproduction White sturgeon are a slow-growing, long-lived species with a delayed onset of sexual maturity. Males tend to mature at a younger age and smaller size than females, but it is thought that age at first maturity increases with distance upstream. For example, age at first maturity in the middle Fraser stock is estimated to be in the late 20s for females while males may be younger. The upper Fraser stock is probably significantly older at first maturity than the lower Fraser stock given the slower growth rates and reduced productivity of this section of river 3,5. White sturgeon are non-annual spawners and may spawn multiple times throughout their life. Limited data for the lower Fraser stock suggests that intervals between spawning for females may vary from 4 to 11 years, with the interval increasing with age. It has been hypothesized that spawning frequency may be lower in the mid and upper Fraser, but this has not been assessed directly 3,6. Sturgeon make up for this pattern of delayed maturity and infrequent spawning by producing an exceptional numbers of eggs from about 700,000 in medium sized females to 3 or 4 million in the largest 2. Sexually mature adults gather in aggregations to broadcast spawn during spring and early summer. The fertilized small brown, sticky eggs fall to the bottom and adhere to the substrate. The length of time before the eggs hatch is temperature dependent and can last for 5 to 25 days. Yolk-sac larvae go through a dispersal period where they move vertically and swim or drift with the current. At 15 C the yolk sac is absorbed around 12 to 14 days of age and the larvae begin to actively feed during daylight 2,7. This initial time of first feeding for fish larvae is considered to be a critical period because it influences their subsequent survival and growth. Approximately 20 to 30 days after hatching, larvae transform into fry (young-of-the-year). At around 55 days, they orient to the current and swim freely 3. Foraging White sturgeon eat a variety of organisms from benthic (bottom-dwelling) invertebrates including crayfish, shrimp and clams to fish such as lamprey, salmon, eulachon and smelt. Smaller sturgeon tend to eat smaller invertebrates, while larger sturgeon consume mainly fish. White sturgeon will readily take live prey as well as carrion 8. Habitat Habitat use varies with life-history stage and season, and may involve migrations to spawning and feeding areas, making critical habitat difficult to define 3. Spawning White sturgeon spawning habitat is difficult to study as it is used during the time of the year when flood events occur and because the habitat exists only in large rivers. Spawning events have been documented between late June and early August for the lower Fraser stock. Spawning period duration may be shorter in the more-northern, colder regions, such as the upper Fraser River 2. In the lower Fraser River, there is evidence that spawning occurs only in side channels with substrates comprised of gravel, cobble and sand. Boulder and cobble predominated 7

one study site, which was located in a confined area of the main channel. Flows at apparent spawning sites are mainly non-turbulent with near-bed velocities averaging 1.7 m/s. The lower Fraser River generally has high levels of suspended sediment 2,9. In regulated systems sturgeon utilize fast, turbulent water over clean, large rocky substrate 10. Movements and Dispersal In the mid Fraser, information on movements of white sturgeon is quite limited. Research has indicated that the stock exhibited mainly localized feeding migrations of less than 10 km in the spring, although some moved more extensively downstream (> 20 km) and then moved back upstream in the fall. Movements to overwintering areas were varied, ranging from less than 10 km up to 37 km, likely reflecting proximity to overwintering habitat. Mature fish from the middle Fraser stock also demonstrated a significant range of spawning-related movements: they generally moved more than 10 km and up to 75 km 2,11. Juvenile habitat The lower reaches of tributaries, large backwaters, side channels and sloughs (a depression or hollow) are used by juvenile (>1m) sturgeons. Some important factors in determining high suitability rearing habitat are a water depth > 5 m, low velocities and variable current direction, high turbidity and relatively warm water. There is a distinct movement from sloughs and backwaters to mainstem areas as summer progresses 2,8. Data from the middle Fraser River (between Boston Bar and French Bar Canyon) indicate that larger juveniles occupy the same areas as those used by adult fish 2,11. Little data is available on juvenile habitat preferences in the Fraser watershed. Research on juvenile white sturgeon in the lower Columbia River (downstream of McNary Dam) indicated the following physical habitat features: 2 to 58 m depth, 0.1 to 1.2 m s-1 mean column velocity, and near-substrate velocity of 0.1 to 0.8 m s-1. In this study, young-ofthe-year were collected at sites with the following characteristics: 9 to 57 m depth, 0.2 to 0.6 m s-1 mean water column velocity, and 0.1-0.6 m s-1 near-substrate velocity. These observations suggest that juvenile white sturgeon may be found at a range of depths, but that they prefer slow to moderate water velocities 2,12. Adult habitat Most studies of adult habitat use have focused on the physical features of spawning habitat. Considerably less attention has been paid to other adult habitat requirements, such as overwintering, feeding and holding habitats, plus migration habitats. This seems to reflect a general belief that adult feeding and holding habitats are not limiting, whereas the availability of suitable habitats for spawning and early life stages are critical to population abundance 2. Although adults will briefly move into shallower areas to feed during spring and summer, in the Fraser River, they are typically found in deep near-shore areas, adjacent to heavy flows, defined by deposits of sand and fine gravels with backwater and eddy flow characteristics 2,11. Adults in less productive northern areas may be widely dispersed (including use of tributaries), and require longer migrations than in southern regions 2. For more information on adult habitat, please refer to the Fraser River White Sturgeon Conservation Plan, 2005. This document can be found at the following website: http://www.frasersturgeon.com/programs.html. 8

Photo courtesy of Murray Ward Conservation and Management Status 4 Provincial Rank: S2 (Provincially Imperiled) BC List: Red (Endangered) COSEWIC Status: E (Nov 2003) (Endangered) SARA Schedule: 3 (Special Concern) Threats Fraser River white sturgeon are divided into four distinct stock groups and the threats and challenges facing the species vary among these different stocks 2. Over the past century, most white sturgeon habitat in British Columbia has declined in quality and quantity, but quantitative measures are not available. River regulation and diversion has likely had the most severe influence on sturgeon habitat 10, 13, 14. While dams have had a major effect, habitat loss and degradation from other human activities has occurred in all drainages. Potential threats to the white sturgeon from timber harvesting include: increased siltation, changes in hydrology (water flow and quality), water temperature changes, alteration of key life history habitats (e.g. spawning and rearing habitats) and a reduction of key prey abundance due to habitat changes 2,15. These threats come from timber harvesting directly affecting the Fraser River, but also, and perhaps more importantly, from any streams that run into the Fraser. 9

Management Recommendations Identify and protect locations where White Sturgeon are found: obtain occurrence data from the Conservation Data Centre (http://srmwww.gov.bc.ca/cdc/) and if necessary conduct surveys to confirm presence or absence of this species. Conduct silvicultural activities in a manner that prevents or minimizes sediment delivery to aquatic habitats where this species may occur. Increased silting of substrate reduces habitat quality for this species including the loss of deep nearshore pools used by adult sturgeon. Maintain riparian habitat features (i.e. crown closure) especially within the Fraser Watershed to minimize impacts to unnatural fluctuations in water levels, temperature and flow to maintain white sturgeon habitat. Reduced water flow affects the availability of physical habitat and increases water temperatures during the warm summer months. Follow the Riparian Management Guidelines for S1 streams. Do not use pesticides near aquatic habitats where this species may occur. Please refer to the Fraser River White Sturgeon Conservation Plan, 2005 for more information on this species. This document can be found at the following website: http://www.frasersturgeon.com/programs.html. 10

References 1 Scott, W.B. and E.J. Crossman. 1973. Freshwater fishes of Canada. Bulletin 184. Fisheries Research Board of Canada. 2 Todd Hatfield, T. 1995. Draft Fraser River white sturgeon conservation plan, 2005. (http://www.frasersturgeon.com/pdf/frwsconservationplan_draftforpublicreview_july 2005.pdf) 3 COSEWIC. 2003e. COSEWIC assessment and update status report on the white sturgeon Acipenser transmontanus in Canada. Comm. on the Status of Endangered Wildl. in Can. Ottawa. vii+51pp. 4 BC Conservation Data Center. Website: http://srmapps.gov.bc.ca/apps/eswp. 5 Ptolemy, J. and R. Vennesland. 2003. Update COSEWIC status report on white sturgeon Acipenser transmontanus. Prepared for Committee On the Status of Endangered Wildlife In Canada. 6 Semakula, S.N. and P.A. Larkin. 1968. Age, growth, food and yield of the white sturgeon (Acipenser transmontanus) of the Fraser River, British Columbia. Fisheries Research Board of Canada. 25:2589-2602. 7 Conte, F.S., I. Doroshov, P. Lutes, and E.M. Strange 1988. Hatchery manual for the white sturgeon Acipenser transmontanus Richardson with application to other North American Acipenseridae. Publication 3322 Cooperative Extension University of California Division of Agriculture and Natural Resources. 104 p. 8 Lane, E.D. and M.L. Rosenau. 1995. The conservation of sturgeon stocks in the lower Fraser River watershed. A baseline investigation of habitat, distribution, age and population of juvenile white sturgeon (Acipenser transmontanus) in the lower Fraser River, downstream of Hope, B.C. Habitat Conservation Fund Project Final Report. 153p. 9 Perrin, C.J., L.L. Rempel, and M.L. Rosenau. 2003. White sturgeon spawning habitat in an unregulated river: Fraser River, Canada. Transactions of the American Fisheries Society 132: 154-165. 10 UCRRP. 2002. Draft upper Columbia River white sturgeon recovery and management plan. Recovery Plan prepared by the Upper Columbia River Recovery Team, January, 2002. 88 p. 11 RL&L Environmental Services Ltd. 2000. Fraser River White Sturgeon Monitoring Program - Comprehensive Report (1995 to 1999). Final Report Prepared for BC Fisheries. RL&L Report No. 815F: 92 p + app. [note: there are multiple data reports for each year of this study] 12 Parsley, M.J., L.G. Beckman, and G.T. McCabe, Jr. 1993. Habitat use by spawning and rearing white sturgeon in the Columbia River downstream of McNary Dam. Trans. Am. Fish. Soc., 122: 217 227. 13 Korman, J., and C. Walters 2001. Nechako River white sturgeon recovery planning: summary of stock assessment and October 2-3, 2000 workshop. Report prepared for B.C. Fisheries, March 30. 14 Anders, P.J., D.L. Richards, and M.S. Powell. 2001. The first endangered white sturgeon population: repercussions in an altered large river-floodplain ecosystem. 15 Troy Nelson, Executive Director Fraser River Conservation Society. Personal Communication. Sept. 23, 2005. 11