BC Conservation Data Centre: Conservation Status Report
Acipenser transmontanus pop. 4
White Sturgeon (Lower Fraser River Population)
| Scientific Name: | Acipenser transmontanus pop. 4 |
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| English Name: | White Sturgeon (Lower Fraser River Population) |
| Provincial Status Summary | |
| Status: | S1S2 |
| Date Status Assigned: | April 24, 2018 |
| Date Last Reviewed: | April 24, 2018 |
| Reasons: | The vast majority of the fish occurs in a small area and number of locations in the lower Fraser River Valley, an area undergoing rapid growth and development. Habitat degradation is continuing, and fish are subject to mortality as by-catch in the commercial salmon fisheries, as well as being targeted in the catch and release fishery (COSEWIC 2012). |
| Range | |
| Range Extent: | DE = 1,000-20,000 square km |
| Range Extent Estimate (km2): | 3798 |
| Range Extent Comments: | This population occurs from the Fraser estuary upstream to a potential barrier (Hells Gate) located about 200 km upstream from the sea. The range extent when including the mainstem Fraser River only (most common habitat, probably where all spawning occurs): 3,798 km2. If Pitt and Harrison lakes are included: 6,177 km2 (COSEWIC 2012). |
| Area of Occupancy (km2): | G = 501-2,500 |
| Linear Distance of Occupancy: | EF = 101-2,000 |
| Area of Occupancy Comments: | Including only mainstem Fraser River: 804 km2; including Pitt and Harrison lakes as well: 1, 492 km2 (COSEWIC 2012). |
| Occurrences & Population | |
| Number of Occurrences: | AB = 1 - 20 |
| Comments: | There are 4 confirmed spawning sites and 2-3 likely but unconfirmed sites. There also are at least 2 major and several minor over-wintering sites (COSEWIC 2012). |
| Number of Occurrences with Good Viability / Ecological Integrity: | BC = 1 - 12 |
| Comments: | The abundance of white sturgeon in the area below Hell's Gate is relatively large and may be increasing as it recovers from over-harvest. However, abundance in this area is most likely well below its most productive level (Walters et al. 2005). There has been an increase in the number of adults, with a projected incrase of 5-10% over the next 3 generations; however, there has been a decline in the number of juveniles. An increase in reporductive adults indicates that at least some of the locations should be of good integrity (COSEWIC 2012). |
| Number of Occurrences Appropriately Protected & Managed: | A = None |
| Comments: | No harvest has been permitted since 1994. This species is currently listed under the Canadian Species at Risk Act in Schedule 3 as Special Concern. |
| Population Size: | EF = 2,500 - 100,000 individuals |
| Comments: |
Recent mark-recapture estimates indicate approximately 8,460 reproductive individuals; alternative estimates could be as high as 15,000 (COSEWIC 2012). There is an estimate of 44,713 total fish for 2011. 2004 population estimated at approximately 60,000 fish between 40 cm and 220 cm with evidence of an increasing population over the 2000-2004 study period. Number of individuals of reproductive age (140 cm or larger) is estimated at about 9,000 (Maximum Likelihood Estimate) based on continued mark-recapture studies (Nelson et al. 2004). Walters et al. (2005) indicates that the minimum estimate of abundance of 60 cm+ sturgeon is between 40,000 and 60,0000 individuals. |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | AB = Very high - high |
| Comments: |
Major threats include: loss or degradation of habitat from the elimination of sloughs, side channels and wetlands, dyking, channelization, dredging, gravel mining and contamination. Poaching and by-catch from other fisheries are also a threat (COSEWIC 2012). The emerging commercial aquaculture industry could have impacts, if it is not managed appropriately (concerns include facility placement and containment, security, access to wild broodstock or the importation of non-native stocks, and the possibility of masking and enhancing the market for illegally caught wild fish or their products (COSEWIC 2003). There is no direct evidence from the mark-recapture study of cumulative mortality due to repeated catch and release associated with the recreational fishery (Walters et al. 2005). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | E = Decline of 30-50% |
| Comments: |
COSEWIC (2012) estimates a decline of approximately 45% over the last three generations (35 years/generation), using Whitlock's (2007) analysis; Walters et al. (2006) estimates a decline up to 55%. From 2004-2011, there was an increase in the number of adults (from 4550 to 8460; COSEWIC 2012). Nelson et al. (2012) reported a 77% increase in the numbers of adult sturgeon from ~4,550 to 8,090 between 2004 and 2011 although wide confidence intervals on yearly estimates were present and the overall trend was not significant (r = 0.12, P = 0.73) (in COSEWIC 2012). The impact of the historical fishery varies depending on the interpretation of data available for the commercial sturgeon fishery (only total weight of landings was recorded). Under some scenarios using stock reduction analysis, Walters et al. (2005) were able to show that the numbers of fish removed may have been higher between 1960-80 due to interception in the commercial chinook gill net fishery; this is based on the assumption that the average size of the fish harvested in the early fishery was much greater than it was for those intercepted in the later salmon fishery. Catch data suggest the abundance of small fish (1-7 years) has been rapidly increasing since 2000; age and size composition data suggest relatively healthy numbers of older fish in the population that is either stable or increasing (Walters et al. 2005). |
| Long-Term Trend: | BD = Decline of 50-90% |
| Comments: | White sturgeon in the lower part of the river provided an important commercial fishery in the late 1800s and early 1900's; the annual harvest peaked at 517 tonnes and collapsed to 20 tonnes in 1905 due to overharvest (Echols 1995). Walters et al. (2006) estimate that the Lower Fraser white sturgeon population has declined by at least 50% since the late 1800's; Walters et al. (2005) suggests that the current egg production is only 10% of what the unexploited population was producing. |
| Other Factors | |
| Intrinsic Vulnerability: | A=Highly vulnerable |
| Comments: | Late age of maturation, slow growth, and long life span make this species extremely vulnerable. |
| Environmental Specificity: | A=Very narrow. Specialist or community with key requirements scarce. |
| Comments: | Adapted to free flowing, large, fast, turbid rivers. |
| Other Rank Considerations: | The scientific or appreciative value of this large, ancient species as part of our natural heritage can not be quantified. It is representative of an ancient lineage that is largely extinct; almost all of the remaining species are at risk (COSEWIC 2003). |
| Information Gaps | |
| Research Needs: | Additional information on life-history traits (including anadromy), habitat use and catch-and-release mortality studies are required to determine appropriate management strategies. The importance of the declines in forage species populations to recruitment should be determined. Information is required on the influence of abiotic and biotic factors on spawning and subsequent recruitment success. |
| Inventory Needs: | Regular population monitoring is needed to inform management practices. |
| Stewardship | |
| Protection: | Maintenance of spawning substrates and access to spawning and juvenile rearing habitat, and protection of water quality and quantity are required. |
| Management: | |
| Version | |
| Author: | Woodruff, P, L. Ramsay and J. Ptolomy |
| Date: | April 04, 2018 |
| References | |
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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.
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Echols, J.C. 1995. Review of Fraser River white sturgeon. Fraser River Action Plan, Fishery Manage. group, and Can. Dep. Fish. and Oceans. 33pp.
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Nelson, T.C. et al. 2004. Status of white sturgeon in the lower Fraser River. Report on the findings of the lower Fraser River white sturgeon monitoring and assessment program 1999-2004. Prepared for the Fraser River Stugeon Conservation Society, Vancouver, B.C., by LGL Limited environmental research associates. 97 pp.
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R.L. & L. Environmental Services Ltd. 2000. White Sturgeon Investigations in Arrow Reservoir and Columbia River, B.C. 1999 Study Results. Rep. prepared for Minist. Environ., Lands and Parks, Nelson, BC. R.L. & L. Report No. 754F: 38pp.+ 4app.
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Smith, C.T., et al. 2002. Population genetic analysis of white sturgeon (Acipenser transmontanus) in the Fraser River. J. Appl. Ichthyol. 18:307-312.
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Walters, C., J. Korman, and S. McAdam. 2005. An assessment of white sturgeon stock status and trends in the lower Fraser River. Prepared for BC Ministry of Water, Land and Air Protection and Fisheries and Oceans Canada. 67 pp.
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Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2018. Conservation Status Report: Acipenser transmontanus pop. 4. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jan 24, 2025).