BC Conservation Data Centre: Conservation Status Report
Salvelinus confluentus
Bull Trout
| Scientific Name: | Salvelinus confluentus |
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| English Name: | Bull Trout |
| Provincial Status Summary | |
| Status: | S3S4 |
| Date Status Assigned: | January 02, 2012 |
| Date Last Reviewed: | April 26, 2018 |
| Reasons: | Widespread, however there is sensitivity to access development and habitat degradation, small individual populations sizes and long term population declines that appear to have stabalized. |
| Range | |
| Range Extent: | G = 200,000-2,500,000 square km |
| Range Extent Comments: | Occurs widely throughout BC, with the exception of Vancouver Island, Queen Charlotte Islands/Haida Gwaii and other coastal areas, and the western tributaries of the Columbia (including the Similkameen, Okanagan and Kettle systems) (McPhail and Carveth 1993). |
| Area of Occupancy (km2): | U = Unknown |
| Linear Distance of Occupancy: | U = Unknown |
| Area of Occupancy Comments: | The area of occupancy for bull trout populations is unknown. |
| Occurrences & Population | |
| Number of Occurrences: | E = > 300 |
| Comments: |
A recent draft analysis of bull trout data notes that ~1000 tributary watersheds in BC contain bull trout (John Hagen, unpublished data 2011). This will include all tributaries--there may be fewer EOs based on the EO specifications. Interior bull trout are present in 88 different water bodies in Region 3 Thompson Nicola, in 341 different water bodies in Region 4 Kootenay, in 251 different water bodies in Region 7 Peace, and in 15 different water bodies in Region 8 Okanagan (data from FISS 2011). Coastal bull trout are found in 47 different water bodies in Region 2 Lower Mainland (FISS 2011). |
| Number of Occurrences with Good Viability / Ecological Integrity: | U = Unknown |
| Number of Occurrences Appropriately Protected & Managed: | Rank Factor not assessed |
| Comments: | The number of protected occurrences is unknown. Bull trout habitat is protected by the federal Fisheries Act. |
| Population Size: | FG = 10,000 - 1,000,000 individuals |
| Comments: | The total population of bull trout is unknown. Based on expert opinion, 5,000-10,000 is likely the population of the coastal bull trout (Hagen and Decker 2011). Given the number of waterbodies included in the province, the number of mature fish undoubtedly ranges from tens to 100s of thousands. |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | B = High |
| Comments: | Susceptible to over-harvest. Hybridization with introduced/stocked brook trout, competition from introduced trout and char species. Creation of migration barriers e.g. hydroelectric development, road building. Habitat degradation (including increased stream temperature or decreased water quality, changes in stream hydrology, sedimentation, and impacts to groundwater supply) due to forest harvesting practices, oil and gas exploration, grazing, mining, and road development. |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | G = Relatively Stable (<=10% change) |
| Comments: |
A recent province-wide analysis of Bull Trout trend data, based on very few locations, noted an increase in most cases, where a previously depressed population was responding positively to more restrictive angling regulations (John Hagen, unpublished data 2011). Negative trends are observed in the Williston Reservoir (John Hagen, unpublished data 2011). There also were negative trends on the Squamish River where a toxic CN spill resulted in a significant decline (Hagen and Decker 2011) which is expected to level out soon and start rebuilding (Greg Wilson, Surrey MFLNRO, pers. comm. 2011). Pollard and Down (2001; reported in Hammond 2004) reported most bull trout populations to be stable with a few declining. Expert opinion for this group suggests that populations vary from declining to increasing -overall stable. |
| Long-Term Trend: | F = Decline of 10-30% |
| Comments: |
Due to extensive habitat impacts in the lower mainland and forestry impacts along the coast, it is likely that coastal bull trout populations have declined over the long-term. Declines probably in the range of 10-30%. Due to numerous dams along the Columbia River and the creation of the Peace Williston Reservoir, as well as the effects of forestry, mining and oil and gas development, it is likely that the interior population of bull trout has declined over the long-term. Overall, long-term trend is probably declining but now stable. |
| Other Factors | |
| Intrinsic Vulnerability: | B=Moderately vulnerable |
| Comments: | Bull trout mature late in life. However, they do exhibit diversity in this maturation and growth rate according to the habita that they are in (McClaren 1993). |
| Environmental Specificity: | C=Moderate. Generalist or community with some key requirements scarce. |
| Comments: | They are sensitive to disturbance and require relatively pristine habitats. However, they do exhibit diversity in habitat use and migration movements (McClaren 1993). |
| Other Rank Considerations: | Currently listed as threatened under US Endangered Species Act. Populations across species range in decline. Mitochondrial DNA research indicates the presence of 2 major evolutionary lineages - 'coastal' and 'interior' (Taylor et al. 1999). Most genetic variation occurs among populations and among geographic regions (Taylor et al. 1999); maintenance of genetic diversity requires conservation of as many populations as possible across species distribution and range; they do not appear to act as metapopulations (Taylor et al. 2001). Conservation of bull trout in B.C. critical to survival on a global level; B.C. harbours the majority of the remaining healthy bull trout populations. |
| Information Gaps | |
| Research Needs: | |
| Inventory Needs: | Monitoring population trends, genetic dynamics, basic life history. Research into current forest harvesting practices, agricultural practices, habitat-sensitive industrial development and mitigation techniques, conservation management techniques, regulation changes. Identification of specific risks. |
| Stewardship | |
| Protection: | Appropriate angling management and enforcement. Removal of reproductive populations of brook trout where feasible. Curtail movement of bull trout, other char or trout to waters already inhabited by native populations. |
| Management: | Information and education. Compliance with angling and habitat protection regulations. Acceptance of compatible agricultural practices and attention to access development issues. Rehabilitation and restoration of degraded habitat, blocked migration routes, and water flow, temperature and quality. |
| Version | |
| Author: | Woodruff, P. (edits by S. Pollard). |
| Date: | October 31, 2011 |
| References | |
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Haas, G.R. 1998. Indigenous fish species potentially at risk in BC with recommendations and prioritizations for conservation, forestry/resource use, inventory and research. Fish. Manage. Rep. No. 105, B.C. Minist. Fish., Res. and Dev. Sect., Vancouver, BC.
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McPhail, J.D., and R. Carveth. 1992. A foundation for conservation: the nature and origin of the freshwater fish fauna of British Columbia. Prepared for B.C. Minist. Environ., Lands and Parks, Victoria, BC. 39pp.
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State of Environment Reporting Program. 2000. Environmental Trends in British Columbia 2000. B.C. Minist. Environ., Lands and Parks, Victoria, BC. 56pp.
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Taylor, E.B., S. Pollard, and D. Louie. 1999. Mitochondrial DNA variation in bull trout (Salvelinus confluentus) from northwestern North America: implications for zoogeography and conservation. Mol. Ecol. 8:1155-1170.
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Taylor, E.B., Z. Redenback, A.B. Costello, S.M. Pollard, and C.J. Pacas. 2001. Nested analysis of genetic diversity in northwestern North American char, Dolly Varden (Salvelinus malma) and bull trout (Salvelinus confluentus). Can. J. Fish. Aquat. Sci. 58:406-420
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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. 2011. Conservation Status Report: Salvelinus confluentus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Dec 22, 2024).