Bull Trout Saskatchewan - Nelson Rivers populations
Scientific Name: Salvelinus confluentus
Other/Previous Names: Bull Trout (Saskatchewan - Nelson River populations)
Taxonomy Group: Fishes
Last COSEWIC Assessment: November 2012
Last COSEWIC Designation: Threatened
SARA Status: No schedule, No Status
Image of Bull Trout
The Bull Trout (Salvelinus confluentus) belongs to the salmon and trout family (Salmonidae) and is part of the char subgroup that also includes Dolly Varden (S. malma), Lake Trout (S. namaycush), Brook Trout (S. fontinalis) and Arctic Char (S. alpinus). Bull Trout has the following characteristics: A long and slender body; a large broad head and prominent upper jaw; tail fin is slightly forked; its back is olive-green to blue-grey; its sides are silvery with small pink, lilac, yellow-orange or red spots; its belly is pale in colour, and may become yellow, orange or red in males during spawning; the pelvic and anal fins have white leading edges with no black line; and size at maturity is dependent upon life history. Resident populations average length are 250 millimeters (maximum 410 millimeters); fluvial populations are greater than 400 millimeters (maximum 730 millimeters); and adfluvial populations are also greater than 400 mm (maximum 900 millimeters). Anadromous populations may be larger still.
Distribution and Population
Bull Trout are found in western North America from northern Nevada through Oregon, Idaho, Montana, and Washington. The Canadian distribution extends throughout British Columbia and western Alberta, with a northern limit into the southern Yukon and the central portion of the Northwest Territories. Based on genetic analysis, range disjunction and distribution, Bull Trout have been divided into five designated units (DUs): Southcoast BC populations (DU1); Western Arctic (DU2); Yukon (DU3); Saskatchewan-Nelson (DU4); and Pacific populations (DU5). The Saskatchewan-Nelson Rivers populations (DU4) are restricted to Alberta and are found primarily in the drainages of the North and South Saskatchewan rivers.
The Bull Trout is a coldwater species found in lakes, streams and rivers from sea level to mountainous areas. Its habitat has been described by the U.S. Fish and Wildlife Service as “cold, clean, complex and connected.”
There are four types of life history strategies used by Bull Trout, including: 1) resident; 2) fluvial; 3) adfluvial; and 4) anadromous. A resident form spends its life in small rivers or streams, isolated by physical, chemical or other forms of barriers. The fluvial form completes its life cycle in small rivers and streams, migrating between natal streams and larger streams. The adfluvial form is similar, but matures in lakes rather than streams and rivers. The anadromous form, which is found only in southwestern British Columbia and northwestern Washington, migrates from natal freshwater streams to feeding habitat at sea. Sexual maturity occurs between five and seven years of age. Spawning occurs in the fall, when water temperatures fall below 10 degrees Celsius. Preferred spawning areas are cold, unpolluted moving streams with cobble or loose gravel substrates and are associated with groundwater sources. The female digs a “red” in the center of the channel, and is accompanied by a dominant male, who defends her from other males competing for fertilization. Some males, termed “sneakers” are able to mimic females, allowing them to approach close enough to fertilize some of the eggs.
The greatest threats to Bull Trout include degraded and fragmented habitat resulting from development and the introduction of non-native species. Bull Trout are vulnerable to hybridization with introduced Brook Trout in areas where both species now occur. Impacts from oil and gas development, forestry, mining, transportation infrastructure and hydroelectric projects affect habitat by increasing siltation and water temperatures or decreasing stream flow volumes. In turn, these changes reduce reproductive success. As well, barriers to fish movement, such as dams, weirs, and elevated stream temperatures, fragment migratory corridors required for spawning. Overfishing may also remain a threat. As Bull Trout are difficult to distinguish from other char and trout being recreationally fished, the misidentification by fishers also poses a risk.
In Canada, this species is afforded protection under the Fisheries Act, and is currently under consideration for listing as Threatened under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available online at AquaticSpeciesAtRisk.ca or on the SARA Registry at SaraRegistry.gc.ca.
Provincial and Territorial Protection
Other Protection or Status
At a provincial/territorial level, the Bull Trout is considered a Species of Special Concern by Alberta, and is considered as May be at Risk by the Northwest Territories.
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
5 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Action Plans (1 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
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