Species Profile

Bull Trout Western Arctic populations

Scientific Name: Salvelinus confluentus
Taxonomy Group: Fishes
Range: Yukon, Northwest Territories, British Columbia, Alberta
Last COSEWIC Assessment: November 2012
Last COSEWIC Designation: Special Concern
SARA Status: No schedule, No Status

Individuals of this species may be protected under Schedule 1 under another name; for more information see Schedule 1, the A-Z Species List, or if applicable, the Related Species table below.


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Quick Links: | Photo | Description | Habitat | Biology | Threats | Protection | Other Protection or Status | National Recovery Program | Documents

Image of Bull Trout

Bull Trout Photo 1

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Description

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 millimeters (maximum 900 millimeters). Anadromous populations may be larger still.

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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 Western Arctic populations (DU2) include those populations in the Mackenzie River system and major tributaries, such as the Liard, Peace and Athabasca rivers.

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Habitat

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.”

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Biology

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. Biological characteristics of the Bull Trout, such as body size and diet for example, can be highly variable depending on the various life history strategies employed. Bull Trout are opportunistic feeders, however juveniles tend to prefer aquatic insects and invertebrates, and adults generally prey on fish.

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Threats

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.

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Protection

Federal Protection

In Canada, this species is afforded protection under the Fisheries Act, and is currently under consideration for listing as Special Concern 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

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.

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Other Protection or Status

At a provincial/territorial level, the Bull Trout is considered a Species of Special Concern by Alberta (http://srd.alberta.ca/FishWildlife/WildSpecies/Fish/SalmonTroutRelated/BullTrout/BullTrout.aspx) , and is considered as May be at Risk by the Northwest Territories (http://nwtspeciesatrisk.ca/tiki/tiki-index.php?page=SpeciesAtRisk).

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Documents

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.

4 record(s) found.

COSEWIC Status Reports

  • COSEWIC Assessment and Status Report on the Bull Trout Salvelinus confluentus in Canada (2013)

    Bull Trout is a large char. This salmonid derives its name from its large head and jaws. Bull Trout are olive-green to blue-grey in colour and pale round spots on their flanks and back distinguish them from most other similar-looking salmonids. It is difficult to visually distinguish them from Dolly Varden char, however, and detailed measurements or genetic analyses are required for accurate identification where their ranges overlap. Because of its very specific habitat requirements, this sportfish is highly sensitive to habitat changes. Bull Trout are, therefore, viewed as an indicator species of general ecosystem health. Based on genetic analysis, range disjunction and distribution across National Freshwater Biogeographic Zones, five designatable units are recognized; Genetic Lineage 1 (Southcoast BC populations) and Genetic Lineage 2 (Western Arctic, Yukon, Saskatchewan-Nelson and Pacific populations).

Response Statements

  • Response Statement - Bull Trout, Western Arctic populations (2013)

    This freshwater fish is broadly distributed throughout the Western Arctic drainage although populations are never abundant. There are areas with evidence of decline in numbers and distribution but quantitative estimates for the whole range are lacking. This is a slow-growing and late maturing species that thrives in cold, pristine waters, and many populations require long unimpeded migratory routes joining spawning to adult habitat. Therefore the species is particularly vulnerable to habitat degradation, fragmentation of river networks by dams, negative effects from the invasion of the non-native Eastern Brook Trout, and overharvest, but these threats are localized within its range.

COSEWIC Annual Reports

  • COSEWIC Annual Report – 2012-2013 (2013)

    Under Canada’s Species at Risk Act (SARA), the foremost function of COSEWIC is to “assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species”. COSEWIC held two Wildlife Species Assessment Meetings in this reporting year (October, 2012 to September 2013) from November 25 to November 30, 2012 and from April 28 to May 3, 2013. During the current reporting period, COSEWIC assessed the status or reviewed the classification of 73 wildlife species. The wildlife species assessment results for the 2012-2013 reporting period include the following: Extinct: 0 Extirpated: 2 Endangered: 28 Threatened: 19 Special Concern: 19 Data Deficient: 4 Not at Risk: 1 Total: 73 Of the 73 wildlife species examined, COSEWIC reviewed the classification of 50 species that had been previously assessed. The review of classification for 26 of those species resulted in a confirmation of the same status as the previous assessment.

Consultation Documents