Bull Trout | NWT Species at Risk

Bull trout - credit: DFO / Jeremy Stewart

Bull Trout (Western Arctic population)

Salvelinus confluentus

NWT List of Species at Risk:

Not applicable

NWT SARC Assessment:

Not applicable

Federal Species at Risk Act list:

Special Concern

COSEWIC Assessment:

Special Concern

NWT General Status Rank:

Sensitive

Description:

Bull Trout is a member of the trout and salmon family. It has a long and slender body, a large broad head with a prominent upper jaw, and a slightly forked tail fin. Its back is olive-green to blue-grey and its sides are silvery with small pink, lilac, yellow-orange or red spots. Its belly is pale-coloured and may become yellow, orange or red in males during spawning. Pelvic and anal fins have white leading edges with no black line.

Length varies based upon its life history (see habitat and biology): Resident, 250 to 410 mm. Fluvial, 400 to 730 mm. Adfluvial, 400 to 900 mm.

Report Bull Trout sightings to WILDLIFEOBS@gov.nt.ca

Distribution

Bull Trout is a coldwater species found in lakes, streams and rivers from sea level to mountainous areas. In Canada, Bull Trout is found in British Columbia, Alberta, Yukon and the Northwest Territories (NWT).

Bull Trout is widely distributed, but in low abundance, throughout much of central and southern NWT (Sahtu and Dehcho regions) in drainages west of the Mackenzie River. The northernmost known location is the Gayna River.

Range map information

Habitat and biology

There are four types of life history strategies used by Bull Trout. The resident form is isolated and spends its life in small rivers or streams. The fluvial form lives in small rivers and streams, migrating between spawning streams and larger streams. The adfluvial form is similar, but matures in lakes rather than streams and rivers. The anadromous form is found only in southwestern British Columbia and Washington, and migrates from spawning freshwater streams to the sea.

Bull Trout habitat is best described as cold, clean, complex and connected. Spawning occurs in the fall in water temperatures below 10°C in clean flowing streams over cobble or loose gravel. These areas are typically associated with groundwater sources. The female digs her nest (redd) accompanied by a dominant male who defends her eggs from other males. Some males termed “sneakers” are able to mimic females, allowing them to approach close enough to fertilize some of the eggs.

Bull Trout feeds on a wide variety of items including other fish. The typical maximum age of Bull Trout is unknown, but specimens have been recorded up to 24 years old.

Population size and trends

The Bull Trout (Western Arctic population) is broadly distributed but populations are never abundant. Little is known about population size and trend in the Northwest Territories. There is some evidence of decline in Alberta.

Threats

Potential threats to Bull Trout in the NWT include industrial activities and infrastructure projects that can lead to poor habitat quality and habitat fragmentation. Bull Trout are difficult to distinguish from other char and trout that are commercially fished, however there is minimal overlap in distribution with these species in the NWT.

Protection and recovery

COSEWIC assessed Bull Trout (Western Arctic population) as a species of Special Concern in 2012 because of small population size, evidence of decline in parts of the range, and biological factors that make it particularly vulnerable to threats. Bull Trout (Western Arctic population) was listed as Special Concern under the federal Species at Risk Act in 2019.

Area:

Dehcho, Sahtú, South Slave