Bull trout

Appearance

Like other species of char, the fins of a bull trout has white leading edges. Its head and mouth are unusually large for salmonids, giving it its name. Bull trout have been recorded measuring up to 103 cm in length and weighing 14.5 kg . Bull trout may be either migratory, moving throughout large river systems, lakes, and the ocean, or they may be resident, remaining in the same stream their entire lives. Migratory bull trout are typically much larger than resident bull trout, which rarely exceed 2 kg . Bull trout can be differentiated from brook trout by the absence of distinct spots on the dorsal fin, as well as yellow, orange, or salmon-colored spots on the back as opposed to red spots with blue haloes on the brook trout. Bull trout lack the deeply forked tail fin of lake trout .

Distribution

''S. confluentus'' is found in the cold, clear waters of the high mountains and coastal rivers of northwestern North America, including Yukon, British Columbia, Washington, Oregon, Idaho, and western Montana, as well as the Jarbidge River of northern Nevada. A population of bull trout exists east of the Continental Divide in Alberta, where it is the provincial fish. The historical range of bull trout also included northern California, but they are likely extirpated.

Bull trout have exacting habitat demands, requiring water temperatures generally below 55 °F , clean gravel beds, deep pools, complex cover such as snags and cut banks, and large systems of interconnected waterways to accommodate spawning migrations. Thus, they favor the deep pools of cold lakes and large rivers, as well as high, cold mountain headwaters. Bull trout may be anadromous in coastal rivers, and individual bull trout have been found to have migrated from one coastal river to another via the ocean.

Status

The bull trout is listed as a threatened species under the U.S. Endangered Species Act throughout its range in the contiguous United States. It is used as a management indicator species for several national forests, including Boise National Forest and Sawtooth National Forest . Bull trout can also be found in the Glacier National Park. Bull trout reproduction requires cold water and very low amounts of silt, both of which are negatively impacted by road building and logging. Additionally, the bull trout's need to migrate throughout river systems may be hindered by impassible fish barriers, such as dams.

Bull trout populations are also in danger from hybridization with non-native brook trout.

They are a prized game fish in northern Canada. Indeed, the fish was once maligned out of fear they threatened populations of other native species more prized by anglers. Some jurisdictions publicize the requirement to release with the slogan "No black, put it back."

Habitat

''S. confluentus'' is found in the cold, clear waters of the high mountains and coastal rivers of northwestern North America, including Yukon, British Columbia, Washington, Oregon, Idaho, and western Montana, as well as the Jarbidge River of northern Nevada. A population of bull trout exists east of the Continental Divide in Alberta, where it is the provincial fish. The historical range of bull trout also included northern California, but they are likely extirpated.

Bull trout have exacting habitat demands, requiring water temperatures generally below 55 °F , clean gravel beds, deep pools, complex cover such as snags and cut banks, and large systems of interconnected waterways to accommodate spawning migrations. Thus, they favor the deep pools of cold lakes and large rivers, as well as high, cold mountain headwaters. Bull trout may be anadromous in coastal rivers, and individual bull trout have been found to have migrated from one coastal river to another via the ocean.

Food

Young bull trout feed on zooplankton and zoobenthos, especially chironomids. As they grow larger, they begin to feed heavily upon other fish. In coastal Washington state, some of the southernmost populations of bull trout feed heavily on salmon eggs and fry, as well as fish.

Uses

The "Dolly Varden" name is also applied to the other subspecies of ''S. malma'', the ''S. m. krascheninnikova'', and ''S. m. miyabei'', found on the island of Hokkaidō in Japan.

The name has also been applied to ''S. alpinus'', today more commonly known as Arctic char.