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The bull trout (''Salvelinus confluentus'') is a
char Char may refer to: People * Char Fontane, American actress * Char Margolis, American spiritualist * René Char (1907–1988), French poet *The Char family of Colombia: ** Fuad Char, Colombian senator ** Alejandro Char Chaljub, mayor of Barranquill ...
of the family Salmonidae native to northwestern
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
. Historically, ''S. confluentus'' has been known as the " Dolly Varden" (''S. malma''), but was reclassified as a separate species in 1980. Bull trout are listed as a
threatened species Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of '' critical depen ...
under the U.S.
Endangered Species Act The Endangered Species Act of 1973 (ESA or "The Act"; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of ec ...
(1998) and as vulnerable on the
IUCN Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...
.


Description

Like other species of char, the fins of a bull trout have white leading edges. Its head and mouth are unusually large for salmonids, giving it its name. Bull trout have been recorded measuring up to in length and weighing . 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 . Bull trout can be differentiated from
brook trout The brook trout (''Salvelinus fontinalis'') is a species of freshwater fish in the char genus ''Salvelinus'' of the salmon family Salmonidae. It is native to Eastern North America in the United States and Canada, but has been introduced elsewhere ...
(''S. fontinalis'') by the absence of distinct spots on the
dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...
, as well as yellow, orange, or salmon-colored spots on the back as opposed to red spots with blue halos on the brook trout. Bull trout lack the deeply forked tail fin of
lake trout The lake trout (''Salvelinus namaycush'') is a freshwater char living mainly in lakes in northern North America. Other names for it include mackinaw, namaycush, lake char (or charr), touladi, togue, and grey trout. In Lake Superior, it can also ...
(''S. namaycush'', another char).


Distribution and habitat

''S. confluentus'' is found in the cold, clear waters of the high mountains and coastal rivers of northwestern
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
, including
Yukon Yukon (; ; formerly called Yukon Territory and also referred to as the Yukon) is the smallest and westernmost of Canada's three territories. It also is the second-least populated province or territory in Canada, with a population of 43,964 as ...
,
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...
,
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...
,
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
,
Idaho Idaho ( ) is a U.S. state, state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Monta ...
, and western
Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...
, as well as the
Jarbidge River The Jarbidge River is a , high elevation river in Elko County, Nevada and Owyhee County, Idaho in the United States. The Jarbidge originates as two main forks in the Jarbidge Mountains of northeastern Nevada and then flows through basalt and rh ...
of northern
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
. A population of bull trout exists east of the
Continental Divide A continental divide is a drainage divide on a continent such that the drainage basin on one side of the divide feeds into one ocean or sea, and the basin on the other side either feeds into a different ocean or sea, or else is endorheic, not c ...
in
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest T ...
, where it is the provincial fish. The historical range of bull trout also included northern
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
, but they are likely extirpated.Washington's Native Chars
, Washington Department of Fish and Wildlife
Bull trout have exacting habitat demands, requiring water temperatures generally below 55 °F (13 °C), clean
gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...
beds, deep pools, complex cover such as snags and
cut bank A cut bank, also known as a river cliff or river-cut cliff, is the outside bank of a curve or meander in a water channel (stream), which is continually undergoing erosion.Essentials of Geology, 3rd Ed, Stephen Marshak Cut banks are found in abu ...
s, 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 Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousa ...
in coastal rivers, and individual bull trout have been found to have migrated from one coastal river to another by the ocean., King County, Washington


Feeding

Young bull trout feed on
zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
and zoobenthos, especially
chironomid The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many specie ...
s. As they grow larger, they begin to feed heavily upon other fish. In coastal Washington, some of the southernmost populations of bull trout feed heavily on
salmon Salmon () is the common name for several commercially important species of euryhaline ray-finned fish from the family Salmonidae, which are native to tributaries of the North Atlantic (genus '' Salmo'') and North Pacific (genus '' Onco ...
eggs and fry, as well as fish.


Conservation

The bull trout is listed as a threatened species under the U.S. Endangered Species Act throughout its range in the
contiguous United States The contiguous United States (officially the conterminous United States) consists of the 48 adjoining U.S. states and the Federal District of the United States of America. The term excludes the only two non-contiguous states, Alaska and Hawaii ...
. It is used as a management indicator species for several national forests, including Boise National Forest and
Sawtooth National Forest Sawtooth National Forest is a National Forest that covers 2,110,408 acres (854,052 ha) in the U.S. states of Idaho (~96 percent) and Utah (~4 percent). Managed by the U.S. Forest Service in the U.S. Department of Agriculture, it was originall ...
(
Sawtooth National Recreation Area The Sawtooth National Recreation Area (SNRA) is a national recreation area in central Idaho, United States that is managed as part of Sawtooth National Forest. The recreation area, established on August 22, 1972, is managed by the U.S. Forest Se ...
). They can also be found in the Glacier National Park. Bull trout reproduction requires cold water and very low amounts of
silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel ...
, both of which are negatively impacted by road building and logging. Additionally, its 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 Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...
with non-native brook trout. Several of these issues were raised in a long-running lawsuit where in 2003, the Oregon Natural Desert Association and the Center for Biological Diversity sued the U.S. Forest Service claiming they violated the
National Forest Management Act The National Forest Management Act (NFMA) of 1976 (P.L. 94-588) is a United States federal law that is the primary statute governing the administration of national forests and was an amendment to the Forest and Rangeland Renewable Resources Pla ...
and Wild and Scenic Rivers Act by approving grazing plans in Oregon's Malheur National Forest. In April, 2018, U.S. District Judge
Michael W. Mosman Michael Wise Mosman (born December 23, 1956) is a Senior United States district judge of the United States District Court for the District of Oregon. He served as Chief Judge for the U.S. District Court for the District of Oregon from February ...
dismissed the complaint. They are a prized
game fish Game fish, sport fish or quarry refer to popular fish pursued by recreational anglers, and can be freshwater or saltwater fish. Game fish can be eaten after being caught, or released after capture. Some game fish are also targeted commercial ...
in
northern Canada Northern Canada, colloquially the North or the Territories, is the vast northernmost region of Canada variously defined by geography and politics. Politically, the term refers to the three territories of Canada: Yukon, Northwest Territories an ...
. It 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".


Historical names


"Dolly Varden" in California

Historically, confusion has existed between ''S. confluentus'' and '' Salvelinus malma malma'', today commonly called the Dolly Varden trout. This was likely due to overlapping ranges and similar appearances among members of the two species. The first recorded use of the name "Dolly Varden" for a fish species was applied to members of ''S. confluentus'' caught in the
McCloud River The McCloud River is a longU.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed March 10, 2011 river that flows east of and parallel to the upper Sacramento River, in Siskiyou County and S ...
in northern California in the early 1870s. In his book ''Inland Fishes of California'', Peter Moyle recounted a letter from Mrs. Valerie Masson Gomez: In 1874, Livingston Stone, a naturalist working for the U.S. government, wrote of this fish: It is currently unknown whether the name "Dolly Varden" was later applied to ''S. m. malma'' because of its similar appearance to ''S. confluentus''; the two may have even been believed to be the same species. The name "Dolly Varden" may have also been given to ''S. m. malma'' independent of the McCloud River fish. Ironically, the original "Dolly Varden" trout (i.e., ''S. confluentus'') apparently likely became extirpated in the McCloud River in the 1970s, although reports continue of its being caught. Other fish species, typically introduced trout, outcompete ''S. confluentus'', and can interbreed with them, resulting in sterile hybrids. An attempt to reintroduce ''S. confluentus'' to the McCloud was unsuccessful, and no additional attempts are expected.


Other uses of "Dolly Varden"

The "Dolly Varden" name is also applied to the other subspecies of ''S. malma'', the ''S. m. krascheninnikova'', and ''S. m. miyabei'', found in
Lake Shikaribetsu A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...
on the island of
Hokkaidō is Japan, Japan's Japanese archipelago, second largest island and comprises the largest and northernmost Prefectures of Japan, prefecture, making up its own List of regions of Japan, region. The Tsugaru Strait separates Hokkaidō from Honshu; th ...
in
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
.Use of Dolly Varden name in Japan
/ref> The name has also been applied to ''S. alpinus'', today more commonly known as
Arctic char The Arctic char or Arctic charr (''Salvelinus alpinus'') is a cold-water fish in the family Salmonidae, native to alpine lakes and arctic and subarctic coastal waters. Its distribution is Circumpolar North. It spawns Spawn is the eggs a ...
.


"Bull trout" in Europe

The name "bull trout" was also given in the past to some of the large sea trout that run the
River Tweed The River Tweed, or Tweed Water ( gd, Abhainn Thuaidh, sco, Watter o Tweid, cy, Tuedd), is a river long that flows east across the Border region in Scotland and northern England. Tweed cloth derives its name from its association with the R ...
and other rivers in
Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...
and
North East England North East England is one of nine official regions of England at the first level of ITL for statistical purposes. The region has three current administrative levels below the region level in the region; combined authority, unitary author ...
. Victorian anglers and others classified these as a separate race, but today they are biologically classified along with all other UK brown and sea trout as '' Salmo trutta''. This does not deny that populations of ''S. trutta'' can differ appreciably in habits, size, and appearance from place to place, or indeed in the same river or lake.


References

{{Taxonbar, from=Q2429513 Salvelinus Fish of Japan Fish of North America Fish of the Western United States Provincial symbols of Alberta Fish described in 1859 ESA threatened species