Salvelinus confluentus

Occurs in deep pools of large cold rivers and lakes (Ref. 5723). Most common in high mountainous areas where snowfields and glaciers are present (Ref. 5723). Rarely anadromous (Ref. 5723, Ref. 51243). Lacustrine form matures in lakes and spawns in tributaries, where young reside for one to three years (Ref. 10367).

Salvelinus confluentus, also called the bull trout or inland dolly varden, is most closely associated with pristine mountainous areas of the northwestern United States and Canada where cold, clean waters flow. The geographic range of S. confluentus is confined to northwestern North America from Alaska to northern California (Bjornn, 1991). The species is generally considered to live within the Arctic, Pacific and Missouri River drainages in mountain and coastal streams (Page and Burr, 1991). More specifically, the southern limit of the species has historically been within the McCloud River drainage system of northern California. East of this limit, S. confluentus occurs in the Columbia River drainage in northern Nevada and north to the extreme southern Yukon Territory (Page and Burr, 1991). Some drainage systems in Montana, particularly the Flathead system located on the western slope of the continental divide, sustain S. confluentus as well. In the United States, Idaho, Nevada, Montana, Oregon and Washington all contain some native stocks of bull trout. In Canada, the provinces of British Columbia and Alberta have existent populations located on both sides of the Continental Divide (Nelson and Paetz, 1992).

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) North-south distribution in coastal and montane areas of Pacific Northwest between about 48 and 61 degrees N latitude, north to the Yukon and Liard river drainages in northern British Columbia and adjacent Yukon Territory (Haas and McPhail 1991); occurs in most drainages on both sides of Continental Divide (Lee et al. 1980). Coastal and mountain streams of Arctic, Pacific, and Missouri River drainages from extreme southern Yukon through western Canada Washington, Idaho, Montana, and Oregon to the headwaters of Columbia River drainage in northern Nevada (Jarbridge River distinct population segment) and (formerly) the McCloud River drainage below Lower Falls in California (extirpated in California); locally common, rare in southern part of range; in the United States, extirpated from most of the large rivers that historically were occupied (California DF&G 1990, Page and Burr 1991).

Klamath River population segment occurs in south-central Oregon (USFWS 1997). Columbia River population segment occurs in Idaho, Montana, Oregon, Washington, and British Columbia (USFWS 1997).

Historic Range:

U.S.A, coterminous (lower 48 states)

Coastal and mountain streams of Arctic, Pacific, and Missouri River drainages from extreme southern Yukon in Canada to headwaters of Columbia River drainage in northern Nevada, USA, and McCloud River drainage in northern California, USA.

North America.

The bull trout, although similar in appearance, is not a true trout (Oncorhynchus sp.). Several characteristics differentiate them and likewise all of the char. The primary attributes that distinguish S. confluentus are the lack of teeth on the roof of the mouth and the presence of light spots on a dark background versus dark spots on a lighter background which true trout possess (Bjornn, 1991; USFWS, 1998). The general non-spawning coloration of the species is an olive to blue-gray back with some gray to silver tones on the fish's sides (Nelson and Paetz, 1992). Spot coloration can be red, yellow or orange and can often times be a combination of the three (Nelson and Paetz, 1992). Another trait that is often present and distinguishes the bull trout from other genera is the presence of a white margin on the leading edge of the ventral fins (Bjornn, 1991).

The species, as do all salmonids, display sexual dimorphism. In preparation for spawning, the breeding male can possess magnificent coloration that is characterized by red to orange lower sides and a belly of similar coloration. The appearance of the female is similar to the male during the non-spawning season but is generally more gray to silver in coloration. During the spawning period the female retains these colors with little or no change.

Individuals living in streams do not often grow larger than 4 kg, but the lake inhabitants, which have a longer migration to spawing sites, can acheive more than 9 kg (USFWS, 1998).

Range mass: 4-9 (high) kg.

Other Physical Features: bilateral symmetry

Length: 90 cm

Maximum size: 910 mm TL

103 cm TL (male/unsexed; (Ref. 40637)); max. published weight: 14.5 kg (Ref. 4699)

S. confluentus is usually found in medium to large river systems but can also occur in large lakes and reservoirs when conditions are adequate. In the fluvial setting the bull trout favors deep pools where it usually sits on or near the bottom (Bjornn, 1991). In the lacustrine setting the species frequents the cold, deeper sections of lakes as well as the shallows. The particular location of Salvelinus confluentus within a lake is dependant on the time of year and water temperature. Within their habitat the species generally prefers temperatures below 50 degrees Fahrenheit (Bjornn, 1991).

Although most representatives of the species are of the inland form, some populations of bull trout are anadromous and can co-exist with dolly varden char along the coast. These bull trout begin life in tributaries draining to the ocean and spend only a short period of their juvenile life in the stream. After entering the marine environment they spend up to three years feeding and maturing. When sexual maturity is reached, they return to freshwater for the sole purpose of spawning.

Habitat Regions: freshwater

Terrestrial Biomes: forest ; mountains

Aquatic Biomes: lakes and ponds; rivers and streams; coastal

Systems

• Freshwater
• Marine

benthopelagic; freshwater; brackish

Habitat Type: Freshwater

Comments: Habitat includes the bottom of deep pools in cold rivers and large tributary streams, often in moderate to fast currents with temperatures of 45-50 F; also large coldwater lakes and reservoirs. In the contiguous U.S., now extirpated in most large rivers that historically were inhabited; confined mostly to headwater streams. Conditions that favor the persistence of populations include stable channel, relatively stable stream flow, low levels of fine substrate sediments, high stream channel complexity with various cover types, temperatures not exceeding about 15 C, and the presence of suitable corridors for movement between suitable winter and summer habitats and for genetic exchange among populations (Rieman and McIntyre 1993).

Migratory forms live in tributary streams for up to several years before migrating downstream into a larger river or lake, where they spend several years before returning to tributaries to spawn (Rieman and McIntyre 1993). Some or most juveniles move to larger rivers or to a lake by mid-summer, while others stay in spawning areas for 2-4 years (Spahr et al. 1991). Adults return to river or lake after spawning in small streams. May move to lower reaches of mainstream river for winter. Resident populations often occur in small headwater streams where they spend their entire lives (see Rieman and McIntyre 1993). In lakes, inhabits all depths in fall, winter, and spring; moves to cooler, deeper water for summer.

Spawning usually occurs in gravel riffles of small tributary streams, including lake inlet streams. Spawning sites often are associated with springs (Rieman and McIntyre 1993). According to California Department of Fish and Game (1990), spawning requires a large volume of cold water. Optimum temperatures for incubation are about 2-4 C (see Rieman and McIntyre 1993). Constructs spawning redd. Young are closely associated with stream channel substrates (Rieman and McIntyre 1993). Areas with large woody debris and rubble substrate are important as juvenile rearing habitat (Spahr et al. 1991).

Depth range based on 16 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 0.15 - 4.5

Graphical representation

Depth range (m): 0.15 - 4.5
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Two distinct forms, resident and migratory, exist throughout the range (Rieman and McIntyre 1993). Migratory form migrates between spawning and nonspawning habitats; migrates upstream to spawning areas in spring. Anadromy has not been documented but may have been important in the past (see Rieman and McIntyre 1993).

After departing from the spawning redd in spring the young bull trout begins looking for suitable habitat for protection and food sources. As a juvenile, the first year in the life of the bull trout is spent eating small aquatic invertebrates (Bjornn, 1991; USFWS, 1998). These aquatic larvae, often ephemeropterans or dipterans (Bjornn, 1991), are readily available in the lower water column and interstitial spaces that these juveniles inhabit. As the bull trout grows larger, their diet, in addition to aquatic invertebrates, consists of other fish species (Bjornn, 1991). This increased piscivorous behavior increases as the fish grows. Of all salmonids, namely the salmon and trout, S. confluentus is more inclined to feed on fish. In certain parts of their range the mountain whitefish (Prosopium williamsoni) comprise a large part of the bull trout diet (Bjornn, 1991). In addition to whitefish bull trout will feed on sculpins, darters or other trout and where applicable, salmon fry (USFWS, 1998).

Animal Foods: fish; insects

Primary Diet: carnivore (Piscivore , Insectivore )

Occurs in deep pools of large cold rivers and lakes (Ref. 5723). Most common in high mountainous areas where snowfields and glaciers are present (Ref. 5723). Rarely anadromous (Ref. 5723). Lacustrine form matures in lakes and spawns in tributaries, where young reside for one to three years (Ref. 10367).

Comments: Eats terrestrial and aquatic insects, macrozooplankton, mysids, and fishes. Young feed heavily on aquatic insects. Adults feed principally on fishes, but have also been known to eat other small vertebrates, including frogs, snakes, mice, ducklings, etc. (Moyle 1976).

In the natural and unaltered fluvial or lacustrine setting, S. confluentus does not have many predators. As would be assumed with juvenile or young fish, some predation could occur from piscivorous birds. The greatest threat to the species however is most likely other fish species, specifically introduced non- indigenous species. Other fishes, such as trout, that are introduced into a drainage can either prey on young bull trout or compete with them directly for food (Bjornn, 1991).

One particular scenario that has been documented occurred in Priest Lake, Idaho. In this instance both brook trout (S. fontinalis) and lake trout (S. namaycush) were introduced into the drainage. In tributaries feeding the lake, brook trout competed with young bull trout for food and in the lake, lake trout preyed on bull trout (Bjornn, 1991). This eventually took a toll on the bull trout population as this type of predation and competition prevents many from reaching maturity and subsequently reduces number of future spawning stock (Bjornn 1991).

Another threat to the preservation and viability of the bull trout is the incidence of capture by humans. Being easily caught by the angler makes the species quite vulnerable to overfishing (Bjornn, 1991).

Known Predators:

• birds (Aves)
• lake trout (Salvelinus namaycush)

Salvelinus confluentus is prey of:
Aves
Salvelinus namaycush

This list may not be complete but is based on published studies.

Salvelinus confluentus preys on:
Actinopterygii
Insecta

This list may not be complete but is based on published studies.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 - 300

Comments: This species is represented by a large number of occurrences (subpopulations).

Klamath River population segment comprises seven disconnected populations (USFWS 1997). Columbia River population segment comprises 386 populations (USFWS 1997).

100,000 to >1,000,000 individuals

Comments: Total adult population size is unknown but presumably exceeds 100,000.

Resident and migratory form live together but whether they represent a single population or separate populations is unknown (Rieman and McIntyre 1993).

Vigorous populations may require abundant fish forage (Rieman and McIntyre 1993).

Available information indicates that bull trout and other native fishes use different resources, reducing direct competition (Rieman and McIntyre 1993).

Communication Channels: visual ; acoustic

Perception Channels: tactile ; chemical

The life cycle of the bull trout can be separated into five periods of development (Moyle and Cech, 2000). As with most salmonids the rate of development for bull trout embryos is primarily temperature driven(Bjornn, 1991). After egg deposition in the fall, relatively warm temperatures facilitate rapid embryonic development (Bjornn, 1991). These warmer temperatures, usually 40-50 degrees F, are followed by much colder winter temperatures that approach freezing and subsequently decrease the rate of embryonic development (Bjornn, 1991). As winter progresses into spring and temperatures increase, the rate of development is again increased.

The first developmental period is the embryonic stage in which the fish's growth is reliant on the yolk sac. The embryonic stage can be further broken down. The first part of the embryonic period is the cleavage stage and is accepted to be the time between the first occurrence of cell division and the development of pre-organ systems (Moyle and Cech, 2000). This is followed by the embryo stage in which the organs are formed (Moyle and Cech, 2000). This stage ends with hatching, at which time the animal is no longer confined to the shape of the egg. Most bull trout throughout the range hatch from the egg between 100-120 days. The free-embryo stage follows and is the period in which the fish is still dependent on the protein of the egg sac but is more fish-like in nature (Moyle and Cech, 2000).

The larval period of S. confluentus is not unlike other salmonids in that at this time the fish leaves the spawning site and begins to feed on it's own. In mid spring, after the larval fish has absorbed its yolk sac, it emerges from the redd as an alevin and proceeds to find suitable habitat for the summer period. This usually occurs 200-230 days after spawning (Bjornn, 1991).

The juvenile period follows the larval period and is generally demarcated by the presence of fully formed organ systems and fins (Moyle and Cech, 2000). Other than coloration, the bull trout at this stage is essentially a miniscule version of the adult form (Moyle and Cech, 2000).

With the maturation of bull trout, gonads are fully capable of performing sexual reproduction and the fish is considered to be in the adult stage. Behavioral changes in the species and the development of spawning colors are characteristic of this stage (Moyle and Cech, 2000).

The senescent period which is the last and final stage in the life of bull trout as well as other salmonids occurs when the fish is sexually degenerative. With the onset of this period of "old age" the fish has essentially stopped growing (Moyle and Cech, 2000).

The lifespan and longevity of the bull trout is not well documented but seems to be approximately 10-12 years (USFWS, 1998). In the lacustrine setting, where the species attains much greater size, it would seem that bull trout would have a longer lifespan.

Average lifespan
Status: wild: 10-12 years.

Salvelinus confluentus, whether in a lake or stream setting, become sexually mature between four and ten years old (Bjornn, 1991; USFWS, 1998). Bull trout begin to spawn in the late part of August or early September and often lasting through October (Bjornn, 1991). Spawning times for specific populations is governed largely by water temperature. Generally, however, spawning activities are triggered when the water temperature drops below 10 degrees Centigrade (Bjornn, 1991).  Many populations of bull trout are migratory in nature whether they are of the lake or river form. Those population segments living in lakes will migrate up natal rivers as spawning is not possible in still water. Those segments that are river dwelling will often migrate within the system from smaller headwaters to larger mainstream sections of river (Bjornn, 1991).

As is typical of all trout and salmon, the female, after finding a suitable spawning area, fans a section of gravel substrate thereby producing a large depression in the stream bed. After this process is complete a male bull trout (usually only one) will fertilize eggs deposited by the female. Depending on the size of the individual, fecundity can vary. For average size bull trout around 5000 eggs can be typical (Nelson and Paetz, 1992), however many more can be found in larger specimens and some bull trout in the fifteen pound range have been documented as having approximately 12,000 eggs (Bjornn, 1991).

It is possible for male bull trout to spawn with more than one female. Although the species is not monogamous, some evidence has been documented that male and female bull trout can pair up during migration (Bjornn, 1991).

Range number of offspring: 200 to 12,000-13,000.

Average number of offspring: 5000.

Range gestation period: 100 to 120 days.

Average age at sexual or reproductive maturity (female): 4-10 years.

Average age at sexual or reproductive maturity (male): 4-10 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization (External ); broadcast (group) spawning; oviparous

Parental Investment: no parental involvement

Spawns in late summer or fall, with falling temperatures between 5 C and 9 C. Eggs hatch in late winter or early spring. Fry emerge from gravel in April or May. Most information indicates that sexual maturity is attained in 5-7 years (also reported as 4-5 years). May spawn each year or in alternate years. Spawning populations may comprise four or more year classes, though one or two year classes may dominate. See Rieman and McIntyre (1993).

Over the past century habitat degradation, introduction of non-native fishes and overfishing has caused the bull trout to become threatened across most of its range (Bjornn, 1991). S. confluentus is currently extinct in California with all of the native stock gone (USFWS 1998). Throughout its range, bull trout have been extirpated from many streams once inhabited by the species (Bjornn, 1991). Viable populations do exist, but the population density of the species has been severely diminished.

It is imperative at this stage that measures continue to be taken to ensure the future of S. confluentus as a unique, indigenous western species. Some steps have already been implemented to reduce mortality, such as habitat restoration and protection, catch and release fishing in some areas, and prohibitions on fishing in others.

Habitat degradation, facilitated largely through increased siltation due to unsound land use practices needs to be further curtailed. The bull trout is highly intolerant of polluted waters and likewise requires the coldest and cleanest water of all salmonids (USFWS, 1998). Implementation of better land use practices in or around drainages that contain bull trout are vital to the existence of the species. According to the IUCN red list the species is vulnerable and has seen a decline of at least 20% over the last ten years, primarily for the reasons stated above. A reduction of an additional 20% is projected for the next ten years if the current trend continues (IUCN, 2000).

In some areas where populations have been affected by anthropogenic impacts, bull trout culture in hatcheries could prove to be a successful means of restoring the population (Bjornn, 1991).

US Federal List: threatened

IUCN Red List of Threatened Species: vulnerable

Year Assessed

• Needs updating

Assessor/s

Reviewer/s

Contributor/s

History

• 1994
  Indeterminate
  (Groombridge 1994)
• 1990
  Rare
  (IUCN 1990)
• 1988
  Rare
  (IUCN Conservation Monitoring Centre 1988)

Canada

Rounded National Status Rank: N3 - Vulnerable

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Ranges from extreme southern Yukon to northern California and northern Nevada; greatly reduced in range and numbers south of Canada, but many occurrences remain in the core of the range; many streams contain exotic congeners that compete for spawning females; trend over the past 10 years or three generations is relatively stable in the major portion of the range in British Columbia.

Current Listing Status Summary

Status: Threatened
Date Listed: 06/10/1998
Lead Region:   Pacific Region (Region 1)   
Where Listed: U.S.A., conterminous, lower 48 states

Status: Experimental Population, Non-Essential
Date Listed: 12/09/2009
Lead Region:   Pacific Region (Region 1)   
Where Listed: Clackamas River subbasin experimental population

Population detail:

Population location: Clackamas River subbasin and the mainstem Willamette River, from Willamette Falls to its points of confluence with the Columbia River, including Multnomah Channel
Listing status: EXPN

Population location: U.S.A., conterminous, (lower 48 states)
Listing status: T

For most current information and documents related to the conservation status and management of Salvelinus confluentus , see its USFWS Species Profile

Global Short Term Trend: Relatively stable (=10% change)

Comments: Trend over the past 10 years or three generations is relatively stable in the major portion of the range in British Columbia.

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: Hybridization appears to be a common problem where isolated or remnant resident populations overlap with introduced brook trout (spawning times and conditions are similar). Brook trout have been widely introduced and now occupy most basins inhabited by bull trout, though they often occupy different streams or stream reaches. Hybrids are likely to be sterile and experience developmental problems, and sometimes sharp declines in bull trout populations have occurred (Leary et al. 1993). In Montana, introduced brook trout progressively depressed a bull trout population. See Rieman and McIntyre (1993). In western Montana, Kanda et al. (2002) found that F1 hybrids can reproduce but they found no evidence of hybrid swarms in which all individuals are of hybrid origin. Because hybridization generally involved female bull trout and male brook trout, they concluded that hybridization represents greater wasted reproductive effort for bull trout than for brook trout.

Introduced brown trout and rainbow trout have been associated with bull trout declines, apparently due to competitive interactions; lake trout may have a negative impact on bull trout, due to predation by lake trout on juvenile bull trout, probable competitive interactions, and increased harvest associated with increased fishing pressure for lake trout (see Rieman and McIntyre 1993). Lake trout can displace bull trout and may prevent bull trout from becoming established in certain low elevation lakes (Donald and Alger 1993).

Stocked, hatchery-reared steelhead that do not migrate to the ocean (residual steelhead) sometimes migrate over 12 km upstream from their release point and may move into areas occupied by threatened stocks of bull trout (McMichael and Pearsons 2001). Residual steelhead could pose a threat through ecological interactions.

Bull trout are threatened by activities that damage riparian areas and cause stream siltation; logging, road construction, mining, and overgrazing may be harmful to spawning habitat. This species is very sensitive and severely impacted by siltation of spawning streams. Timber harvest and associated activities may have negative impacts on stream channels through sedimentation and/or increasing flooding or scour events (Rieman and McIntyre 1993).

Habitat fragmentation may be a problem, but it is unclear whether the fragmented distribution is natural due to specific habitat requirements or caused by human impacts (Rieman and McIntyre 1993). Some migratory populations have been virtually eliminated by water diversions or habitat disruption (e.g., in the Bitterroot basin) (Rieman and McIntyre 1993).

Passage through screens of water diversion structures has been a problem in some areas, but currently specified screen regulations for Pacific Northwest salmonid fry apparently do not need to be modified for bull trout fry (Zydlewski and Johnson 2002).

Climate change (warming) is a potential threat because it would decrease the amount of suitable habitat (see Rieman and McIntyre 1993).

Extirpation in California probably resulted from two factors: 1) interaction with the introduced brown trout, and 2) indirect effects resulting from the loss of the McCloud River spawning population of chinook salmon; loss of the massive influx of nutrients provided by dying salmon altered the character of the stream (Minckley and Deacon 1991).

Overharvest and illegal harvest are past and present threats, contributing to population reductions and threatening existing small populations. In response, Idaho, Montana, Oregon, and Washington have instituted strict harvest guidelines.

Electrofishing can be harmful to individual survival and reproduction (see management section).
In the Klamath River basin, bull trout are threatened by habitat degradation caused by livestock grazing, timber harvest, and water withdrawals; drought has aggravated the situation and existing land and water management and regulatory mechanisms have failed to protect populations and habitat; non-native brook trout also are a serious threat because of possible hybridization and competition; probably fewer than 5000 individuals remain in 7 fragmented populations (Fisheries Action News, Winter 1994). Each of the seven populations is at a moderate to high risk of extirpation (USFWS 1997).

Columbia River population segment is threatened by habitat degradation, passage restrictions at dams, and competition from non-native lake and brook trout.

For further information, see the threats section for individual population segments of bull trout.

Vulnerable (VU) (A2e)

Management Requirements: Management efforts should include (1) habitat improvement such as the creation of instream structures that provide pockets of slow water favorable to juveniles and (2) protection from introduced brook trout (Spahr et al. 1991). See Thomas et al. (1993) for information on habitat management for this and other at-risk fish species in the Pacific Northwest.

Based on reproduction by F1 hybrids, Kanda et al. (2002) concluded that it would be appropriate to remove brook trout and brook trout/bull trout hybrids from streams occupied by bull trout.

A draft recovery plan for three of the five distinct population segments (Klamath, Columbia, and St. Mary-Belly Rivers) was available in late November 2002 (http://pacific.fws.gov). Recovery will require reducing threats to long-term population persistence, maintaining multiple interconnected populations across diverse habitats, and preserving the diversity of life-history strategies (e.g., resident or migratory forms, emigration age, spawning frequency, local habitat adaptations). See the draft recovery plan for further details.

Rieman and Allendorf (2001) concluded that cautious long-term management goals for bull trout populations should include an average of at least 1,000 adults spawning each year. Where local populations are too small, managers should seek to conserved a collection of interconnected populations that is at least large enough in total to meet this minimum (Rieman and Allendorf 2001). Also, full expression of life history variation and the natural processes of dispersal and gene flow should be provided (Rieman and Allendorf 2001).

Management Research Needs: Rieman and McIntyre (1993) listed the following research priorities: determine the range of conditions (especially temperature) tolerated by stable populations; determine the role of habitat disruption in the displacement of bull trout by brook trout; determine the effects of constructing barriers to limit the expansion of brook trout; investigate metapopulation structure and dynamics and dispersal; investigate the role of environmental variation in local extinction risk; investigate the role of the resident and migratory forms in population persistence, and determine the interactions between these forms; explore simulation methods for estimating extinction risks.

Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: Protected in Glacier National Park and Bob Marshal Wilderness, but brook trout, and habitat degradation outside these areas, still pose threats. Special rule allows for take of bull trout within the Columbia River population segment if in accordance with applicable state fish and wildlife conservation laws and regulations (USFWS 1997).

For the Klamath River distinct population segment (DPS), USFWS (2002) proposed critical habitat in approximately 476 kilometers (296 miles) of streams and 13,735 hectares (33,939 acres) of lakes and marshes in Oregon. For the Columbia River DPS, the proposed critical habitat designation totals approximately 29,251 km (18,175 mi) of streams and 201,850 ha (498,782 ac) of lakes and reservoirs, which includes: approximately 14,416 km (8,958 mi) of streams and 83,219 ha (205,639 ac) of lakes and reservoirs in the State of Idaho; 5,341 km (3,319 mi) of streams and 88,051 ha (217,577 ac) of lakes and reservoirs in the State of Montana; 5,460 km (3,391 mi) of streams and 18,077 ha (44,670 ac) of lakes and reservoirs in the State of Oregon; and 4,034 km (2,507 mi) of streams and 12,503 ha (30,897 ac) of lakes and reservoirs in the State of Washington.

Needs: "Conservation of bull trout will require maintenance or restoration of multiple, high-quality, connected habitats distributed throughout conservation areas, which in turn should be distributed throughout the species' range" (Rieman and McIntyre 1993). Effective conservation of the species and its inherent diversity requires an interregional appoach (Rieman and McIntyre 1993).

None known

None known

Positive Impacts: research and education

gamefish: yes; aquarium: public aquariums