Oregon Tui Chub tion and abundance of this subspecies. No recent (Gila bicolor oregonensis) surveys of habitats occupied by the Lakes tui chub are known. Thus, any additional, recent The Oregon Lakes tui chub, as defined here, is factors influencing its status are unknown. The endemic to the Abert Basin of south-central introduction of non-native fishes also threatens the Oregon (Bills 1977). Remaining populations are continued existence of this subspecies. The type classified by the State of Oregon as vulnerable. locality population, at XL Spring, is particularly The American Fisheries Society lists the Oregon vulnerable to loss because of its restricted habitat. Lakes tui chub as a species of special concern (Williams and others 1989), although they use the Summer Basin Tui Chub common name XL Spring tui chub for this form. (Gila bicolor spp.) Distribution and Status The Summer Basin tui chub is endemic to springs and outflows in the Summer Basin of south- The Oregon Lakes tui chub complex, as originally . The form was considered of described by Snyder (1908), consisted of tui chub uncertain taxonomic status and possibly extinct by populations in five isolated basins of south-central Bills (1977) during a thorough review of the Oregon: Silver, Summer, Abert, Alkali, and Oregon tui chub complex in southern Oregon. Warner. The pioneering work of Bills (1977) Summer Basin tui chubs were rediscovered in demonstrated that morphological divergence had 1985. This subspecies is listed as a Cl Candidate occurred among these long-isolated populations by the U.S. Fish and Wildlife Service and as en- and he recognized that the complex of tui chubs dangered by the American Fisheries Society actually consists of four subspecies. Only popula- (Williams and others 1989). tions in the Abert Lake Basin are retained in Gila bicolor oregonensis. They occur in XL Spring to the Distribution and Status north of Abert Lake and in the Chewaucan River (map 4.53). Abert Lake is, in general, fishless but Historically, the Summer Basin tui chub occurred records of chubs exist, presumably in areas of at various localities within Summer Basin, includ- spring or river inflow (Snyder 1908). No changes ing springs at the Post Office, Ana between historic and current distributions are River, and source springs of the (map known although the Abert Lake Basin has not 4.54) (Snyder 1908). Collections in these localities been adequately sampled. during the 1960s and 1970s indicated divergence from the form that was native to the Summer Habitat Relationships Basin, a result of numerous applications of fish toxicants and transplants of chubs from adjacent In general, tui chubs occupy a wide variety of basins (Bills 1977). The native form was consid- habitats (Moyle 1976). In the Abert Lake Basin, ered extinct until rediscovered from a small, previ- the Oregon Lakes tui chub inhabits springs, rivers, ously unsampled spring system on the west side of and ditches. The Oregon Lakes tui chub is absent the Summer Lake bed in 1985.9 The subspecies from higher gradient portions of the Chewaucan now occupies a small portion of its historic range. River system. Habitat Relationships Key Factors Influencing Status Habitat relationships are poorly known because Agricultural practices, including ditching and habitats in the Summer Basin have been greatly diverting stream flows as well as livestock grazing, modified and the fish were eliminated from much are the principal factors influencing the distribu-

'Personal communication. 1995. C.E. Bond and J.E. Williams, Oregon State University, Corvallis, Oregon. Personal communication of unpublished data.

Aquatics Map 4.53--Historical and current distribution of Oregon Lakes tui chub.

1304 A q u at ic s

Map 4.54--Historical and current distribution of Summer Basin tui chub.

Aquatics of its range prior to surveys. Historically, the Refuge, Washoe County in Nevada, and Piute and Summer Basin tui chub appears to have occurred Guano creeks, Lake County in Oregon (Hubbs in a variety of spring and creek systems in the and Miller 1948, Williams and Bond 1981). basin. Sheldon tui chubs apparently are extremely rare in Guano Creek and have only been collected there Key Factors Influencing Status twice.10

Fishes in Ana Springs, its outflow and associated Habitat Relationships reservoir have been repeatedly poisoned to rid the area of nongame fish in favor of game species. The Sheldon tui chub occurs in those portions of Such efforts along with subsequent transplants of Fish and Piute creeks described as small, turbid tui chubs from adjacent basins apparently elimi- desert streams with abundant aquatic and riparian nated the native tui chub from the Ana River vegetation. During drought years, the chubs may system. Additional transplants of non-native fishes be restricted to isolated pools in intermittent appear to have eliminated the native form from stream sections. The Sheldon tui chub typically is springs and ditches in the Post Office area. The absent from downstream reaches, which often dry remaining population occurs in small, isolated during summer months. When water is abundant, springs in the southern portion of Summer Basin. chubs also may occur in terminal lakes and reser- During brief surveys in 1985, habitats of the voirs of these streams as suggested by the discovery remaining population were threatened by livestock of skeletal remains of Sheldon tui chub in Swan grazing and water diversions. It is uncertain Lake Reservoir, which is the terminal water body whether the subspecies continues to persist in its on Fish Creek (Williams and Bond 1981). restricted habitat. Primary threats include habitat degradation by livestock, water diversions, and Key Factors Influencing Status introductions of non-native species. Drought, fire, and other disturbances also could threaten this All streams where the Sheldon tui chub occur subspecies. could be described as "marginal" in reference to their small and often intermittent nature. Grazing Sheldon Tui Chub by livestock apparently has limited the amount of available habitat by reducing riparian vegetation (Gila bicolor eurysomd) and limiting soil water retention, which leads to The Sheldon tui chub was described from speci- drying of additional stream segments during mens collected from Fish Creek, Washoe County, summer and autumn (Williams and Bond 1981). Nevada (Williams and Bond 1981). This subspe- Reductions in stream flow due to overgrazing and cies, which occurs sporadically in the mostly arid water diversion appear to be the primary threat to Guano Basin of southeastern Oregon and north- this subspecies. Because of the species restricted western Nevada, is listed as a species of special range and small habitat size, such factors will concern by the American Fisheries Society exacerbate risks associated with environmental (Williams and others 1989). stochasticity, such as drought. Although intro- duced fish have not been documented from water Distribution and Status inhabited by the Sheldon tui chub, any introduc- tions could be detrimental to this subspecies. The Sheldon tui chub is restricted to isolated waters of the Guano Basin of southeastern Oregon '"Personal communication. 1995. J. Williams, Bureau of Land and northwestern Nevada (map 4.55). Within Management, Boise, . Personal communication of Guano Basin, the subspecies has been reported unpublished data. from Fish Creek on the Sheldon National Wildlife

Aquatics Hutton Tui Chub (Gilo, bicolor spp.) the Bonneville Basin into the Snake Basin. Its current distribution in Idaho may, in part, also be due to its The Hutton tui chub, collected as early as 1908, release as a bait fish. The leatherside chub is presendy has been found in only two surface flow areas of listed by the BLM as a sensitive species, and by die Hutton Spring, Oregon. The Hutton tui chub was Idaho Department of Fish and Game as a species of listed as threatened in 1985 by the U.S. Fish and special concern, Category C undetermined status. Wildlife Service. It is also considered threatened by the American Fisheries Society (Williams and Distribution and Status others 1989). In 1934, Carl Hubbs made die first reported collec- Distribution and Status tion of leatherside chub in Idaho.11 The leatherside chub was collected in the 1970s in die Raft River Hutton tui chubs still inhabit their historical and Goose Creek tributaries of the Snake River and locations (map 4.56). The subspecies is restricted the Litde Wood River, all in Idaho (map 4.57).12 In to Hutton Spring and a small nearby spring in the 1995, leadierside chubs were collected from Trapper, Alkali Lake Basin of south-central Oregon (Bills Goose, and Dam creeks, all part of the Goose 1977). In 1977, population estimates were 300 at Creek drainage near the Nevada-Utah border.13 Hutton Spring and 150 at the unnamed spring. Otherwise, because of a lack of surveys, their current status is unknown. Habitat Relationships The Hutton tui chub lives its entire life in spring Habitat Relationships habitats. Little is known about their habitat re- Little is known about the habitat requirements of quirements, with the exception that dense aquatic leatherside chub. They typically occur in cool to vegetation is needed for spawning and rearing of cold creeks and rivers, with adults residing in pools young. and riffles and young inhabiting brushy, quiet pockets near the shoreline. Water quality ranges Key Factors Influencing Status from clear to occasionally turbid. Leatherside chub The habitat of the Hutton tui chub, along with that are typically found associated with gravel substrate, of the Foskett speckled dace, are die most restricted but they also use all substrate sizes. of any fish in the assessment area. Because of their limited distribution and small population size, Key Factors Influencing Status Hutton tui chubs are at risk A hazardous waste The most significant threat to the leatherside chub dump at Alkali Lake threatens to contaminate sur- is loss of habitat caused by development of irriga- face floodwater, groundwater, and air at Hutton tion projects in the 1930s. However, habitat losses Spring. Persistence of the Hutton tui chub is threat- have and continue to occur from overgrazing of ened by catastrophic events to spring sources, pollu- livestock, mining, timber harvest, and road con- tion from toxic chemicals, vandalism, introduction struction.14 Predation and competitive interactions of non-native species, and no natural sources of from the stocking of exotic game species may also recolonization. affect leatherside chub populations. However, the threat from these introductions is not known. Leatherside Chub (Gila copei) The native range of the leatherside chub in Utah and "University of Michigan Museum of Zoology. 1995. Unpub- lished collection records. Wyoming consists of die eastern and southern parts of die Bonneville Basin in rivers draining into die "Personal communication. 1995. F. Partridge, Idaho Depart- ment of Fish and Game, Jerome, Idaho. Great Salt Lake. In Idaho, the species is presumed to "Personal communication. 1995. B. Horton, Idaho Depart- occur naturally as a result of pluvial discharges from ment of Fish and Game, Boise, Idaho. '^Personal communication. 1995. F. Partridge, Idaho Depart- ment of Fish and Game, Jerome, Idaho.

Aquatics Map 4.55--Historical and current distribution of Sheldon tui chub.

Aquatics Map 4.56--Historical and current distribution ofHutton tui chub.

A q u at ic s 1309

Map 4.57--Historical and current distribution of leatherside chub.

1310 Aquatics Foskett Speckled Dace Key Factors Influencing Status (Rhinichthys osculus spp.) Foskett speckled dace need adequate surface flows The Foskett speckled dace is an undescribed sub- free of non-native species to persist. Because of the species restricted to springs in the Coleman Valley restricted flows, habitats can be easily disturbed by of southeastern Oregon. The dace is federally visitor use, livestock grazing and reduction of listed as threatened and as vulnerable by the State riparian vegetation. Habitats also could be dis- of Oregon. The American Fisheries Society also turbed by significant increases in vegetation, lists the Foskett speckled dace as threatened which could choke the spring system or reduce (Williams and others 1989). surface flows. Because of its small size, Foskett Spring could be easily disturbed by changes in Distribution and Status flows resulting from surface or subsurface distur- bance. Both springs are fenced and protected from The Foskett speckled dace historically was known livestock grazing by the BLM. only from Foskett Spring, located along the west side of Coleman Lake bed in Lake County, Lost River Sucker (Deltistes luxatus) Oregon (map 4.58) (Bond 1974). Coleman Lake is dry except during years of exceptional rainfall. The Lost River sucker, one of four native suckers During 1979, dace from Foskett Spring were in the of California and Oregon, transplanted into Dace Spring, located 1.5 kilome- was the most important food fish of Modoc and ters south of Foskett Spring to create a second Klamath tribes in the Klamath Lake Region population. The population in Dace Spring had (Andreasen 1975b; USFWS 1993b). As a result of reproduced and appeared to be established low numbers, reduction in spawning and rearing (Williams and others 1990), but has recently habitat, and poor adult recruitment, the U.S. Fish become extirpated.15 Although the watershed that and Wildlife Service listed the Lost River sucker as contains Coleman Lake extends into Nevada, the endangered in 1988. In 1994, 185,000 hectares of dace does not occur in that state. Total population stream, river, lake, and shoreline were proposed as size is approximately 2,000 in Foskett Spring critical habitat for the Lost River sucker by the (Bond 1974). U.S. Fish and Wildlife Service.

Habitat Relationships Distribution and Status Foskett Spring is a small, cool-water (approxi- The Lost River sucker historically occurred in the mately 16° to 17° C) spring. The Foskett speckled Lost River and upper systems of dace are abundant in the small spring pool and northern California and southern Oregon, includ- associated outflow until surface flow disperses and ing Clear, Tule, Lower Klamath, Sheepy, Agency, disappears near the edge of Coleman Lake. The and Upper Klamath lakes and their tributaries species were also abundant at Dace Spring, includ- (map 4.59) (USFWS 1993b). Currently, Lost ing an adjacent cattle trough located just outside River sucker populations and available habitat the fenced area. No other fish has been reported have been greatly reduced. Lost River suckers from Coleman Valley. currently are found in Upper Klamath and Tule lakes and Clear Lake Reservoir, with possible populations in Sheepy Lake and Iron Gate Reser- "Personal communication. 1995. Alan Munhall, Bureau of Land Management, Lakeview, Oregon. voir. Recruitment of juvenile Lost River suckers to adult classes is poor, resulting in populations of older suckers and few new spawning individuals (USFWS 1993b).

Aquatics "1- Map 4.58--Historical and current distribution of Foskett speckled dace.

Aquatics Map 4.59--Historical and current distribution of Lost River sucker.

Aquatics Habitat Relationships mented large Warner sucker populations, includ- ing major spawning runs of "redhorse" up tribu- . Suckers, as bottom dwellers, are sensitive to low taries as recently as the 1930s (Andreasen 1975b). near-bottom dissolved oxygen levels (Buettner and Three relatively permanent lakes, Hart, Crump, Scoppetone 1990). In spring and summer, they and Deep, provide primary habitat for the Warner seek refuge from poor water quality conditions sucker (Williams and others 1990). During wet and can be found at spring fed areas in lakes. years, the species also occurs in ephemeral lakes in During spawning, adults move from lake habitats the north end of the valley. Five perennial streams to larger tributary streams or adjacent spring provide spawning habitat: Snyder, Honey, Deep, systems. Adult Lost River suckers spend little time Twelvemile, and Twentymile creeks (Coombs and in spawning tributaries of lakes. Juveniles are others 1979). All these habitats are in south- found along the bottom of gently sloping lake central Oregon, except a small portion of shorelines, in water less than 50 centimeters in Twelvemile Creek, which flows from California depth. into Nevada and then north into Oregon. Warner suckers have been collected from the Nevada and Key Factors Influencing Status Oregon portions of Twelvemile Creek but not the Loss of spawning and rearing habitat has been the upstream, higher-gradient California sections. largest impact on Lost River sucker populations. During extreme drought conditions of the early Dams, livestock grazing, ditching, tilling, diking, 1990s, some Warner suckers were transplanted and loss have reduced historical habitat by from drying habitats in Warner Valley to an area up to 90 percent. Agriculture and forestry prac- near Summer Lake, Lake County, Oregon, where tices have increased nutrients and chemical con- diey still persist. taminants, thereby reducing dissolved oxygen levels, disrupting food chains, and minimizing Habitat Relationships aquatic organism survival. Introductions of non- Historically, the Warner sucker probably inhabited native fish species have increased predation on a wide variety of marsh, slough, lake, and stream larval Lost River suckers (USFWS 1993b). Low habitats in the valley. Studies during the 1970s populations, habitat fragmentation, poor adult (Coombs and others 1979) documented the pres- recruitment, loss of spawning and rearing habitat, ence of both lake and resident stream populations and water quality degradation threatens the persis- of Warner suckers. The species also occurs in larger tence of the Lost River sucker. irrigation ditches and shallow, ephemeral lakes.

Warner Sucker Key Factors Influencing Status (Catostomus warnerensis) Historically, the lakes and streams of Warner The Warner sucker is endemic to the Warner Valley were interconnected by slough and marsh Basin of south-central Oregon and an adjacent areas which allowed Warner suckers broad access area of Nevada. The species was federally listed as to a variety of habitats. Draining of threatened by the U.S. Fish and Wildlife Service in coupled with installation of numerous irrigation 1985. The state of Oregon also recognizes the diversion structures on lower reaches of tributaries species as threatened. gready fragmented the distribution of the species and precluded access to many historic spawning Distribution and Status areas as well as access to inflowing streams as lakes dried during drought periods. During 1992, for The Warner sucker historically was restricted to example, Hart Lake completely dried and nearly lake habitats and their tributary streams in Warner eliminated die species. Water diversion practices Valley (map 4.60). Accounts of early settlers docu-

Aquatics Map 4.60mHistorical and current distribution plus introduced sites of Warner sucker.

Aquatics also can be detrimental to any juveniles that drift tonwood Reservoir, Dog Lake, and Goose Lake. downstream and are diverted into fields. Degrada- Spawning fish migrate from Goose Lake into tion of riparian zones also has reduced this species' Lassen, Willow, Thomas, Dry, and Cottonwood numbers. Bank erosion has widened channels, creeks (King and Hansen 1966; also, see previous reduced cover, and increased sedimentation rates. footnote). The actual abundance of Goose Lake Large populations of non-native species, particularly suckers is unknown, although they are locally centrarchids and ictalurids, occur in lake habitats and common in many streams where they occur. In appear to prey on young Warner suckers as they 1992, the population in Goose Lake was elimi- return from spawning areas (Williams and others nated, at least temporarily, when drought caused 1990). During 1987 and 1989 surveys in Warner the lake to dry completely. However, this was not Valley, suckers comprised only 2.5 percent of the first time the lake had become desiccated. fishes collected, whereas introduced crappie Recolonization is expected to occur naturally. (Pomoxis spp.) and brown bullheads (Ameiurus nebulosus) accounted for 38.0 percent (Williams Habitat Relationships and others 1990). Poor recruitment continues to threaten the existence of the Warner sucker. Very little specific habitat information is available Spawning areas are very limited because of poor on the Goose Lake sucker. Two life history pat- access as described above. The relatively small terns are present in the Goose Lake Basin: a resi- number of larvae produced each year may fall prey dent stream form, and a lake form that ascends to introduced predatory fishes. Overgrazing by tributary streams during spring spawning runs. livestock reduces riparian vegetation and further Goose Lake is a large, shallow, and alkaline natural intensifies effects during drought periods. lake where bottom sediments are easily suspended by winds that create turbid conditions. Lake Goose Lake Sucker temperatures vary with ambient conditions and range from 1° to 24° C (Johnson and others 1985). (Catostomus occidentalis Spawning habitat in lower Willow Creek is charac- lacusanserinus) terized by a complex of cobble-pebble-gravel with 17 The Goose Lake sucker, a subspecies of the more moderate to swift current. In streams during widespread Sacramento sucker (Catostomus summer, Goose Lake suckers seem to prefer pool occidentalis), is endemic to the Goose Lake Basin habitats, with young of year rearing in shallows. of south-central Oregon and northeastern Califor- nia. The Goose Lake sucker is a Forest Service Key Factors Influencing Status Region 6 sensitive species, and a State of Oregon Historically, Goose Lake provided refuge to a sensitive species. relatively diverse native fish fauna free of non- native species that occur in tributary streams and Distribution and Status elsewhere. Lower reaches of major tributary The subspecies is found in Goose Lake and many streams served as refuges to lake-dwelling Goose of its larger tributaries (map 4.61) (Moyle and Lake suckers during drought periods. Irrigation others 1989). Goose Lake suckers were collected diversions and physical barriers disrupted this during the 1980s from Corral, Long Branch, pattern and compounded risk to this subspecies Badger-Cloud, Davis, Lassen, and Willow creeks during periods of naturally reduced water avail- in Modoc County, California, and Augur, Bauers, ability. Many stream habitats have been degraded Thomas, Cox, Cottonwood, Fall, Dry, Drews, by agricultural practices. Overgrazing by livestock Dog, and Hay creeks in Lake County, Oregon.16 and resulting loss of riparian vegetation, increased The subspecies also has been collected from Cot- ''Personal communication. 1995. J. Williams, Bureau of Land 16 Management, Boise, Idaho. Personal communication of Personal communication. 1995. J. Williams, Bureau of Land unpublished data. Management, Boise, Idaho.

Aquatics Map 4.61-- Historical and current distribution of Goose Lake sucker.

Aquatics water temperature, and increased sedimentation Lake system, primary spawning habitats include are common problems along the lower reaches of the Williamson, Sprague, and Wood rivers. The Goose Lake tributaries. Non-native fishes occur in species has suffered large reductions in numbers many stream systems occupied by the Goose Lake and range (Andreasen 1975b; USFWS 1993b). sucker, but the extent of their impact on Goose Remaining populations appear to be restricted to Lake sucker populations is unknown. In 1994, a Upper Klamath Lake and tributaries, Klamath new non-native species, the fathead minnow River downstream to Iron Gate Reservoir, and (Pimephales promelas), was collected in Willow Clear Lake Reservoir and its primary tributary, Creek.18 The effect of this species on the native Willow Creek. The species also may occur in fish fauna is uncertain, but fathead minnows Gerber Reservoir, which may be the result of an dominate in many parts of the nearby Klamath introduction (USFWS 1993b). Riverine spawning Basin, where they have been broadly introduced. of the Upper Klamath Lake population is re- Stream populations also may face increased risk stricted to the lowermost reaches of the from stochastic events because of their small popu- Williamson and Sprague rivers because of a diver- lation size. sion dam on the at Chiloquin, Oregon. Shortnose Sucker (Chasmistes brevirostris) Habitat Relationships The shortnose sucker is endemic to the Klamath Members of the family Catostomidae are primarily Basin of south-central Oregon and northern bottom-dwelling fishes although the nearly termi- California. They were a primary food source for nal mouth of the shortnose suggests adaptation for the Klamath Indians and provided a popular sport more mid-water lake habitats. During recent years, fishery on tributary streams until populations occurrences in lake habitats appear to be primarily decreased substantially during the early 1980s. influenced by adults seeking improved water They are federally listed as endangered by the U.S. quality conditions. Adult shortnose suckers spend Fish and Wildlife Service because of low popula- relatively little time during spawning periods in tion numbers, reduction in spawning and rearing riverine habitats. Larvae are surface oriented and habitat, and poor recruitment. The species also is tend to occur in shallow, shoreline habitats. listed as endangered by the State of Oregon. In 1994, the U.S. Fish and Wildlife Service (U.S. Key Factors Influencing Status Government 1994) proposed critical habitat for Factors leading to the decline of the shortnose the shortnose sucker that consists of 185,000 sucker are multiple and complex. Like the Lost hectares of stream, river, lake, and shoreline areas. River sucker, the lack of recruitment is probably the greatest threat to its continued existence. The Distribution and Status influence of numerous non-native fishes in Upper Shortnose suckers are endemic to the Upper Klamath Lake is presumed to be negative because Klamath Basin and were known to be locally of the potential for competition or predation on abundant in lake habitats and, during spawning larval and juvenile suckers. Non-native species runs, in tributaries (map 4.62). Documented may be a primary factor causing the lack of re- occurrences include the Upper Klamath and cruitment observed in Upper Klamath Lake and Agency lakes system and the Lost River system, other lake habitats. Draining of marshes, including Tule Lake. Within the Upper Klamath channelization, and dams have been major factors contributing to loss of habitat and the decline of "Personal communication. 1995. Paul Chappell, California the shortnose sucker. Replacement of wetlands Department of Fish and Game, Redding, California.

Aquatics Map 4.62-- Historical and current distribution ofshormose sucker.

Aquatics surrounding the lakes with farms has resulted in (Klamath largescale, Lost River, and shortnose) in pollution and hypereutrophication of lake habitats the Klamath Basin have declined greatly compared with resulting fish kills from poor water quality. with their historic abundance. Klamath largescale Low population numbers, habitat fragmentation, suckers have been virtually eliminated from the poor adult recruitment, loss of spawning and Lost River system since at least the early 1970s rearing areas, and water quality degradation (Contreras 1973). threaten the persistence of this species. The risk increases as the decrease in genetic diversity from Habitat Relationships habitat fragmentation makes populations more susceptible to environmental change. Also as Upper Klamath and Agency lakes harbor lake- spawning populations become smaller and the dwelling populations of Klamath largescale suckers amount of spawning area decreases, the species that ascend major tributaries during spring for becomes more susceptible to hybridization and spawning. Unlike the Lost River and shortnose introgression with remaining Lost River and suckers, however, Klamath largescale suckers also Klamath largescale suckers, which spawn in the occur as resident riverine populations in the same areas. Williamson, Sprague, and Sycan rivers. While adult largescale suckers are oriented to bottom Klamath Largescale Sucker substrates of lakes and rivers, larvae are surface oriented and are found over gravel and cobble (Catostomus snyderf) substrates of rivers (Buettner and Scoppettone The Klamath largescale sucker is one of four 1990). In lakes, juvenile Klamath largescale suck- members of the family Catostomidae native to the ers tend to congregate along the bottoms of gently Klamath Basin of south-central Oregon and sloping shorelines. northern California. The species provided a staple food for the Klamath Indians and a major sport Key Factors Influencing Status fishery as recently as 1980. It occurs in many of The historic marshes and interconnected water- the same habitats and shares many of the same ways common to the Klamath and Lost rivers have threats as the shortnose and Lost River suckers. been nearly completely modified and replaced by The Klamath largescale sucker is classified by major irrigation projects. These projects have Region 6 of the Forest Service as a sensitive spe- drained wetlands, channelized streams, and di- cies. verted large amounts of water for irrigation. Nearly one-third of the wetlands in the Klamath Distribution and Status Basin were eliminated by the Klamath Reclama- The Klamath largescale sucker is native to the tion Project and many more areas were inundated Upper Klamath Lake drainage in south-central by reservoirs. Including degradation and loss from Oregon and to the Lost River system of Oregon intensive grazing by livestock, ditching, tilling, and California (map 4.63) (Andreasen 1975b; and diking, total wetland loss approximates 75 to Moyle and others 1989). Within the Upper Kla- 90 percent of historical extent. As a result of these math Lake system, the species is known from factors, habitats have been fragmented, access to Upper Klamath Lake, Agency Lake, Williamson historic spawning areas has been blocked, and River, Sprague River, Sycan River, Wood River, remaining lakes have suffered from hypereutro- and Sevenmile, Fourmile, Odessa, and Crystal phication and massive blooms of toxic blue-green creeks. Klamath largescale suckers also may occur algae. Modified habitats in the Klamath Basin now in the Klamath River between Upper Klamath support large numbers of non-native fishes, which Lake and Copco Reservoir. Populations of all the cause further decline in native sucker numbers lake-dwelling and big river sucker species through predation on young. The Lost River,

1320 Aquatics Map 4.63-- Historical and current distribution of Klamath largescale sucker.

Aquatics 1321