shortnose, and Klamath largescale suckers are all at risk because of lack of recruitment and adult susceptibility to hybridization and introgression among the species. As populations become smaller and spawning areas become increasingly modified and restricted in area, the likelihood of hybridization increases. Wood River Bridgelip Sucker (Catostomus columbianus hubbsf) The native range of the bridgelip sucker (Catostomus columbianus) in the assessment area is the Snake River drainage downstream from Shoshone Falls, Idaho and the Columbia River drainage to British Columbia. The Wood River in Idaho supports an isolated population that is "nearly 100 percent distinct" from other bridgelip sucker populations and has been described as a discrete subspecies (Smith 1966). Smith reported that the distinctness of the Wood River population suggests that it may warrant full species status upon further evaluation. The subspecies will be reviewed for listing by the Idaho Department of Fish and Game. The holotype of the Wood River bridgelip sucker was collected from Fish Creek, tributary to the Little Wood River, in 1934 by Carl Hubbs (Smith 1966). Other specimens were collected from the mainstem Big Wood and Litde Wood rivers. Electrofishing surveys of the Big Wood River since 1986 have captured bridgelip suckers that are presumed to represent this subspecies (Thurow 1990). 19 No comprehensive surveys have been completed. Therefore, the subspecies distribution and abundance are uncertain. Presumed distribution is shown in map 4.64. Habitat Relationships Little is known about the biology of the bridgelip sucker in the Wood River but it is believed to resemble that of other members of the species "Also personal communication. 1995. F. Partridge, Idaho Department of Fish and Game, Jerome, Idaho. (Simpson and Wallace 1978). In general, bridgelip suckers differ from most other suckers by inhabiting streams with colder, swifter water and rocky substrate (Scott and Grossman 1973). Fish likely mature after age-2 and spawn in late spring. Maximum size is about 25 centimeters. Key Factors Influencing Status The status of Wood River bridgelip suckers will likely be influenced by the same factors that affect the status of other native fish species in the Wood River drainage. Alteration of habitat by residential and agricultural development, including irrigation withdrawal, overgrazing by livestock, and introductions of non-native species are likely to be detrimental to the viability of this subspecies. Torrent Sculpin (Cottus rhotheus) The torrent sculpin inhabits rivers and streams in the Puget Sound and Columbia River drainages in the states of Oregon, Washington, Idaho, Montana, and in British Columbia (Maughan 1976). The torrent sculpin is listed as a sensitive species by die Forest Service in Region 1 and as a species of special concern by the Montana Department of Fish, Wildlife, and Parks. Historically, the torrent sculpin was found throughout tributaries of the mid- and upper Columbia River Basin, overlapping range with the shorthead sculpin. In Oregon and Washington, the torrent sculpin has been found in the Yakima, Entiat, and Palouse rivers and tributaries of the upper Deschutes River (map 4.65) (Wydoski and Whitney 1979). In Idaho, the torrent sculpin has been found in the Kootenai, Pend Oreille, Spokane, Clearwater, Salmon, St. Maries, upper Clark Fork, and Palouse river drainages and in the Snake River below Shoshone Falls (Simpson and Wallace 1978). MacPhee (1966) also found the torrent sculpin in Rochat Creek, a tributary to the St. Joe River. Aldiough the current status is unknown, the present range probably remains Aquatics
Map 4.64-- Current distribution of Wood River bridgelip sucker. Aquatics
Map 4.65-- Current distribution of torrent sculpin. Aquatics
similar to the historic range. When found, the torrent sculpin was in low numbers compared with the shorthead sculpin (MacPhee 1966). Habitat Relationships The torrent sculpin is primarily a benthic stream species but also occurs in lakes (Wydoski and Whitney 1979). In streams, they inhabit swift, cool, clear riffles with a stable bottom of scattered rubble, gravel, and boulder substrate (Simpson and Wallace 1978). Torrent sculpin were found only where rock substrate was present. Spawning, which occurs in riflfle areas with rubble or boulder substrate, starts in early spring and lasts to late April. Key Factors Influencing Status The torrent sculpin is probably susceptible to land use practices (for example, livestock grazing, road construction, and mining) and climatic events that degrade water quality and diminish its natural habitat. Pollution, increased water temperatures, and sedimentation are the major potential negative impacts to sculpin populations. Shorthead Sculpin (Cottus confusus) The shorthead sculpin inhabits rivers and streams in the Puget Sound and Columbia River drainages in the states of Oregon, Washington, Idaho, Montana, and in British Columbia (Bailey and Bond 1963). The shorthead sculpin is listed by the Forest Service as sensitive and by the Montana Department of Fish, Wildlife, and Parks as a species of special concern. In the assessment area, the shorthead sculpin is found in the upper reaches and tributaries of the Deschutes, Yakima, Wenatchee, and John Day river systems in the lower Columbia River Basin and the Snake, Spokane, Pend Oreille, and Kootenai River drainages in the mid and upper Columbia River Basin (map 4.66) (Bailey and Bond 1963). In the mid-columbia River Basin, the species has been collected in the Coeur d'alene and St. Joe river systems in Idaho (Maughan 1976), and in the upper Columbia in the Flathead, Little Blackfoot, and Blackfoot river systems in Montana and the Flathead River in British Columbia (Bailey and Bond 1963). In the Snake River drainage, the species occurs in the mainstem and tributaries of the Grande Ronde and Imnaha river systems in Oregon and the Clearwater, Salmon, Boise, Owyhee, Big Lost, and Little Lost rivers and Birch, Medicine, and Beaver creeks in Idaho (Maughan 1976). In 1994, surveys found shorthead sculpin in the upper Deschutes drainage in Oregon, the upper and lower Kootenai, Yaak, and Fisher rivers in Montana, the upper Yakima in Washington, and the upper and South Fork Coeur d'alene, and Little Lost rivers, and Birch Creek in Idaho. 20 Habitat Relationships The shorthead sculpin prefers riflfle areas and small coldwater rivers and streams (Bowler 1974). It has been collected in emergent grasses and slowmoving waters along shorelines and in backwaters. Spawning, which occurs in riffle areas with a rubble/boulder substrate, starts in early spring and lasts to late April. Key Factors Influencing Status The shorthead sculpin is probably susceptible to land use practices (for example, timber harvest activities, road construction, and mining) and/or climatic events that degrade water quality. Pollution, increased water temperatures, and sedimentation are the major potential negative impacts to sculpin populations. Once stream populations are eliminated, sculpin are poor recolonizers from adjacent areas as compared with trout. 20 Personal communication. 1995. Lori Leatherbury, Forest Service, Boise, Idaho. Aquatics
Map 4.66-- Current distribution of shorthead sculpin. iiii:i:iiiiii:iiiiiiiiiiiiiiiiiiiii: 1326 Aquatics
Pit Sculpin (Cottuspitensis) Pit sculpin were historically widespread in the Pit River system, from the Goose Lake Basin to the Sacramento River (Moyle 1976). In Oregon, the Pit sculpin is currently listed as sensitive by the Forest Service and BLM, and as a peripheral/rare species by the Oregon Department of Fish and Wildlife. In Oregon, the extent of the historical distribution of Pit sculpin in the Goose Lake Basin is unknown. However, the sculpin was recorded both historically and recently (1979), and can still be found, in a few tributaries of Goose Lake, specifically Cottonwood and Drews creeks (map 4.67) (Long and Bond 1979; ODFW 1992). Pit sculpin also were recorded historically in Thomas Creek, Oregon, but surveys in 1983 and 1988 yielded no sculpin. 21 The Pit sculpin has never been found in Goose Lake. In California, the Pit sculpin is still widespread throughout the Pit River system and has recently been found in Lassen, Gold, and Willow creeks, all tributaries of Goose Lake. The Pit sculpin, where found, tends to be rare. Habitat Relationships Pit sculpin are not known to migrate. They are a benthic species found mainly in small, cold water tributaries (Moyle 1976). They show a strong preference for riffle habitat with small gravel substrate (Moyle 1976). 22 In the winter, they use the interstices among large gravels and cobbles during near-freezing and ice formation periods. They occupy water that ranges in temperature from 6.5 C in March to 18.8 C in June. 23 21 Personal communication. 1995. J. Williams, Bureau of Land Management, Boise, Idaho. Personal communication of unpublished data. "Personal communication. 1995. J. Williams, Bureau of Land Management, Boise, Idaho. Personal sommunication of unpublished data. 23 Personal communication. 1995. J. Williams, Bureau of Land Management, Boise, Idaho. Personal communication of unpublished data. Factors Influencing Status The main reasons for the Pit sculpin's current status are its rarity and limited amount of available habitat. Pit sculpin are limited in their ability to recolonize a. stream once extirpated, this is especially true in the Goose Lake Basin because of the apparent lack of use of the lake. Because of their inability to recolonize, catastrophic events, loss of habitat, extreme droughts, and introductions of exotics could all lead to extirpation of individual stream populations. Extreme drought events and loss of stream habitat may have been factors limiting the current distribution of Pit sculpin in the Goose Lake Basin. Past management, such as livestock grazing, timber activities, and road building, has negatively affected sculpin habitat by increasing siltation (ODFW 1992). Loss of perennial, cool, spring-fed stream reaches, which act as refuge sites during extreme droughts, also has affected status. Slender Sculpin (Cottus tennis) The distribution of the slender sculpin is restricted to the Upper Klamath Basin in Oregon, upstream of Klamath Falls. The slender sculpin is listed as a sensitive species by Region 6 of the Forest Service and as a species of special concern by the American Fisheries Society (Williams and others 1989). The sculpin was historically distributed in the Upper Klamath and Agency lakes and their tributaries. Recorded distributions, between 1934 and 1976, are the lower Williamson and Sycan rivers, South Fork and mainstem Sprague and Wood rivers and Odessa, Denny, Crystal Camporee Spring, Crooked, Fort, and Sevenmile creeks (map 4.68) (Ford and Thomas 1993). The current status of slender sculpin is not well known, but sampling by Oregon State University and the Forest Service in 1992 found slender sculpins in sections of the Wood River and Larkin, Crystal, Crooked, and Fort creeks, and Fourmile Springs (Ford and Thomas 1993). Aquatics 432?'
Map 4.67-- Historical and current distribution of pit sculpin. 1328 Aq uatic s
Map 4.68-- Historical and current distribution of slender sculpin. Aquatics 1329
Habitat Relationships Slender sculpins reside in both lake and stream environments and use a variety of habitat types. They are found in detritus, mud, sand, gravel, and rubble substrate and occupy pools, riffles, and glides (Bond 1963). Similar to other sculpins, they prefer low water temperatures and high dissolved oxygen levels. The upper lethal temperature is 31 C and dissolved oxygen concentrations less than four parts per million are generally avoided (Bond 1963). Key Factors Influencing Status The very restricted distribution of this species suggests very specific habitat needs or preferences. Changes in habitat features and water quality would likely result in population declines. The effects of introduced predators and potential competitors, now prevalent in the Upper Klamath Basin, are not known. So little is known of the distribution, life history, and habitat needs of slender sculpins that assessing their status or understanding the precise effects of human activities is difficult. Margined Sculpin (Cottus marginatus) The margined sculpin is the only freshwater fish confined entirely to the middle Columbia River drainage in the northern portion of the Blue Mountains of eastern Washington and Oregon. Due to its limited range, the species is currently listed as a BLM tracking species, a State of Oregon vulnerable species; and a State of Washington monitor species. The historic distribution of margined sculpin has not been studied in detail, mainly because it overlaps the distribution of Paiute sculpin and is difficult to identify in the field. The most comprehensive study on die distribution of margined sculpins (Lonzarich 1993) revealed that they occur in the mainstem of the Tucannon and mainstem and tributaries of the Walla Walla (Washington) and Umatilla (Oregon) rivers (map 4.69). In the Walla Walla River Basin, they are found in the North and South forks, the Touchet River including the North, South and Wolf forks, and Pine, Dry, Mill, Couse, and Cottonwood creeks. In the Umatilla Basin, they are found in the McKay River and East Birch, Pearson, Johnson, Rail, and Buder creeks. Although confined to streams in the Blue Mountains, the species is abundant within this range. Habitat Relationships Lonzarich (1993) found that the margined sculpin prefers pools and glides with low velocity water flowing over cobble and gravel substrate. While it appears tolerant of variable habitat conditions, relatively little is known about this species. Most sculpin species prefer relatively low water temperatures. In Oregon, the margined sculpin is often found in association with rainbow trout, speckled dace, longnose dace, and Paiute sculpin (Wydoski and Whitney 1979). Key Factors Influencing Status The restricted distribution of the margined sculpin makes it especially vulnerable to environmental changes. Land management activities could lead to the rapid decline in margined sculpin population numbers and status. Major potential effects from these activities include reduced amounts of preferred pool habitat, habitat fragmentation, increased water temperatures, loss of streamside vegetation, increased water velocities, and increased sedimentation. Lonzarich (1993) noted the degraded condition from grazing and logging in the Touchet River, particularly the South and Wolf forks. Also, Oregon Department of Fish and Wildlife (1992) cited potential impacts from agricultural chemicals, heavy sedimentation, and toxic material spills as reasons for listing the species. Aquatics
Map 4.69-- Historical and current distribution of margined sculpin. A q u at ic s 1331
Wood River Sculpin (Cottus leiopomus) The Wood River sculpin is endemic to the Wood River drainage in south-central Idaho. The Wood River sculpin is currently listed as a State of Idaho species of special concern and as a sensitive species by the BLM and Region 4 of the Forest Service. The Wood River sculpin was first collected from the Little Wood River near Shoshone, Idaho in 1893 (map 4.70) (Gilbert and Evermann 1895). Historically, the range of Wood River sculpin consisted of all permanent, interconnected waters from the falls on the Malad River at Interstate 84 in Idaho upstream into the Little Wood and Big Wood rivers and their tributaries (Simpson and Wallace 1978). It is likely that the Wood River sculpin was the only sculpin present in the drainage. The Wood River sculpin was more widely distributed in the drainage historically than at present. 24 However, no basin-wide inventories have been conducted to determine its present range accurately. Inventories conducted on 26 streams in the drainage from the 1970s to 1990s found sculpins at 40 locations but not at 8 locations. 25 Where found, sculpin were common to abundant. Habitat Relationships The Wood River sculpin has similar habitat requirements as other sculpins found in Idaho (Merkley and Griffth 1993). The Wood River sculpin seems to select fast water riffles with boulder, cobble, and gravel substrate. In some streams, sculpins make limited use of overhanging banks and beaver ponds. In the Big Wood River, sculpins were found seasonally in ephemeral side channels with suitable cobble and boulder substrates. "Wallace, R.L. University of Idaho. 1995. Letter dated September to B. Reininger, Idaho Department of Fish and Game, Jerome, Idaho. "Personal communication. 1995. F. Partridge, Idaho Department of Fish and Game, Jerome, Idaho. Personal communication of unpublished data. Key Factors Influencing Status The most significant threat to Wood River sculpin is the loss of habitat caused by development of irrigation projects in the Wood River drainage and by floodplain encroachment. Habitat destruction from irrigation projects includes stream dewatering, flooding of stream channels by reservoir construction, and formation of migration barriers. Non-native fish introductions have also occurred. These introductions have created adverse effects on the population, including predation, competition, potential hybridization with Paiute sculpin, and potential introduction of disease. Most habitat loss occurred on private lands prior to the 1930s, with additional habitat loss resulting from overgrazing in the upper Big Wood River. More recently, sculpin habitat has been degraded by agriculture and residential development within the floodplain. Shoshone Sculpin (Cottus greenet) The Shoshone sculpin is endemic to springs along the Snake River in the Hagerman Valley of southcentral Idaho. Because of its restricted range and the development pressures on spring systems, the Shoshone sculpin is classified as threatened by the American Fisheries Society (Williams and others 1989), as a State of Idaho species of special concern, and as a sensitive species by the BLM. Shoshone sculpins are restricted to portions of the Snake River in south-central Idaho that contain spring systems (map 4.71). Wallace and Griffith (1982) reported the species from 49 locations within 25 spring systems in the Hagerman Valley. Most locations are along the north bank of the river in the Thousand Springs formation of Gooding County. Two localities along the south side of the river in Twin Falls County contained Shoshone sculpin. Shoshone sculpin also were collected from Billingsley Creek, a tributary of the Snake River near Hagerman. Many spring and stream systems in the region contain the more Aquatics
Map 4.70-- Historical and current distribution of Wood River sculpin. A quatics 1333
Map 4.71-- Historical and current distribution of Shoshone sculpin. 1334 Aquatics
common mottled sculpin (C. bairdi). Results of a recent Idaho Chapter American Fisheries Society Workshop (IDAFS 1995) indicate some population loss but an overall "fairly stable" population status during the past decade. Habitat Relationships Shoshone sculpin are found only in association with spring outflows. Highest population densities occur near the headwaters of springs and lower densities occur with decreasing influence of spring water on water quality (Wallace and Griffith 1982). Younger sculpins prefer areas with more plant cover and fewer large rocks than do older Shoshone sculpins. Both juvenile and adult Shoshone sculpins prefer relatively low water velocities (less than 20 cm per second) with temperatures near 15 C (Wallace and Griffith 1982). Key Factors Influencing Status Shoshone sculpins are dependent on maintenance of the natural integrity of spring flows. The numerous spring systems that are located along the Snake River provide a valuable, but finite resource. Diversion of spring water has caused dewatering of Shoshone sculpin habitat in many areas (Wallace and Griffith 1982). Spring waters are used for a variety of purposes, including aquaculture facilities, hydropower operations, and agriculture. These practices have diverted, dried, and polluted springs. Various private and Federal fish hatcheries also serve as sources of non-native invertebrates, fishes, diseases, and parasites. Malheur Sculpin (Cottus bairdi spp.) The Malheur sculpin is endemic to the Harney Basin of southeastern Oregon. This undescribed subspecies is listed as a sensitive species by the State of Oregon. The Malheur sculpin is endemic to streams in the Harney Basin, including the Silvies and Blitzen river systems (map 4.72). Historic distribution includes the Blitzen River and tributary streams on the Steens Mountain, the Silver Creek drainage, the Silvies River and tributary streams, and the isolated drainages of Poison and Rattlesnake creeks. The sculpin in the Harney Basin is considered by Bailey and Bond (1963) and Bond (1974) to represent an undescribed relative of the mottled sculpin in the Snake River drainage. Within the Silvies Basin, Bisson and Bond (1971) reported the Malheur sculpin from the mainstem Silvies River, Scotty Creek, and Emigrant Creek. According to the BLM (1992), Malheur sculpin occur on BLM-administered lands in the upper Silvies River and Emigrant, Yellowjacket, Hay, Myrtle, and Sawtooth creeks in the Silvies Basin. Historic collections suggest that the subspecies was broadly distributed within its range. Bond (1974) reported that the subspecies has been extirpated from the Rattlesnake Creek subbasin. Habitat Relationships Very little is known about the life history of the Malheur sculpin, but it is assumed to be comparable to that of other mottled sculpins, Cottus bairdi. According to Bond (1974), the Malheur sculpin requires cool-water streams with large gravel or rubble substrates for cover and spawning. It requires water temperatures below 26 C, with high dissolved oxygen and very low turbidity. Given these characteristics, the Malheur sculpin can occupy small headwater streams and larger rivers, such as the lower Blitzen River. Key Factors Influencing Status Malheur sculpin appear to be very sensitive to changes in water quality, including increases in temperature, sediments, and turbidity. Aquatic habitat and water quality conditions are considered poor in the upper Silvies River because of elevated water temperature, silt loads, and livestock grazing; and poor on Hay and Yellowjacket creeks because of elevated water temperature, silt loads, and timber harvesting (BLM 1992). On Emigrant Creek, BLM (1992) rated water quality condition as fair and aquatic habitat condition as good but considers both conditions to be declin- Aquatics
Map 4.72-- Historical and current distribution of Malheur sculpin. 1336 Aquatics
ing because of siltation, high water temperature, and upstream impacts from livestock grazing and logging. Biotic interactions are not specifically known, but the occurrence of the Malheur sculpin would appear to be negatively correlated with presence of introduced warm-water fishes such as catfish and centrarchids, which are more tolerant of turbid water conditions. Elevated water temperature, increased turbidity, and sediment transport caused by activities such as livestock grazing, road construction, and timber harvest activities are detrimental to the sculpin and have been cited by the BLM (1992) as causes for the decline of Malheur sculpin populations in the mainstem Silvies, Hay, Yellowjacket, and Emigrant creeks within the Silvies Basin. Conclusions Approximately 50 percent of the native fish taxa in the assessment area has exhibited significant declines compared with historic levels. Presently, 45 of the 88 native fish taxa (51%) in the assessment area are identified as threatened, endangered, sensitive, or of special concern by state or Federal agencies or by the American Fisheries Society. Eleven fish taxa are formally listed as threatened or endangered under the Endangered Species Act. The following important concepts have emerged from our review of historic and current distributions of rare fish and existing literature. 1. Many of these taxa are vulnerable to anthropogenic effects and stochastic events because of their restricted range and fragile habitat requirements. Four cyprinid fishes are restricted to one or two small spring systems: Borax Lake chub, Summer Basin tui chub, Hutton tui chub, and Foskett speckled dace. Several other species appear to be extremely rare, but their precise status is unclear. These species include the Klamath lamprey, Goose Lake lamprey, Lost River sucker, and shortnose sucker. The spring-dwelling fishes, such as the Borax Lake chub and Hutton tui chub, occupy unique desert habitats that are easily disturbed by off-road vehicles, livestock grazing, or other surface disturbances. Spring aquifers and associated substrates also may be degraded from over-withdrawal of groundwater, geothermal exploration, or other subsurface drilling. Many spring habitats of the Shoshone sculpin have been lost because of aquaculture facilities and small hydropower operations. Such species require protection of remaining habitat if the species are to persist. 2. Many of these taxa are subject to increased likelihood of extinction or extirpation as environmental variability combines with low population sizes. The native lake-dwelling suckers of the Klamath Basin (shortnose, Lost River, and Klamath largescale) have declined to the extent that hybridization among the species may be occurring within restricted, remaining spawning areas. Water quality in Upper Klamath and Agency lakes has severely reduced the distribution of native fishes and has caused fish mortality in the past. Drought exacerbates problems of water quality in the lakes. In the Warner Valley, the threatened Warner sucker was nearly eliminated during the drought of the early 1990s by a combination of the desiccation of lake habitats and the diversion dams that prevented access to lower sections of remaining tributaries. The species survived largely through temporary transfer of individuals to the Summer Basin. Drought caused similar problems to the Goose Lake lamprey when Goose Lake dried in the early 1990s. 3. Many of these taxa are poorly understood and in need of study and rigorous monitoring efforts. We know very little about the lampreys (with the possible exception of the Pacific lamprey), the northern roach, the leatherside chub, most of the tui chubs, the Foskett speckled dace, the Wood River bridgelip sucker, and the Malheur sculpin. Several of these taxa, for example the Hutton tui chub and the Foskett speckled dace, have long been recognized as distinct at the subspecific level yet lack formal scientific descriptions. Monitoring of habitat and populations is essential if management is to respond to factors that threaten the persistence of the narrowly distributed endemics. Aquatics