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Endangered and Threatened Wildlife and Plants: 12-Month Finding for an Amended Petition To List the Westslope Cutthroat Trout as Threatened Throughout Its Range

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Fish and Wildlife Service, Interior.


Notice of 12-month petition finding.


We, the Fish and Wildlife Service, announce a 12-month finding for an amended petition to list the westslope cutthroat trout (Oncorhynchus clarki lewisi) as threatened throughout its range pursuant to the Endangered Species Act of 1973, as amended. After review of all available scientific and commercial information, we find that listing the westslope cutthroat trout is not warranted at this time.


The finding announced in this document was made on April 5, 2000.


Data, information, comments, or questions regarding this notice should be sent to the Chief, Branch of Native Fishes Management, U.S. Fish and Wildlife Service, Montana Fish and Wildlife Management Assistance Office, 4052 Bridger Canyon Road, Bozeman, Montana 59715. The complete administrative file for this finding is available for inspection during normal business hours, by appointment, at the above address. The status review document for westslope cutthroat trout (U.S. Fish and Wildlife Service 1999) may also be obtained at that address, or at our Internet web site at <​cutthroat>.

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Lynn R. Kaeding, at the above address, telephone (406) 582-0717, or e-mail

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Section 4(b)(3)(B) of the Endangered Species Act of 1973 (Act), as amended (16 U.S.C. 1531 et seq.), requires that within 90 days of receipt, to the maximum extent practicable, we make a finding on whether a petition to list, delist, or reclassify a species presents substantial scientific or commercial information indicating that the requested action may be warranted. If the petition contains substantial information, the Act requires that we initiate a status review of the species and publish a 12-month finding indicating whether the petitioned action is (a) not warranted, (b) warranted, or (c) warranted but precluded from immediate listing proposal by other pending proposals of higher priority. Such 12-month findings are to be published promptly in the Federal Register.

On June 6, 1997, we received a formal petition to list the westslope cutthroat trout (Oncorhynchus clarki lewisi) as threatened throughout its range and designate critical habitat for this subspecies pursuant to the Act. The petitioners are American Wildlands, Clearwater Biodiversity Project, Idaho Watersheds Project, Inc., Montana Environmental Information Center, the Pacific Rivers Council, Trout Unlimited's Madison-Gallatin Chapter, and Mr. Bud Lilly.

The westslope cutthroat trout (WCT) is 1 of 14 subspecies of cutthroat trout native to interior regions of western North America (Behnke 1992). Cutthroat trouts owe their common name to the distinctive red slash that occurs just below both sides of the lower jaw. Adult WCT, especially males during the spawning season, typically exhibit bright yellow, orange, and red colors. Characteristics of WCT that distinguish this fish from the other cutthroat subspecies include a pattern of irregularly shaped spots on the body that has few spots below the lateral line, except near the tail; a unique number of chromosomes; and other genetic and morphological traits that appear to reflect a distinct, evolutionary lineage (Behnke 1992).

The historic range of WCT is considered the most geographically widespread among the 14 subspecies of inland cutthroat trout (Behnke 1992). Although not known precisely, the historic distribution of WCT in streams and lakes can be summarized as follows: West of the Continental Divide, the subspecies is native to several major drainages of the Columbia River basin, including the upper Kootenai River drainage from its headwaters in British Columbia, through northwest Montana, and into northern Idaho; the Clark Fork River drainage of Montana and Idaho downstream to the falls on the Pend Oreille River near the Washington-British Columbia border; the Spokane River above Spokane Falls and into Idaho's Coeur d'Alene and St. Joe River drainages; and the Salmon and Clearwater River drainages of Idaho's Snake River basin. The historic distribution of WCT also includes disjunct areas draining the east slope of the Cascade Mountains in Washington (Methow River and Lake Chelan drainages), the John Day River drainage in northeastern Oregon, and the headwaters of the Kootenai River and several other small disjunct regions in British Columbia. East of the Continental Divide, the historic distribution of WCT includes the headwaters of the South Saskatchewan River drainage (United States and Canada); the entire Missouri River drainage upstream from Fort Benton, Montana, and extending into northwest Wyoming; and the headwaters of the Judith, Milk, and Marias Rivers, which join the Missouri River downstream from Fort Benton. Today, various WCT stocks remain in each of these major river basins in Montana, Idaho, Washington, Oregon, and Wyoming, but occur in scattered, disjunct populations in Canada.

On July 2, 1997, we notified the petitioners that our Final Listing Priority Guidance, published in the December 5, 1996, Federal Register (61 FR 64425), designated the processing of new listing petitions as being of lower priority than completion of emergency listings and processing of pending Start Printed Page 20121proposed listings. A backlog of listing actions, as well as personnel and budget restrictions in Region 6 (Mountain-Prairie Region), which was assigned responsibility for the WCT petition, prevented our staff from working on a 90-day finding for the petition.

On January 25, 1998, the petitioners provided an amended petition to list the WCT as threatened throughout its range and designate critical habitat for the subspecies. The amended petition contained additional new information in support of the requested action. Because substantial new information was provided, we treated the amended petition as a new petition.

On June 10, 1998, we published a notice in the Federal Register (63 FR 31691) of a 90-day finding that the amended WCT petition provided substantial information indicating that the requested action may be warranted and immediately began a comprehensive status review of WCT (U.S. Fish and Wildlife Service 1999). In the notice, we asked for data, information, technical critiques, comments, or questions relevant to the amended petition. The comment period closed August 10, 1998; however, we reopened the comment period on August 17, 1998 (63 FR 43902), until October 13, 1998.

Petitioners' Assertions

The petitioners assert that remaining, genetically pure stocks of WCT occur almost exclusively in small, isolated streams in mountainous areas. In Montana, the region for which most data were provided, the petitioners indicate that stocks of genetically pure WCT occur in about 3.5 percent and 1.5 percent of their historic stream habitat in the Kootenai River and upper Missouri River drainages, respectively. The petition includes similar percentages for genetically pure WCT stocks in other drainages in Montana.

The petitioners assert that it is common for today's WCT stocks to have some degree of hybridization with introduced, nonnative trout. The petitioners further assert that stocks of WCT now occur in 11 percent of historic habitat in Idaho and 41 percent in Oregon, although data on genetic purity are not available for most of those stocks. The petitioners have little information on the status of native WCT stocks in Alberta, British Columbia, and Washington, although several stocks have been confirmed by recent studies. According to the petitioners, only about half of the few streams in Wyoming that were historic habitat for WCT now have stocks of this subspecies, but all of these stocks are considered hybridized to some degree with introduced, nonnative trout.

The petitioners assert that the WCT should be listed as threatened because the subspecies' present distribution and abundance are substantially reduced from historic conditions; remaining stocks are small and widely separated and continue to decline in abundance; and the threats to the survival of WCT are pervasive and ongoing. The petitioners allege that threats to WCT include habitat destruction from logging and associated road building; adverse effects on habitat resulting from livestock grazing, mining, urban development, agricultural practices, and the operation of dams; historic and ongoing stocking of nonnative fish species that compete with or prey upon WCT or jeopardize the subspecies' genetic integrity through hybridization; and excessive harvest by anglers.

The petitioners further assert that programs to protect and restore WCT are inadequate or nonexistent, and that stocks of this fish continue to be threatened by a wide variety of ongoing and proposed activities.

Status Review

A review team consisting of U.S. Fish and Wildlife Service biologists from Region 1 (headquartered in Portland, Oregon) and Region 6 (headquartered in Denver, Colorado) conducted the WCT status review. Team members were: Scott A. Deeds, Fish and Wildlife Biologist, Upper Columbia River Basin Field Office, Spokane, Washington; Lynn R. Kaeding, Team Leader and Chief, Branch of Native Fishes Management, Montana Fish and Wildlife Management Assistance Office, Bozeman, Montana; Dr. Samuel C. Lohr, Fishery Biologist, Snake River Basin Office, Boise, Idaho; and Douglas A. Young, Fish and Wildlife Biologist, Central Oregon Field Office, Bend, Oregon.

In response to our June 10 and August 17, 1998, Federal Register notices, we received 56 comments from State game and fish departments, the U.S. Forest Service, National Park Service, Tribal governments, and private corporations, as well as private citizens, organizations, and other entities containing information on WCT (U.S. Fish and Wildlife Service 1999). State game and fish departments provided information on the status, distribution, abundance, and genetics of the WCT in their respective States. We also reviewed information on WCT obtained from scientific journal articles, agency reports and file documents, and telephone interviews and written correspondence with natural resources managers familiar with WCT. In addition, we analyzed the extensive information on WCT provided by the Interior Columbia River Basin Ecosystem Management Project (1996). Detailed procedures and results of our comprehensive assessment of the available information are described in the WCT status review document (U.S. Fish and Wildlife Service 1999) and summarized in this notice.

Throughout the historic range of WCT, few of the remaining WCT stocks have been genetically classified on the basis of chromosome counts, biochemical characteristics, or molecular genetic information. Although application of such genetic techniques for characterizing fish stocks is becoming more common today, in most cases the taxonomic classification of extant WCT stocks has been based largely on the spotting patterns shown by the fish and the professional judgments and experiences of the fishery biologists who examined the fish in the field. Although WCT stocks with varying degrees of genetic purity are known to occur across the subspecies' range, there is currently little definitive information on the genetic characteristics of most WCT stocks (U.S. Fish and Wildlife Service 1999). Even in Montana, where an extensive database on the genetic characteristics of many WCT stocks exists, the precise genetic characteristics of most stocks are unknown. Consequently, we based the WCT status review on the professional judgments made by the State game and fish departments that the fish the departments classified as WCT actually represented the subspecies, even though the precise genetic characteristics of those stocks may not be known, or the stocks may consist of intercross progeny that were the product of some low or nondetectable level of interbreeding between WCT and another fish species. In addition, given the very small, disjunct populations in Canada, we evaluated WCT status on the basis of WCT stocks that currently occur within the historic range of the subspecies in the United States (i.e., introduced and naturally occurring stocks in Canada and introduced stocks outside the historic range in the United States were not included in the evaluation).

Status Review Findings

The National Marine Fisheries Service and our agency have adopted criteria (61 FR 4722) for designation of Distinct Population Segments (DPSs) for vertebrate organisms, such as WCT, under the Act. To constitute a DPS, a stock or group of stocks must be: (1) Discrete (i.e., spatially, ecologically, or Start Printed Page 20122behaviorally separated from other stocks of the taxon); (2) significant (e.g., ecologically unique for the taxon, extirpation would produce a significant gap in the taxon's range, the only surviving native stock of the taxon, or substantial genetic divergence occurs between the stock and other stocks of the taxon); and (3) the population segment's conservation status must meet the Act's standards for listing. We found no morphological, physiological, or ecological data for WCT that indicated unique adaptations of individual WCT stocks or assemblages of stocks anywhere within the historic range of the subspecies. Although the disjunct WCT stocks in Canada, Washington, and Oregon, for example, met the first criterion for DPS designation (discreteness), evidence in support of the second criterion (significance) appeared entirely speculative for those and other stocks across the range of the subspecies. Congress has made clear (61 FR 4722) that in the absence of compelling evidence of genetic, ecological, or other characteristics that indicate a unique significance of a stock or assemblage of stocks, DPSs should be used “sparingly” in the context of the Act. We found no compelling evidence in support of recognizing DPSs for WCT. Instead, a single WCT population was recognized for purposes of the status review (U.S. Fish and Wildlife Service 1999).

Information provided primarily by State game and fish departments in Montana, Idaho, Washington, and Oregon indicated WCT currently occur in about 4,275 tributaries or stream reaches that collectively encompass more than 23,000 linear miles (36,800 kilometers (km)) of stream habitat (U.S. Fish and Wildlife Service 1999). Those WCT stocks are distributed among 12 major drainages and 62 component watersheds in the Columbia, Missouri, and Saskatchewan River basins. In addition, WCT are known to occur naturally in 6 lakes in Idaho and Washington, totaling about 72,900 hectares (ha) (180,000 acres (ac)), and in at least 20 lakes in Glacier National Park, Montana, totaling 2,165 ha (5,347 ac). The distribution of WCT in any particular stream or stream reach was based on field sampling or the professional judgment of fisheries biologists familiar with that geographic region. Because sampling all stream reaches in a watershed is generally not feasible, especially in remote and mountainous regions, information concerning linear stream distances occupied by WCT that the departments supplied were often total lengths for an entire stream in which WCT were known or suspected to occupy some portion. Although WCT stocks that occupied large, mainstem rivers and lakes and their principal tributaries are reduced from their historic levels, the degree that those stocks are reduced cannot be determined precisely because definitive historic data are limited. Nonetheless, we find that viable, self-sustaining WCT stocks remain widely distributed throughout the historic range of the subspecies, most notably in headwater areas.

In the context of the Act, the term “threatened species” means any species (or subspecies or, for vertebrates, DPS) that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The term “endangered species” means any species that is in danger of extinction throughout all or a significant portion of its range. The Act does not indicate threshold levels of historic population size at which (as the population of a species declines) listing as either “threatened” or “endangered” becomes warranted. Instead, the principal considerations in the determination of whether or not a species warrants listing as a threatened or endangered species under the Act are the threats that currently confront the species and the likelihood that the species will persist in “the foreseeable future.”

Evidence from the Missouri River basin indicates that a conspicuous decline in the WCT population occurred early in the twentieth century (U.S. Fish and Wildlife Service 1999). That decline was mainly attributed to rapid, abundant colonization of mainstem rivers and their major tributaries by one or more introduced, nonnative fish species (e.g., brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Oncorhynchus mykiss)) that had adverse effects on WCT. Our analysis also showed that the rate of decline in the WCT population is markedly lower today than it was early in the twentieth century. The evidence from the Missouri River basin provided a model for the historic decline of WCT that is probably applicable to WCT in other regions of the subspecies' range.

We also have evidence that many of the headwater streams inhabited by extant WCT stocks throughout the subspecies' range are relatively secure from colonization by the nonnative fishes that are known to adversely affect WCT. Throughout the inland, western United States today, stocks of various subspecies of indigenous cutthroat trout often persist in high-elevation, high-velocity, headwater streams, where they appear to have a competitive advantage over nonnative fishes. Thus, the headwater streams inhabited by many extant WCT stocks may be relatively secure from colonization by nonnative fishes. In addition, because they occur in high-elevation areas, those headwater streams are relatively secure from the adverse effects of human activities.

Spatial separation of many extant WCT stocks precludes natural movement and interbreeding among some stocks, thereby potentially increasing the likelihood that those stocks will become extinct due to limited genetic variability. In addition, the probable small sizes of some WCT stocks and the short stream reaches that they might inhabit make those stocks more vulnerable to extirpation due to natural catastrophes such as floods, landslides, wild fires, and other stochastic environmental events. Remaining WCT stocks in the Lower Missouri River and part of the Columbia River (in Washington) drainages, for example, occupy stream reaches that average 2.9 and 3.4 miles (4.6 and 5.4 km) long, respectively (U.S. Fish and Wildlife Service 1999). Despite the probable small sizes of many extant WCT stocks that inhabit restricted, headwater stream reaches, however, we find no evidence of negative impacts of inbreeding within stocks. Similarly, although the probable small sizes of some of those WCT stocks and the short stream reaches that they inhabit make some stocks more vulnerable to extirpation due to stochastic environmental events, we find no evidence that the loss of WCT stocks that could result from such infrequent, natural catastrophes would threaten the continued existence of the subspecies as a whole (U.S. Fish and Wildlife Service 1999).

The status review revealed that most of the habitat for extant WCT stocks lies on lands administered by Federal agencies, particularly the U.S. Forest Service (U.S. Fish and Wildlife Service 1999). Moreover, most of the strongholds for WCT stocks occur within roadless or wilderness areas or national parks, all of which afford considerable protection to WCT. In addition, numerous existing Federal and State regulatory mechanisms, if properly administered and implemented, are working to protect WCT and their habitats throughout the range of the subspecies. For example, the States generally restrict the harvest of WCT, and in many regions only catch-and-release angling is allowed. However, some regions have regulatory mechanisms with primary goals that Start Printed Page 20123could maintain habitat conditions at levels that are less than optimal for WCT.

We also are encouraged by ongoing State and local programs, most notably those in Montana, to protect and restore WCT within its historic range (U.S. Fish and Wildlife Service 1999). The U.S. Forest Service, State game and fish departments, and National Park Service reported more than 700 ongoing projects directed toward the protection and restoration of WCT and their habitats. In addition, on private lands in Montana's Columbia River basin, for example, Plum Creek Timber Company is working closely with us to develop a Native Fish Habitat Conservation Plan that includes provisions for the conservation of WCT on 1.5 million acres of Plum Creek property. Elsewhere in Montana, restoration activities under way as part of the Blackfoot Challenge, a cooperative endeavor between private landowners and public agencies to conserve and restore streams and riparian habitats in the Blackfoot River valley, include removal of fish-passage barriers, screening of irrigation diversions to prevent the loss of WCT to canals, and general improvement of instream fish habitat.

Finally, WCT also accrue some additional level of protection from the Act's section 7 consultation process in the numerous geographic areas where WCT distribution and habitat requirements overlap with the distributions of one or more fish species currently listed as threatened or endangered under the Act, specifically, bull trout (Salvelinus confluentus), steelhead (Oncorhynchus mykiss), and Pacific salmon species and their habitats on Federal lands in the Columbia River basin. Conservation efforts to protect these species, improve available habitat, and minimize adverse impacts on them would provide similar conservation benefits to WCT.

The Act identifies five factors of potential threats to a species: (1) The present or threatened destruction, modification, or curtailment of the species' habitat or range; (2) overutilization for commercial, recreational, scientific, or educational purposes; (3) disease or predation; (4) the inadequacy of existing regulatory mechanisms; and (5) other natural or manmade factors affecting the species' continued existence. The overall WCT population has been reduced from historic levels, and extant stocks of this subspecies face threats from some of these factors in several areas of the historic range. However, we find that the magnitude and imminence of those threats are small. WCT have a widespread distribution, and there are numerous robust populations throughout its range.

On the basis of the best available information, which is detailed and analyzed in the status review document (U.S. Fish and Wildlife Service 1999) and summarized in this notice, we conclude that the WCT is not likely to become a threatened or endangered species within the foreseeable future. Therefore, listing of the WCT as a threatened or endangered species under the Act is not warranted at this time.

References Cited

Behnke, R.J. 1992. Native trout of western North America. American Fisheries Society Monograph 6.

Interior Columbia River Basin Ecosystem Management Project. 1996. Key salmonid current-status database (CRBFISH6). Available at ICBEMP web site <>.

U.S. Fish and Wildlife Service. 1999. Status review for westslope cutthroat trout in the United States. Regions 1 and 6. Available at our web site <<​cutthroat>.

Authors: The primary author of this document is Lynn R. Kaeding (see ADDRESSES section).


The authority for this action is the Endangered Species Act (16 U.S.C. 1531 et seq.).

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Dated: April 5, 2000.

Jamie Rappaport Clark,

Director, Fish and Wildlife Service.

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[FR Doc. 00-9259 Filed 4-13-00; 8:45 am]