FWS declines listing of Bonneville Cutthroat Trout, finding 80 percent of occupied habitat to be in fair to excellent condition
73 Fed. Reg. 52235, 73 FR 52235, Vol. 73, No. 175 (Tuesday, September 9, 2008)(DEPARTMENT OF THE INTERIOR; Fish and Wildlife Service; 50 CFR Part 17; WS-R6-ES-2008-0023; 1111 FY07 MO-B2 Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Bonneville Cutthroat Trout as Threatened or Endangered)
According to the National Park Service, the Bonneville cutthroat trout is the only trout native to Great Basin National Park and East Central Nevada, and the species was abundant in Lake Bonneville 16,000 to 18,000 years ago. As the climate changed and the lake level dropped, the trout migrated into the higher mountain streams where they eventually became trapped. The U.S. Fish and Wildlife Service agrees that populations of Bonneville Cutthroat Trout have been greatly reduced over the last 200 years, with much loss occurring in the late 19th and early 20th century. However, FWS concludes that recent surveys have shown that the numbers of BCT populations have increased in the last 3 decades and the subspecies remains widely distributed throughout a large geographic area. FWS found no evidence of continuing declines in the overall distribution or abundance of BCT during the last several decades. A substantial increase in the number of known populations has been documented and habitat quality is good to excellent in over half (52 percent) of BCT habitat, and fair to excellent in 80 percent of BCT habitat.
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce our 12-month finding on a petition to list the Bonneville cutthroat trout (Oncorhynchus clarkii utah) as a threatened subspecies throughout its range in the United States, pursuant to the Endangered Species Act of 1973, as amended (Act). After a thorough review of all available scientific and commercial information, we find that listing the Bonneville cutthroat trout as either threatened or endangered is not warranted at this time. We ask the public to continue to submit to us any new information that becomes available concerning the status of or threats to the subspecies. This information will help us to monitor and encourage the conservation of the subspecies.
EXCERPT FROM FWS FINDING: Hybridization, mostly with nonnative rainbow trout and nonnative subspecies of cutthroat trout that have established self-sustaining populations in many areas in the range of BCT, has historically been an issue of management concern. However, current State management has greatly reduced opportunities for further genetic introgression. States continue to monitor introgression in BCT throughout its range. We find that the limited presence of genetic material from other fish species or subspecies (typically less than 10 percent) is not a threat to BCT conservation populations. Populations or individual fish with a low level of introgression are morphologically, ecologically, and behaviorally indistinguishable from nonintrogressed (i.e., pure) BCT. Slightly introgressed BCT populations, with low amounts of genetic introgression detectable only by molecular genetic methods (i.e., conservation populations), are an important component of BCT conservation. Genetically pure populations (71 core populations) are distributed throughout the current range of BCT. State and Federal agencies are implementing strategies and actions to protect BCT populations from invasion of nonnative species or subspecies that may interbreed with BCT. Brook trout, brown trout, and rainbow trout compete with BCT where they are sympatric. Managers are monitoring competition from nonnative fish in BCT waters, and implementing ongoing management strategies and actions to curtail it. However, 1,365 km (848 mi) of habitat occupied by BCT conservation populations are free of nonnative trout. The BCT persists as a widely distributed subspecies; 153 conservation populations exist throughout the historic range, and a metapopulation structure exists in each GMU. Nonintrogressed BCT core populations exist in habitats secure from nonnative trout and thus are protected from potential hybridization throughout the subspecies’ historic range. Although distribution of BCT has been reduced from historic levels (the subspecies now occupies about 35 percent of historic habitat), the 2005 rangewide status report on BCT documented the continued existence of conservation populations throughout its current range, and that 80 percent of occupied habitat is in fair to excellent condition. We have thoroughly assessed the current status of BCT, the mitigation of existing threats, and the existence of laws and regulations that minimize adverse effects of land management and other activities on BCT. We find that the magnitude and imminence of threats do not indicate that the subspecies is in danger of extinction, or likely to become endangered, throughout all or any significant portion of its range, within the foreseeable future. Therefore, we find that listing the BCT as a threatened or an endangered species under the Act is not warranted at this time.