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Introduction <br />Razorback sucker, Xyrauchen texanus (RBS), is a unique catostomid exhibiting extreme <br />morphological adaptation to the Colorado River. RBS are at risk of extinction throughout their <br />range, primarily due to the transition of the Colorado River from a rigorous lotic environment to a <br />series of large manmade impoundments (Minckley 1995; Starnes 1995). This habitat <br />transformation, coupled with the introduction of exotic fish, has severely impacted the most unique <br />assemblage of fish species in North America. Small populations of RBS are currently found in the <br />Green River, upper Colorado River, and San Juan River subbasins; lower Colorado River; Lakes <br />Havasu, Mead and Mohave; and in small tributaries of the Gila River subbasin (Verde River, Salt <br />River, and Fossil Creek). Extant populations of RBS are small with little or no recruitment. <br />Threats to RBS include loss of spawning and rearing habitat resulting from water development <br />projects, stream flow regulation, competition with, and predation by, nonnative fish species, and <br />pesticides and pollutants (U.S. Fish & Wildlife Service 2002). <br />The RBS was listed as endangered in 1991 under the Endangered Species Act of 1973 (U. S. <br />Fish and Wildlife Service 1998). A recovery plan for RBS was completed in 1998 and recovery <br />goals finalized in 2002. The short-term recovery goal, as identified by both documents, is to <br />prevent extinction of the species. The long-term goals are to recover the species and facilitate <br />down-listing and eventual delisting. Captive propagation has been identified as a vital component <br />for accomplishing short and long term goals. The development of hatchery broodstocks to produce <br />genetically appropriate fish for recovery efforts is essential to establish new and augment existing <br />populations. <br />This Genetic Management and Captive Propagation Plan (plan) provides clear guidelines for <br />developing and maintaining RBS broodstocks at Dexter National Fish Hatchery and Technology <br />Center (Dexter NFHTC). The purpose of this document is twofold: to provide the framework for <br />maintaining genetic reserve populations of RBS that serve as broodfish, and to provide a captive <br />propagation strategy that ensures production fish adequately represent the available RBS genome.