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71
<br />not result in natural recruitment. Populations established with successive year-
<br />class representatives by reintroduction will still lack the capability to perpetuate
<br />themselves. We will eventually need the culture techniques and the broodstock
<br />currently being developed at Dexter National Fish Hatchery, but right now, if we
<br />are ever to regain natural recruitment, egg and larval requirements are crucial.
<br />Equally important, an electrophoretic comparison of Yampa River, Lake Mohave and
<br />Senator Wash Reservoir stock should be evaluated before a broodstock is selected for
<br />the hatchery program because of the hybridization suggested.
<br />Memorandums of Understanding (M.O.U.'s), involving interstate waters, which infer
<br />that adequate protection is provided by the current reintroduction program jeopardize
<br />the capability to maintain or upgrade habitat quality for this species through the
<br />Fish and Wildlife Coordination Act, NEPA or other related legislation.
<br />Considering the apparent need for relatively warm egg incubation temperatures, some-
<br />where along the lower Colorado River will be the most feasible location to attempt
<br />recovery on the mainstream. The lack of spawning substrate may be solved through
<br />modification of proposed projects, but only if we define ',and build-in the early
<br />development requisites, will these projects result in the , maintenance of a razorback
<br />sucker population.
<br />LITERATURE CITED
<br />Behnke, R. J. and D. E. Benson. 1980. Endangered and Threatened Fishes of the Upper
<br />Colorado River Basin. U.S. Fish and Wildlife Service Cooperative Extension
<br />Service, Colorado State University, Ft. Collins Co.,',Bulletin 503A, 34 p.
<br />Bulkey, R. V., R. Pimentel and C. R. Berry, Jr. 1981. Habitat Preference Studies
<br />of Colorado River Endangered Fishes. In "Symposium on the Aquatic Resource
<br />Management of the Colorado River Ecosystem", November 1981, Las Vegas, Nevada,
<br />Utah State University, In press.
<br />Ellis, M. M. 1914. Fishes of Colorado. University of Colorado Studies, No. XI,
<br />No. 1; 12-128.
<br />Gustafson, E. S. 1975. Early Development, Adult Sexual Dimorphism, and Fecundity
<br />of the Razorback Sucker, Xyrauehen texanus (Abbott).', Final Report to U.S. Fish
<br />and Wildlife Service, Contract No. 14-16-0002-3585,'Arizona State University,
<br />Tempe, Arizona. 43p.
<br />Holden, P. B. 1973. Distribution, Abundance and Life History of the Fishes of the
<br />Upper Colorado River Basin. pH D Dissertation, UtahlState University, Logan,
<br />Utah. 59 p.
<br />Holden, P. B. and C. B. Stalnaker. 1975, Distribution and Abundance of Mainstream
<br />Fishes of the Middle and Upper Colorado River Basins, 1967-1973. Transactions
<br />of the American Fisheries Society 104(2):217-231.
<br />Hubbs C. L. and R. R. Miller. 1953. Hybridization in Nature Between the Fish
<br />Genera Catostomus and Xyrauehen. Michigan Academy of Science, Arts, and
<br />Letters No. 38:207-233, PLATES I-IV.
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