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probably exist in the wild (Holden and Stalnaker 1Ji0, Smith et al. <br />,_ <br />1979, Rosenfeld 1Jf36a). ;+Iost "intermediate" specimens i'rom Iil~tck <br />Rocks and other Upper Basin locales may represenc varia~ivn uT~o~,~, <br />~~~ ~~~ humpback chub (Rosenfeld 1J£i6a) . <br />Recreational angling at Black Rocks could affect humpback <br />chubs if fishing pressure were to increase from its present low <br />level and if angler awareness -of endangered species remains low. <br />Angling is an effective sampling method for humpback chubs (Wick et <br />al. 1981, Archer et al. 1985); About 6000 people per year use the <br />river reach thzt includes Black Rocks; perhaps 10~ of .these angle <br />somewhere on this reach (C. Sovage, BLM; pers. comm.). <br />:Nonnative fish species are implicated in decline of Colorado <br />'River native fishes (Miller 1961, Minckley and Deacon 1968, Holden <br />and Stalnaker 1975b), but cause--and-effect relationships involving <br />competition and predation are unclear. Channel catfish may prey <br />upon humpback chubs (Behnke and Benson 1983). Adult chubs have <br />exhibited apparent catfish bite marks (I{aeding and Zimmerman 1983). <br />,,- <br />CONCLUSIONS AND RECOMhgF,hDATIONS <br />Literature review indicates that specific habitat needs of <br />}tumpbttck chub are largely unknown. Fopulatinris of the species arc <br />few, and these are vulnerable because they rely on a feta unique <br />hnbitrrt.s. Re~;nrdless of a lack ~,f information about ft~~.tors <br />affecting species survival, Federal recovery goals for humpback c_•hub <br />ll <br />