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<br /> <br /> <br />1 <br /> <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br /> <br /> <br />300mm standard length) captured in 1987 indicated 27 G. cypha and 216 G. <br />robusta (Douglas et al. 1987). This suggests that morphological variation <br />apparent in some locations in which Gila intergrades occur (reviewed by Valdez <br />and Clemmer, 1982) may be inherent, or induced by recent habitat changes, The <br />Yampa River humpback chub populations are more abundant than previously <br />thought and the separation between syntopic G. cypha and G. robusta in that <br />system mandates further study and protection. <br />Adult humpback chub were most often collected in eddy habitat (average <br />depth about 5 feet) although there was some use of shoreline runs and riffles. <br />These fish were caught in association with roundtail chub and c~iaznel catfish <br />(FWS unpu'ulished data). <br />Spawning: In 1986, FWS documented spawning of humpback chub in Yampa Canyon <br />with the capture of 2 ripe or spent females and 2 ripe males. This was <br />confirmed in 1987 with the capture of an additional ripe female, 8 ripe males <br />and 11 tuberculated fish (sex not determined). Thus, a total of 24 humpback <br />chub were captured in breeding condition in the Yampa River in 1986 and 1937. <br />Ripe fish were collected in eddy and shoreline run habitat during and <br />immediately following pear, spring flows (July 5 to July 15, 1986: RM 18-18.1, <br />and May 18 to June 29, 1987: RM 13-37.1). Humpback chub spawning has also <br />been observed during spring runoff in the Colorado River (Archer et al. 1985, <br />Valdez and Clemmer 1982). <br />Juvenile: Larval and postlarval humpback chub have been tentatively identified <br />in Yampa and Cross Mountain Canyon (RM 0-56) collections by the Larval Fish <br />27 <br />