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- f <br />We suspect that cooler <br />pawning and seasonal temperature change. <br />temperatures in May and June in the upper Green River has adversely <br />"y -15 Years. This <br />over the past 10 <br />?'impacted the chub in the Dinosaur area <br />temperature caused impact, we believe, has reduced numbers to only a <br />backs <br />present sporatic occurrence where before 1970 one could take htmnP <br />in greater numbers from the Dinosaur National Monument area of the Green <br />River. <br />Data on chemical tolerances and lethal bioassay tests are still <br />incomplete. Diseases and parasites associated with wild humpback <br />chub probably do not significantly impact the species unless a stress- <br />ful situation exists. The humpback chub in the Little Colorado <br />River area do have a high incidence of Lernaea but this does not <br />seem to impact them. <br />Bonytail Chub <br />We do not have enough information on this species to discuss <br />needed habitat. The present distribution is quite low and the species <br />fish in <br />found a few bonytail type <br />is on the edge of extinction. We only <br />the Green River in the Grays-Desolation canyon area and none in the <br />Colorado River. We do have some taxonomic problems with this species <br />and hope to have this resolved by the final report date. <br />Razorback Sucker <br />This species is decreasing quite drastically in the upper Colorado <br />d signi- <br />River. Over the past 5 to 10 years numbers seem to have droppe <br />a decline in this species 7 <br />ficantly. We believe we are observing <br />53