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The reduction in numbers and biomass of Trout in The lower reaches is primarily • the result of reductions in cover and water velocity, increased Temperature fluctuations and high summer temperature and changing water chemistry (suspended solids). The most abundant species of fish in Trout Creek in the vicinity of Edno Mine is the mottled sculpin, Coitus bairdi (Table 2.7-18). Trout Creek in The vicinity of the Edna Mine and upstream provides this species with excellent habitat. This species reaches its greatest abundance in riffle areas of rocky-bottomed, clear, cool, fast-flowing mountain streams. Mottled sculpins feed primarily on a variety of aquatic invertebrates, with the Trichoptera and Diptera being most important. Sculpins ore an important forage fish for larger trout and ore consumed regularly (Brown 1971, Beckman 1974). The mottled sculpin is commonly associated with the speckled dace (Baxter and Simon 1970). Table 2.7-IB shows that the speckled dace is on abundant species in the vicinity of the Edna Mine. The food habits of this species is similar to the sculpin, olihough it is more omnivorous and consumes plant material as well (Carlander 1969). Five species of fish were collected from Oak Creek (Table 2.7-20). Each species was present at both stations, although densities varied considerably between • stations. Of the species listed, all are permanent residents and none are threatened or endangered, and no threatened or endangered species are expected to occur in Oak Creek. The estimated density and biomass of each species is presented by station in Table 2.7-21. The only salmonid (trout) present in Oak Creek in the vicinity of the Edna Mine is the Rainbow trout. This species is only important at Station I, and its population is sustained by periodic stocking. Oak Creek in the vicinity of Station I is usually stocked three times each summer with catchable sized Rainbow by The Colorado Division of Wildlife. Although Rainbows were common at Station I (Table 2.7-21), there was a conspicuous absence of fingerling and small trout indicating a low spawning success rate. Fish numbers and biomass are considerably higher at Station 2 than Station I. This is primarily due to changes in the trout and Mountain sucker (Catostomidoe) population (Table 2.7-22), reflecting the effects of channelization in the vicinity of Station I and other habitat factors. Station 2 provides better sucker habitat, with a flatter gradient (lower water velocity) amd much more cover with deeper and more frequent pools (Table 2.7-10). The Mottled sculpin is the second most dominant fish • at the Oak Creek stations. As in Trout Creek, this stream provides good habitat for 2.7-60