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<br />sucker, Xyrauchen texanus (Abbott); and mottled sculpin, Coitus
<br />bairdi Girard. In addition, a hybrid sucker, Catostomus latipinnis X
<br />Xyrauchen texanus, was collected.
<br />Twelve species of exotic fishes were taken: brown trout, Salmo trutta
<br />Linnaeus; rainbow trout, Salmo gairdneri Richardson; carp, Cyprinus
<br />carpio Linnaeus; Utah chub, Gila atraria (Girard); fathead minnow,
<br />Pimephales promelas Rafinesque; redside shiner, Richardsonius bal-
<br />teatus (Richardson); creek chub, SemotiZus atromaculatus (Mitchill);
<br />white sucker, Catostomus commersoni (Lacepede); channel catfish,
<br />/ctalurus punctatus (Rafinesque); black bullhead, /ctalurus melas
<br />(Rafinesque); green sunfish, Lepomis cyanellus Rafinesque; and wall-
<br />eye, Stizostedion vitreum vitreum (Mitchell). The occurrence and
<br />relative abundance of these indigenous and introduced fishes were
<br />described at each of the six major collecting areas.
<br />Little Hole (7 miles below dam) .- The only indigenous species oc-
<br />curring in the first 7 miles below the dam was the flannelmouth sucker;
<br />one adult specimen was captured and two more were observed (Table
<br />4). Rainbow trout were abundant, while fathead minnows and red-
<br />side shiners were collected in small numbers. The Colorado chub was
<br />reported in the tail waters of the dam in the summer of 1963, the first
<br />summer following impoundment (Rod Stone~ Utah Department of
<br />Fish and Game, personal interview), but was not taken here in the
<br />present study. No reproduction of any fishes was observed in this area.
<br />Bridgeport-Willow Creek (17-23 miles below dam).-The num-
<br />ber of species increased considerably at this location, but rainbow
<br />trout was still the dominant species. Indigenous species found here
<br />were flannelmouth sucker, bluehead sucker, and speckled dace. One
<br />Colorado chub and one humpback chub (tentative identification) were
<br />collected here in 1963. In addition to the fathead minnow and redside
<br />shiner, exotic fishes taken were brown trout (recently stocked by the
<br />Utah State Department of Fish and Game), Utah chub, creek chub,
<br />and black bullhead. Reproductive success of indigenous fishes was ob-
<br />served here only in 1965 for flannelmouth sucker, bluehead sucker,
<br />and speckled dace (Table 5), Exotic species reproducing here in 1965
<br />were fathead minnows and redside shiners. Fathead minnow repro-
<br />duction was also observed in 1966, but young were found only in a
<br />warm, shallow, side-channel that was cut off from the main river.
<br />Lodore (46 miles below dam) ,-The abundance of Colorado chub,
<br />flannelmouth sucker, bluehead sucker, and speckled dace at this sta-
<br />tion increased from that observed upstream (Table 4), Exotic species
<br />commonly found here were rainbow trout, carp, redside shiner, fat-
<br />head minnow, and channel catfish. The hybrid sucker was collected
<br />
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