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<br />002J39 <br /> <br />Heavv Me~al. <br /> <br />Bard Creek was a fishless montane stream that was known ~o have eleva~ed <br />levels of heavy metals due to pas~ mining ac~ivi~y. Experimen~al s~ocking of <br />greenbacks in~o ~he fishless habi~a~ of Bard creek indica~ed tha~ greenbacks <br />stocked at cver 25 mm in length will survive ~o ma~urity and spawn despite. <br />elevated ccncentrations of heavy metals. However, eggs from mature fish <br />deposi~ed by late June did no~ ~o survive to the fall in Bard Creek. As <br />Woodward found with low pH and elevated aluminum levels, ~he swim-up and <br />alevin stages may be the most sensitive to elevated levels of heavy metals. <br /> <br />Manaaement Practices <br /> <br />Fish CUlture <br /> <br />Although ~he stocking of cultured nonnative salmonids almost resulted in the <br />extinction of the greenback, the greenback was one of the earliest fish to be <br />reared in Federal hatcheries. In 1889, the Leadville National Fish Hatchery <br />was established near Leadville Colorado, and some of its original objectives <br />were tc rear greenbacks and yellowfins. Both subspecies were obtained from <br />waters adjacent to the hatchery and moved by wagon to the hatchery to be used <br />as broodstock. Eggs of both subspecies were taken from Twin Lakes. However, <br />the greenback and yellowfin cutthroat trout did not adapt well to captive <br />rearing, and lccal citizens were so displea~ed with the hatchery spawning <br />traps in Twin Lakes that they were "blown out with dynamite" (Tulian 1896). <br />The availability of other species (brcok and rainbow trout) more adaptable to <br />hatchery rearing, and the large scale availability of Yellowstone cutthroat <br />(Q. ~. bouvieri) from Yellowstone Lake, led tc the abandonment of the <br />greenback by early fish culturists as a source of trout for stocking purposes. <br /> <br />A second attempt to rear greenbacks at the Leadville National Fish Hatchery <br />was attempted in 1957 and 1958 using 50 slightly hybridized greenbacks from <br />the Big Thompson River in Forest Canyon, RMNP, and 26 pure greenbacks from the <br />now extirpated Albion Creek population. This project was abandoned due to <br />fish mortality in the hatchery and asynchronous maturation of the remaining. <br />males and females. The project ~erminated with the stocking of the surviving <br />broodstcck intc Florence Creek, Uinta and OUray Indian Reservation, Utah. The <br />greenbacks in Florence Creek were almost totally displaced by brock trout by <br />1978. <br /> <br />south Platte Drainaoe Broodstock. As part cfthe Recovery Plan, another <br />attempt to rear South platte drainage greenbacks wasini~iated in 1977, with <br />the transfer of 64 Como Creek greenbacks to the USFWS, Fish CUlture. <br />Development Center, Bozeman Hontana. This broodstock initially enccuntered <br />the same problems with asynchronous maturation cf males and females, the loss <br />of males due to fungus, and the failure to accept feed in a captive situation. <br />In 1978, males produced milt in April and Hay, but the females matured in July <br />and August. Asynchronous maturation problems were overcome by allowing water <br />temperatures to declin~.~~. near 2 C, then allowing the temperature to rise <br />again in the spring. Fungus was controlled with malachite green. The use of <br />variable temperatures and malachite green allowed <br /> <br />12 <br />