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<br />has been treated with praziquantel for 12-24 hours (UDAF 1997). No standardized methods for <br /> <br />Praziquantel use currently exist and little information is available on dosage effectiveness or <br /> <br />long term side effects on fish. <br /> <br />Praziquantel is absorbed by tapeworms directly from the water. The chemical affects the <br /> <br />tapeworm by breaking down the tegument of the cestode causing it to undergo spastic paralysis <br /> <br />and detach from the intestine of the host. The host then sheds the dead tapeworms as either <br /> <br />whole worms or worm segments. <br /> <br />Drought conditions and low lake levels have caused recent increases in water temperature <br /> <br />being released from Glen Canyon Dam. Because water temperature is known to influence <br /> <br />growth and development of Asian tapeworm (Granath and Esch, 1983a), increased mainstem <br /> <br />water temperatures may permit Asian tapeworm to expand in number and range with <br /> <br />detrimental impacts to humpback chub. No baseline information for tapeworm loads in adult <br /> <br />humpback chub currently exists. A multi-level intake structure has been proposed for Glen <br /> <br />Canyon Dam, which would increase mainstem water temperatures (USDI 1999). Baseline <br /> <br />conditions for tapeworm loads in humback chub need to be established prior to the <br /> <br />implementation of a temperature control device. <br /> <br />The objective of our study was to use bonytail to evaluate the dosage and time needed to <br /> <br />effectively remove 100% of Asian fish tapeworm from threatened and endangered cyprinid <br /> <br />fishes using the drug Praziquantel. This information was then used to evaluate Asian tapeworm <br /> <br />loads in humpback chub inhabiting the Little Colorado River. <br /> <br />Methods <br />Laboratory evaluations. - Red shiners (Cyprinella lutrensis) infected with Asian tapeworm <br /> <br />were collected from the Verde and Salt Rivers and transported to the Rocky Mountain Research <br />