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conducted with the Northern squawfish (P. oregonensus) <br />to conserve the adult Colorado squawfish on hand. Once the <br />technique is perfected, the olfactory acuity of Colorado squaw- <br />fish will be determined by infusion of several standard chemicals <br />such as sodium chloride for which detection threshold information <br />is available for other fish (Nara 1971). Because thresholds <br />determined by physiological means (the EEG technique) can be <br />higher than those determined behaviorly, we also propose to <br />conduct whole organism studies with chemicals that elicit an EEG <br />response. The heart rate of Colorado squawfish will be <br />conditioned to various concentrations of each chemical by using <br />electric shock. If the fish smells the chemical during <br />conditioning the heart rate slows with the addition of the <br />chemical in anticipation of the shock (Hirsch 1977). The level of <br />detection between EEG and whole organism studies will be compared <br />to evaluate the utility of the EEG technique in determining <br />olfactory acuity. <br />To determine whether Colorado squawfish presently in <br />captivity can distinguish natal waters, EEG patterns from fish <br />held at Utah State University and Dexter National Fish Hatchery <br />will be monitored during exposure to water from Willow Beach <br />National fish Hatchery (their natal water), and waters from other <br />i <br />rivers. If available, one or more wild mature adults will be <br />captured over the known squawfish spawning site on the Yampa <br />River (Archer and Tyus 1984) and will be exposed to water from <br />several rivers to see if they recognize water from the Yampa <br />River site. <br />Finally, we propose to imprint Colorado squawfish fry and <br />3