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differences in vulnerability are reduced and the selection of food items is then based mostly on palatability and behavior of the prey (providing that the different prey items offered are equal in size and abundance). Thus, by comparing food habits of bass in a pond environment with observations from controlled lab studies, causes for selection of prey may be elucidated. For example, if green sunfish are eaten more readily than squawfish in a confined situation it would be assumed that the green sunfish is -the more preferred food item. If stomach contents of bass from a pond revealed that squawfish are more readily consumed than green sunfish, this would indicate that under the pond conditions, green sunfish are either less plentiful or less vulnerable than squawfish. . Espinosa and Deacon (1973) tested the preference of largemouth bass under experimental conditions for four prey species. Their results in- dicated that the Virgin River spinedace (Lepidomeda mollispinis) was preferred over golden shiners (Notemigonus crysoleucas), goldfish . (Carassius auratus), and waterdogs (Ambystoma tigrinum) and thus might make a good bait species. Although not mentioned in their paper, the Virgin River spinedace is an endangered southwestern fish and the fact that largemouth bass appear to have a penchant for it as a prey item, may have some bearing on why it has become so rare. Similar experimental studies with Colorado squawfish offered to bass under tank conditions should prove useful in interpreting bass food habits under pond condi- tions during squawfish stocking operations. OBJECTIVES General The proposed project addresses two broad goals. The first is to further our understanding of the ecology of Colorado River backwaters and how the introduction of exotic fish species has contributed to the rapid decline of the native Colorado squawfish. The second goal, being of a more applied nature, is to investigate means of increasing survival of young hatchery-reared squawfish when released in future stocking programs. 28