Maximum daily consumption (C max ) by adult white crappies Pomoxis annularis (164-532 g live weight) provided ad libitum rations of prey fish was determined at 18, 21, 24 and 27°C. Observed increases in C max between 18 and 24°C followed by a sharp (twothirds) decline at 27°C indicated that a low to negative physiological "scope for growth'* exists for white crappies at 27°C and above. Examination of temperature and dissolved oxygen (DO) profiles from numerous Missouri impoundments for May-August 1991 suggested that white crappies were forced to occupy water of 27-32°C (warm water) in 40% of these impoundments by early June and 85% by early August. White crappies were forced into warm water in only a slightly lower percentage of the deep (>5 m) impoundments we examined than in shallow (^5 m) ones. Evaluation of year-to-year differences (1988)(1989)(1990)(1991) in time periods when white crappies were forced to occupy warm water in Lake Pomme de Terre, Missouri, showed that range (15-64 d) and time of occurrence varied substantially. Our findings suggest that the warm and annually variable summer temperature and DO regimes of many U.S. impoundments may substantially underlie the slow growth rates and among-year variation in size structure and recruitment that are characteristic of crappie populations in these environments.White crappie Pomoxis annularis and the congeneric black crappie Pomoxis nigromaculatus have long been popular sportfishes throughout much of the United States (Hooe 1991). Recently these species have also gained attention as being potentially valuable for aquaculture (Garling et al. 1992). Despite years of interest in these fishes, almost no published information on their bioenergetics exists, including the relations among maximum daily consumption (C max ), temperature, and body weight.Defined relations between C max and temperature for different size-groups of these species have numerous applications to crappie fishery management, including identification of optimal and suboptimal temperatures for food consumption and growth (Binkowski and Rudstam 1994). Estimates of C max for crappies can also be used to estimate 'Present address: Department of Biology, Kansas State University, Manhattan, Kansas 66506, USA. their demand on prey communities (Hartman and Brandt, in press) and, when coupled with food consumption estimates, allow quantitative assessments of feeding environment adequacy (Hay ward and Margraf 1987; Hartman and Brandt, in press). Because equations describing how a species' C max depends on temperature and weight are basic components of fish bioenergetics models (Winberg 1956;Kitchell et al. 1977;Hewett and Johnson 1992), information of this type will also contribute to the development of crappie bioenergetics models with applications to both fisheries management and aquaculture (Knights 1985).We determined maximum daily consumption by adult white crappies (164-532 g live weight) fed ad libitum rations of prey fish at four temperatures from 18-27°C. The response of C max at the upper...

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