摘要：Relative weight (W r ) was originally developed to assess the physiological status of largemouth bass. Later it was expanded to other centrarchids and, more recently, to non-centrarchids without consideration of how well the concept may fit other taxa. Our goal was to compare the ability of W r , to convey physiological information among species. We considered the following alternative hypotheses: that the relationship of W r , to physiological status would vary according to phylogeny, according to ecological specialization, or according to morphology. We collected data (water, protein, lipid, liver, gonad and viscera percentages) from 216 fish of four species (bluegill, largemouth bass, black crappie, chain pickerel) from two Virginia impoundments. All but one population-specific multiple regression model explained a significant amount of variation (F > 2.31, P 0.45). Correlations of lipid to W r were lowest for bluegills (r 2 = 0.11 and 0.15). Variables describing energy storage and short-term growth were positively related to W r in all species; however, the strength of this correlation coincided with trophic role. We concluded that differences in physiology and life history affect interpretation of W r (and other whole-body condition indices) among species. Further, W r , may convey less physiological information for ecologically plastic species (e.g., bluegill) if they are treated as a homogeneous population.
