COMPARATIVE ENERGETICS AND THE DEVELOPMENT OF BIOENERGETICS MODELS FOR SYMPATRIC ESTUARINE PISCIVORES

Bioenergetics models for striped bass (Morone saxalilis), bluefish (Pomatomus saltatrix), and weakfish (Cynoscion regalis) were developed from laboratory experiments on metabolism and consumption. Size-specific rates of consumption and metabolism were similar for bluefish and weakfish and higher than those for striped bass. Temperature effects on maximum consumption rate (C-max) differed with fish size. C-max of young fish (30 g) increased with temperature, then declined rapidly at higher temperatures; C-max for larger fish of all three species (100-3000 g) increased rapidly to the maximum rate, but leveled off at higher (25-30 degrees C) temperatures. Results of C-max experiments suggest that extrapolation of the temperature dependency of small fish to larger fish, as is commonly done, may misrepresent potential growth at higher temperatures. Independent model validation using laboratory experiments found consumption estimates (from growth) to be within -1.4 to +4.5% of known values for all species at temperatures above 19 degrees C; however, at 6.9 degrees C consumption by striped bass was overestimated by 20-46%. Model estimates of growth (from consumption) were within -7.1 to +30.1% of known values in all validations. Overall, the growth physiology of the three species appeared to be related to the water temperatures encountered during estuarine residency and production.