Trophodynamics of the Fish Valenciennellus tripunctulatus. Ill. Energetics, Resources and Feeding Strategy

A model was constructed which relates energy in diet to metabolic requirements for the mesopelagic zooplanktivore fish Valenciennellus tripunctulatus.Linear and Von Bertalanffy growth models were used to explore the energetic consequences of a number of feasible age/growth strategies.Maxlmum efficiencies were obtained with linear growth to about 30 mm in 1 y.Efficiencies declined rapidly for slower growth strategies.It was hypothesized that a n 'annual' life history strategy was optimum based on energetic considerations.Copepod prey in the 1-2 mm size class were an order of magnitude more abundant and over 4 tlmes higher in caloric content than larger size classes.V. tripunctulatus, however, is highly efficient in obtaining calories from larger prey size classes ( 2 4 mm) which contain a high caloric content per individual.The resource field places severe constraints on predator growth and at 38 mm no surplus energy is estimated available from daily ration over and above metabolic requirements.V tripunctulatus should be sensitive to 'nearfield' competitors as well a s 'remote' predators grazing zooplankton populations in different space/time.