A MODEL OF FISH BIOENERGETICS AND GROWTH AT THE ORGANISMAL AND POPULATION LEVELS IN LABORATORY AND POND ENVIRONMENTS

摘要

A dynamic model of fish bioenergetics and growth at the organismal and population levels was developed as a tool to study, evaluate and improve the management of fishpond grow-out systems. The model is applicable to freshwater species of fish under laboratory and pond environments.;The organismal model incorporated 5 key variables (body size, temperature, dissolved oxygen, unionized ammonia and amount of food) and 17 growth parameters which define the species of fish used. Fixed and cyclic levels of temperature and dissolved oxygen were considered. Model behavior agreed well with data on the effect of each factor taken singly and data on the combined effects of size and temperature, size and food, temperature and food, and dissolved oxygen and food. To develop a population model, the effects of food distribution and competition were included in the organismal model.;A simple model of pond environment linking management variables (stocking rate, feeding rate, initial size distribution) to environmental factors was developed. The pond environment model was linked with the population growth model to develop a fishpond culture model which was validated with pond data for channel catfish. The fishpond culture model was used to address important questions on aquaculture management.;The model predicted a growing season of 230 days from April 10 through November 27 for channel catfish raised in College Station, Texas. Feeding fish as a function of appetite was superior to feeding fish a fixed fraction of body weight.;Under the regime of food competition, fish weights were more variable, yield was less and the culture period was longer compared to the regime of no food competition. Increasingly higher yields were produced by successively optimizng growth factors as they became limiting at certain levels of production.;A factorial experiment involving stocking rate, initial size and feeding rate was simulated using the model. The relationship of market yield to stocking rate, for any given feeding rate or input size, was described by a downward opening parabola. Hence, an optimum stocking rate exists, above and below which yields are less.