Bio-economic Factors Affecting Feasibility of Floating In-pond Raceway Systems: A Stella Modeling Approach
Type of Degreethesis
Fisheries and Allied Aquacultures
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Floating in-pond raceway (FIPR) systems have the potential to efficiently compete with conventional ponds in their ability to produce large quantities of fish profitably. However, little is known about the biological and economic capabilities of these systems, so this thesis investigates a bio-economic modeling approach to help researchers better understand the system and determine what factors most affect its potential. Findings from model simulations provide insights into what field research areas are most important to conduct. A bio-economic model was developed to simulate the stocking, grow-out and harvest of hybrid striped bass (HSB) in an FIPR. HSB were chosen as a model species because FIPR field trials in West Alabama were already incorporating this species and because their relatively high market value ($7.00/kg and up). System/species feasibility was analyzed in terms of HSB biomass production and net returns through the process of completing four modeling objectives with water temperature dependent fish growth at the core of the developed model. Objectives explored include stocking density and density dependent mortality rate relationships, influence of stochastic loss events, fingerling stocking size and date of stocking relationship to final harvest, and using the bio-economic model to construct longer term production plans that maximize net returns. At this stage, data produced by the bio-economic model simulations is not intended for direct use by producers in making production decisions, but to explore what bio-economic factors most affect the feasibility of the floating in-pond raceway systems and to use this information to prioritize where further field research is needed to improve model accuracy and value as a management tool. Eventually, as field trials fill current gaps in knowledge, the refined model will be useful in making on-farm decisions to improve the production efficiency and operation profitability. Results from the four objectives indicate that understanding fish growth rate as it relates to seasonal water temperature and species specific biology is essential to producing an accurate model. Secondly, a better understanding of density dependent mortality is needed to determine stocking densities that optimize system performance and maximize net returns. Third, stochastic mortality loss events were identified as critically important factors affecting economic feasibility and further field research is needed to refine the frequency and magnitude parameters in the model. Finally, analysis using the bio-economic model indicated that overwintering HSB in the FIPR is expensive, especially in the case of holding larger fish. As growth parameters used in the model are refined through field research the model can become a useful tool for producers and researchers in making profit maximizing HSB FIPR system management decisions.