Decision Support for Freshwater Aquaculture Systems

Abstract

The development of the aquaculture industry has had immense benefits globally but despite this, a lot of attention has been placed in recent years more on the potential for negative impact from aquaculture. As a result, there has been a lot of attention directed towards research and policy directed at mitigating such impact. However, freshwater aquaculture despite supplying about 63% of total aquatic animal production has been given less attention. Freshwater aquaculture provides high-quality animal protein and subsequent improvement in per capita protein consumption in a number of developing countries, production has continued to expand with very high potential for even further growth. Inland/Freshwater aquaculture in some systems also provide many significant ecosystem services, all of which make it imperative to provide adequate tools, techniques, models, and frameworks be put in place to support management, planning and decision-making or improve on existing ones. The study identifies and analyse models, methodologies and tools used in freshwater aquaculture based on different production areas and systems. Consideration is given to open systems and semi-closed and closed systems. For open systems (lakes and reservoirs), existing models and approaches towards establishing environmental carrying capacity are analysed using Scottish lakes (lochs) as a case study. The model providing best fit for use amongst the most commonly used ones was determined to be the static phosphorus model by Dillon and Rigler. The study then considers improvements on this approach by recommending a lake sub-division approach where large lakes or lakes with expected complex flow dynamics are concerned. A second approach taking point sources into account when using the Dillon-Rigler model is recommended along with the land-use data for ensuring that aquaculture is not limited where negative impact can be reduced by considering other sources of nutrients. For the semi-closed and closed systems, a dynamic model was developed applying the sub-module approach to enable flexibility of use. The model can also be utilised as a framework to enable the right kind of data required for decision making to be clearly understood. The model when used thus has production, ‘nutrient and waste’ and ‘water and oxygen’ modules as the main modules the result of which can be fed into other modules for pond systems, flow-through systems and RAS. The initial production system modules are very simple modules but allow for expansion where complexity is required. The main modules were tested and verified using catfish production in Nigeria and the module utilised as a framework to analyse nutrient waste and management scenario in Hungarian Carp production in semi-extensive pond systems. The study therefore provides adequate decision support tools for different freshwater systems.