Bioeconomic feasibility of aquaponics in South Africa: leapfrogging for sustainable development of freshwater aquaculture.

Food security is being threatened globally due to a combination of factors, such as climate change, anthropogenic pressures and burgeoning competition for limited water and land resources. The need to adopt environmentally and economically sound sustainable food production systems which are adaptable to the prevailing environmental stressors is imperative. Aquaponics sustainably converts aquaculture waste into nutrients for plant uptake resulting in an unconventional food production system which potentially provides an economically viable means of food production. Integrated recirculating aquaculture as adaptive technology is complex and capital intensive, thus, must be financially sustainable. This study, therefore, assessed the bioeconomic feasibility of aquaponics (a branch of aquaculture) in South Africa as a potential leapfrog technology for the rapid development of aquaculture, attainment of food security and local economic development. Quantitative and qualitative SWOT analyses, and key success factors of leading aquaculture players in Africa (Egypt, Nigeria and Uganda) were used as a benchmark to assess the South African aquaculture sector. Qualitative analysis of South African aquaculture sector vis-à-vis the leading aquaculture players in Africa reveals a suboptimal environment that is not suitable to drive costeffective and competitive conventional large-scale commercial aquaculture. Also, inadequate enabling environment due to bureaucratic hindrances towards the implementation of well-crafted aquaculture development policies and framework, and higher operating cost were identified. The quantitative SWOT analysis of key aquaculture players in Africa revealed Egypt was having the highest aquaculture development competitive strengths, and Nigeria showed the highest aquaculture development and market opportunities. Quantitative SWOT analysis of key aquaculture species in South Africa showed trout and tilapia have the highest competitive strengths, while abalone, oyster and marron crayfish showed good market opportunities but weak in competitive strengths. Growth performance of Oreochromis mossambicus and the yields from plants – tomato, pepper and cucumber due to the effects of plant density and stem pruning were assessed in a twin system designed, constructed and operationalized as a low-cost, small-scale aquaponic system. The economic viability of the aquaponic system was assessed using the price trend analysis of fresh produce in South Africa, biomass yield, cost inputs and revenue models using conventional aquaponic cultural methods. Financial performance was determined using financial metrics such as return on investment (ROI), net present value (NPV), internal rate of return (IRR) and profitability. Analyses were modelled to determine the financial performance of the aquaponic system. The growth performance and yield of fish cultured in the aquaponic system showed excellent performance based on FCR (1.25 %), survival rate (97.5 %), LWR r2 (0.945), regression coefficient b (3.1) and condition factor K (1.93). Total and marketable yield of vegetables (tomato, sweet pepper and cucumber) significantly increased (p < 0.05) with a higher plant density of 8 plants /m2 compared to 5 plants/m2. Plants with a higher stem pruning to two and three stems performed significantly better than those pruned to one stem (p < 0.05). The interactive effects of a higher plant density and stem pruning resulted in significant (p < 0.05) higher total and marketable yields with all the plants. Economic analysis of the small-scale aquaponic setup and operation did not present economic feasibility with the adoption of conventional cultural techniques (a revenue model of 59:41 % fish to plant ratio) as a result of the higher operating cost associated with fish production. A fish to plant revenue model of 42 : 58 % ratio (achieved by adopting optimized cultural technique) however, showed marginal economic viability. Plant yield in aquaponics can be improved for higher economic returns through the synergistic optimization of plant density and stem pruning while adopting other optimal cultural management practices. A minimum revenue model of 30 : 70 % fish to plant ratio is recommended for aquaponic operations in South Africa to attain economic feasibility. Aquaponics thus presents optimistic potential to drive sustainable and feasible food production in South Africa with the adoption of viable production and marketing strategies.