Ecological and Economical Analysis for Implementing Integrated Multi Trophic Aquaculture (IMTA) in an abraded area to recover aquaculture production in Kaliwlingi, Brebes, Indonesia

Coastal abrasion is a phenomenon with large ecological implications at global level and with major impact on the farming production and farmers‘ income in many areas, such as in the peculiar case of the village Kaliwlingi, of Brebes Regency, west of the Central Java Province, Indonesia. In order to ensure long term sustainability of aquaculture production in the area, the present study proposed an integrated approach based on the analysis of significant ecological and economic factors important in the decision making process of selecting the best suitable sites to perform this activity. Three species were chosen to be cultivated in accordance with the concept of Integrated Multi Trophic Aquaculture (IMTA), which will bring benefits both toecosystem by maintaining its balance and to farmers’incomes as well. These species are: the milkfish (Chanos chanos), the seaweed (Gracilaria verucosa), and the green mussel (Perna viridis). By using Geographic Information System (GIS) and based on the results of the ecological analysis it has been shown that 2,759 ha of the study area could be deemed as suitable for sustainable cultivation, while 1,852 ha - less suitable. The Specific Growth Rate (SGR) (%.d-1) of C. chanos, P. viridis and G. verucosa in the Suitable area were 2.67 ± 0.1, 0.57±0.1.89, and 3.65 ± 0.21, respectively. To determine the potential production of the abraded area, the mass yield was calculated. The production (tons) in the suitable area yielded 755 tons of milkfish, 525 tons of green mussel and 952 tons of seaweed. In addition, the results of economic analysis showed a B/C ratio of 1.7 million IDR with Payback Period of 2.7 cycles and Break Even Point of 5,612,350 IDR. However, at less suitable area, due to the ecological limiting factors, the aquaculture production was lower, as well as the economic efficiency.