Portunid crab fattening in indigenous re-circulatory cellular units: a sensitivity analysis

A cost effective indigenous re-circulatory vertical cellular unit was developed using HDPE trays (14 L volume) with 200 numbers. In the present study, two fattening trials were conducted for 60 days. In trail 1, soft shelled mud crabs of 200 numbers were stocked at the rate of 1 crab/tray. In trial 2, soft shelled mud crabs of 145 and 55 numbers of soft shelled blue swimmer crabs were stocked. The yield in trial 1 & 2 was 180 and 152 kg respectively with the weight gain percentage of 28.57 and 26.66% with 90% survival. The economic feasibility analysis of trial 1 & 2 for a period of 5 years revealed that the production unit is a viable enterprise with an average annual net income of Rs.7,46,026 - 10,96,026 with an initial investment of Rs. 650,000 suggesting a payback period of 0.59-0.87 years. Cost benefit ratio of 1.02-1.09 at 30% discount rate, internal rate of return and rate of return on investment were 112.10-167.38% and 114.77-168.62% respectively, under the assumptions of constant input and output price. The sensitivity analysis proved that cellular unit can withstand the risk of 30% reduction in production that indicates the financial viability.