Mariculture: A sustainable and lucrative alternative for open access fishery

Introduction

In India, open-access fisheries are the primary source of fish supply, but the growing gap between demand and supply has become a serious concern. To meet the increasing demand, fishermen have adopted indiscriminate fishing practices, often disregarding fish breeding and biological replenishment cycles. The introduction of mechanized fishing boats has further aggravated the overexploitation of natural fish stocks, leading to the extinction of several species. This unsustainable approach threatens the long-term viability of fisheries and the livelihoods of fishing communities. To address these challenges, fishermen must adopt alternative practices that reduce the strain on natural fish stocks while providing economic benefits. Cage culture, also known as mariculture, has emerged as a viable alternative. This study focuses on assessing the profitability and sustainability of mariculture in the Udupi district of Karnataka.

Methodology

Karnataka's coastal regions, particularly the districts of Uttara Kannada, Dakshina Kannada, and Udupi, play a significant role in fisheries. Among these, Uttara Kannada boasts the largest estuarine area with 13 estuaries spanning 4,200 hectares, followed by Udupi with eight estuaries covering 1,885 hectares, and Dakshina Kannada with five estuaries over 1,140 hectares. Cage culture is predominantly practiced in Udupi district, particularly by the young fishermen of the Uppunda region. This community has pioneered mariculture by forming an informal cooperative group, named after the Sea bass species they rear. The group primarily cultures sea bass and red snapper fish species. Sea bass fingerlings are procured commercially from the Rajiv Gandhi Centre for Aquaculture in Tamil Nadu, while red snapper fingerlings are caught from local estuaries. Fishermen use various cage sizes, with the common setup involving two small and one large cage. This study gathered data from six fishermen practicing mariculture in this system (2S+L). Information was collected on aspects such as initial investment, the number of fingerlings reared, labor required for feeding, harvesting, and cage maintenance, the type and quantity of fish feed, and the use of medicines to address fish diseases.

Results

The 2S+L system allowed fishermen to simultaneously culture both sea bass and red snapper species. Sea bass were initially raised in small cages for six months. After this period, to facilitate further growth and achieve the desired body weight, half of the sea bass population remained in one small cage, while the other half was transferred to the large cage. The second small cage, now vacant, was utilized for red snapper cultivation. Red snappers were reared for a period of 18 months to reach the target body weight. The total capital investment for the two small cages amounted to ₹71,100 (Table 1). Among the components, the cage bag accounted for the largest share of the cost at ₹35,900, followed by the cage frame at ₹19,200. Additional www.extensionjournal.com expenses included ₹8,000 for the floating system, ₹6,000 for labor, and ₹2,000 for the service system. For the large cage, the total investment was ₹54,330, with component-wise costs as follows: ₹14,400 for the cage frame, ₹25,930 for the cage bag, ₹6,000 for the floating system, ₹1,000 for the service system, and ₹7,000 for labor. In addition, the common infrastructure required for the 2S+L system, including the mooring system and anchoring system, cost ₹2,500 and ₹3,250, respectively. Overall, the total investment for the entire 2S+L system was ₹1,34,380.

Economics of Mariculture of Sea Bass

The economic analysis of mariculture of sea bass using two small cages and one large cage is summarized in

Economics of Mariculture of Red Snappers

After six months of culturing sea bass, the unused small cage was repurposed to rear wild-caught red snapper fingerlings. Variable costs accounted for 77.84% of the total expenditure. Among these, feed emerged as the most significant expense, amounting to ₹1,24,541.25 (48.93%), followed by labor costs at ₹52,331.25 (20.57%). Labor activities included catching fingerlings, feeding, supervision, and harvesting. The interest on working capital was calculated at ₹21,224.70 (8.34%). Fixed costs were primarily driven by depreciation of the cage, which amounted to ₹47,058.75 (18.49%), and interest on fixed capital, which stood at ₹9,337.50 (3.67%). Overall, the total cost of producing red snappers came to ₹2,54,493.45. Red snappers exhibited a low mortality rate of 4.35%. After accounting for mortality, the yield was 990 kg, with an average weight of 1.8 kg per fish. Gross returns were estimated at ₹3,76,200, based on a market price of ₹380 per kg. The production cost per kilogram of red snapper was ₹257.06, while the net return per kilogram was ₹122.94 (Table 3) (Ashwathy and Joseph, 2018) [1] .

Conclusion

The economic analysis of mariculture for sea bass and red snappers demonstrated its profitability and contribution to sustainable fishing practices. Mariculture has emerged as a promising alternative to open-access fisheries, particularly during breeding seasons or biological recruitment periods. This method offers a sustainable solution to alleviate the pressure on natural fish stocks while ensuring financial viability for fishermen.

References

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