Socio-Economics and Cage Culture Practices of Red Tilapia (Tab Tim) at the Taasarn-Bangpla Canal, Nakhon Pathom Province, Thailand

Abstract

Taasarn-Bangpla is a natural canal in Nakhon Pathom province that has been used to divert water from Mae Klong river to Tha Chin river. The recent increase in fish cage culture raised concerns over its environmental impact. A study on fish cage culture in the canal carried out from 2013-2014 consisted of two interrelated aspects: socioeconomics and environmental. This paper reports the results of the study on socioeconomics which included the number of cages, distribution and production, and culture practices. The survey in 2013 found a total of 35 operators with 527 cages. The cages were mostly concentrated in Tung Kraphanghome sub-district of Kamphaeng Saen district with a small number found in Donthoom district. Red tilapia (Tab Tim) was the cultured species with an approximate production of 1,057 tonnes y^-1 from 2 crops per year. Cage culture in the canal first emerged before 2002. The current popularity is a result of private sector promotion through contract farming. Profit margin obtained from successful cage culture has attracted more people to get involved in cage culture. Some farmers practice cage culture as their main occupation while others practiced it as a secondary occupation to earn additional income. The private sector provided technical guidance on how to raise fish, and supplied fingerlings for stocking as well as credit for the essential inputs such as feed and fingerlings. Operators would initially invest in cage construction mainly from their own savings, while other sources come from relatives who provided loans without interest, and/or commercial banks for loans with interest. A floating square metal frame net cage with a size of 5x5x2.5 m³ was the typical cage structure used to stock 30-50 (30-100) g fish^-1 at the stocking rate of 25-30 (16-40) fish m^-3. Fish was raised for 4-5 (4-7) months with commercial pellet feed containing 0% (25-35%) protein, 3 (2-4) times d^-1. Production of 20-28 (10-28) kg m^-3 was achieved from 80-90% (50-95%) survival rate of 700-1,000 (400-1,200) g fish^-1 at final harvest. FCR ranged between 1.2-1.9 (0.8-3.1). The concern on cage culture at the Taasarn-Bangpla canal is related with its sustainability. Low stocking rates, antibiotic use and aeration were evidences indicating environmental changes in the canal. The absence of strict control measures enabled unlimited proliferation of cages for fish farming, resulting in increased fish production. Thus, there is an issue of how current cage culture practices are affecting sustainability, both the environmental and socioeconomic aspects.