Pre-Growout Culture of Asian Seabass Lates Calcarifer (Bloch) in Low Volume Cage in Brackishwater Ashtamudi Lake Under Participatory mode with Traditional Fisherman

Abstract

Degradation of ecosystem and depleting fisheries resources together lead to poverty and marginalisation of traditional f ishermen depending on open water bodies. Challenges related to depleting fish wealth of Ashtamudi lake has been reported to affect livelihood of f ishermen using traditional methods of f ishing. A pre-growout culture of Asian seabass was initiated in participation with traditional Chinese dip net f ishermen in order to assess feasibility of seabass culture in low volume net cages in Asthamudi lake, Kollam District, Kerala. Fingerlings of Asian seabass (avg wt., 8 g) produced at fish hatchery, Muttukadu experimental station, CIBA, were transported in oxygen packing (5 nos/5 l) involving a transport duration of 18 h. Hundred numbers of seabass were stocked in a low volume net cage of dimensions, 1.5 x 1.5x 1.5 m and mesh size, 22 mm. Fish were initially fed twice a day @ 20% bodyweight initially approximately on trash f ish obtained from the Chinese dip net owned by the f isherman. Periodic samplings were conducted to assess growth potential and survival of the f ish in the small volume cage model. Size based segregation into 2 groups was done at the end of 60 days and the f ish were stocked into two separate cages of equal volume, cage 1 was stocked with f ish above 70 g (40 numbers) and cage 2 with f ish below 70 g (20 numbers). Small seabass below 15 g were separated. At the end of the 90 day pre-growout culture, the fish attained a f inal average body weight of 182.07±10.94 g, with a specif ic growth rate of 3.38±0.08 % day-1, an avg. weight gain percentage of 2175.8±136.7 and an overall survival of 63 %. The average body weight of cage 1 and 2 were 214.04±8.47 g and 95.75±8.75 g respectively. The results showed the feasibility of carrying out pre-growout culture of seabass in low volume net cages and highlights the prospects of adoption of small scale cage culture of Asian seabass as a livelihood option for augmenting the income of the traditional f isherfolk depending on the open water bodies.