Effect of stocking density on shooter formation, growth and survival of Asian seabass Lates calcarifer (Bloch, 1790) during nursery rearing
2023
Solanki, H. G. | Sumara, M. A. K. | Vanza, J. G. | Kailasam, M. | Mahalakshmi, P. | Kumar, Prem | Ujjania, N. C.
Seabass Lates calcarifer is an important brackishwater fish, which thrives and farmed infresh and saline water environment. Differential growth of this species during larval andnursery rearing phases leads to the formation of shooters, which reduces overall survival dueto cannibalism. Therefore, the present experiment was conducted to evaluate the effect ofstocking density on shooter formation, growth and survival of seabass. Hatchery producedseabass seed (total mean length 1.76±0.39 cm; mean weight 0.132±0.10 g) were stocked innet cage hapa (2x1x1 m) installed in brackishwater pond, at four different stocking densities,viz., T1 (800 nos.), T2 (850 nos.), T3 (900 nos.) and T4 (950 nos.) in triplicates. During the45 days of nursery raising, fishes were fed with formulated nursery feed (crude protein: 42%and lipid 8%) at 5 to 8% of body weight three times a day. Initially, the fishes were manuallygraded on 3rd day and later on weekly basis and transferred to separate hapa. Total numberof shooters formed during grading periods (S1, S2, S3, S4 and S5) were counted. It wasobserved that though maximum shooters were obtained from treatment T1 and minimumin treatment T3, the shooter formation among different treatments were not significantlydifferent. The maximum numbers of shooters were obtained during the period from 9 to21 days of rearing in nurseries in all the treatments. A survival of 60% was recorded duringthe present study. Based on the results of this study, it is suggested to maintain stockingdensities of 400-425 m-2 for nursery rearing in hapa. Also, the rearing period from 9 to 21days is significantly critical for ensuring good survival rate. Keywords:Cannibalism, Differential growth, Formulated feed, Nursery feed, Shooters, Stocking density, Survival rate
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