Effect of Different Feeds on the Growth and Survival of Holothuria scabra (Sea cucumber) in Nursery Culture

Abstract

Increased harvest pressure and local harvesters’ intensifying collection have led to a critical de cline in Holothuria scabra populations in Sri Lanka. Aquaculture provides a practical solution to reduce the overexploitation of sea cucumbers. In Sri Lanka, juvenile post-release survival and growth performance have been scarce. Therefore, this study aims to evaluate the growth performance and percentage of survival of juveniles under different feed treatments along with control setups. The present study was conducted at Suganth Seafood (Pvt) Ltd, Kakkaitheevu, Jaffna. Juveniles (2–3g) were selected randomly from the hatchery and stocked in indoor nursery tanks (120L). Three replicate tanks were maintained for each treat ment (T1, T2, T3) and the control, with a stocking density of 20 juveniles per tank. Varying ratios of three types of seaweeds and sea mud were utilized in feed preparation as follows: Sargassum crassifolium : Gracilaria salicornia : Kappaphycus alvarizii : sea mud in T1 = 4:3:2:1, T2 = 2:4:3:1, T3 = 3:2:4:1, and in the control, sea mud alone (100%) was utilized. Growth performances were evaluated by measuring total body weight, total body length, growth rate, along with survival rate and food conversion ratio. Although all seaweed-based feeds supported 100% survival with moderate growth, the feed containing a higher proportion (40%) of Kappaphycus alvarizii (T3) produced significantly higher growth performance compared to the other treatments (T1 and T2). This was observed in mean weight (14.72 ± 0.39g, p < 0.05), mean length (5.48 ± 0.18cm, p < 0.05), and growth rate (0.39 ± 0.01g/day, p < 0.05). Interestingly, the control setup showed the lowest growth performance. Statistically, there was a significant difference among treatments (p < 0.05), and the K. alvarizii (40%) showed improved growth performance among indoor nursery systems. Therefore, this study suggests that indoor culture using seaweed-based feeds such as Kappaphycus alvarizii seems to be a stable and effective approach for post-release hatchery juveniles in sea cucumber culture.