Sea Ranching Feasibility of the Hatchery-Reared Tropical Sea Cucumber Stichopus monotuberculatus in an Inshore Coral Reef Island Area in South China Sea (Sanya, China)

Abstract

Sea ranching of tropical edible sea cucumbers is an effective way to relieve the overfishing stress on their natural resources and protect the coral reef ecosystem, yet only a few species have been applied in the sea ranching practice based on hatchery-reared juveniles around the world. In this study, an 8-month (April to December) sea ranching study for hatchery-reared edible sea cucumber Stichopus monotuberculatus juveniles was carried out at a tropical coral reef island area in Sanya, China. Several growth performance indexes and basal nutritional components were monitored. Results revealed that the sea cucumbers had a growth rate of 0.35~0.78 mm day-1 during the experimental period, reaching 15.9 cm long before winter. The weight gain reached 491.13% at the end, and most sea cucumbers were able to grow to the commercial size (over 150 g WW) in the first year of sea ranching. The overall specific growth rate (SGR) and survival rates were 0.73 and 27.5%. Most of the death occurred in the first month after release (25.0%–37.5%), and this is probably due to inadaptation to the sudden change of the environment from the hatchery to the wild, which is proved by the remarkable decrease in nutritional indexes (amino acids, total lipid, and crude protein). Stable isotope and lipid biomarkers revealed that the food source mainly comes from water deposits (with microbes), Sargassum sanyaense seaweed debris, phytoplankton, and coral mucus-derived organics. The study proved the feasibility of the sea ranching of the hatchery-reared S. monotuberculatus juveniles in the tropical coral reef island area. Also, it is highly recommended that appropriate acclimation operation before release should be carried out to improve the survival rate of this species.

Movement dynamics, sediment turnover and sheltering behaviours of the nocturnal coral reef sea cucumber, Stichopus cf. monotuberculatus

“…monotuberculatus exhibits a distinct diel pattern of diurnal sheltering and nocturnal foraging. Our observations of nocturnal activity in natural habitats concur with studies in captivity (Chen et al 2022) and on artificial reefs (Xu et al 2022), implying that future population assessments of S. cf. monotuberculatus would best be undertaken approximately one hour after sunset when most of the animals have emerged.…”

“…Several recent studies have emerged on the potential for commercial mariculture and sea ranching of this species. One found high growth rates of the sea cucumbers on artificial reefs, with animals feeding on sediment detritus containing food sources such as microbes, algal debris and phytoplankton (Xu et al 2022). In tanks, this species was more active at higher seawater temperatures and tends to move down-current in simulated flow experiments (Chen et al 2022).…”

Integrative Application of Transcriptomics and Metabolomics Provides Insights into Unsynchronized Growth in Sea Cucumber (Stichopus monotuberculatus)

“…As a result, the decline of wild sea cucumber resources may therefore cause a disturbance in the balance of the marine ecosystem. In China, wild resources of S. monotuberculatus are on the verge of depletion [ 12 ], which generates a threat to the health of marine ecosystem [ 13 ]. Therefore, artificial reproduction, releasing, and farming of S. monotuberculatus has become to be a key measure to restore sea cucumber resources and maintain the marine ecosystem.…”