A plant and method of cultivation for sea cucumber <i>Apostichopus japonicus</i> (Selenka, 1867)

Abstract

A plant and method of the sea cucumber cultivation have been developed and successfully tested. The technology allows to grow sea cucumber Apostichopus japonicus (Selenka, 1867) from juveniles of the current year to adults of commercial size on grounds in unprotected water areas and bottom landscapes unfavorable for habitat of this species. The plant consisted of 5 open-type cages with the size 20x20x1 m mounted on the sea bottom and occupied the area of 400 m2 each (2000 m2 in total). The tests were carried out from the fall of 2018 to late November 2023. After the first two years, only 20.5 % of initial number of resettled factory juveniles had survived, then the number of sea cucumbers stabilized and their distribution density was on average 2.7 ind./m2 (364.4 g/m2) by the end of the experiment. The stock in the cages was replenished annually by larvae from the natural larval pool that was estimated in 6.9 % per year. Monthly weight gains were on average 2.6 g in the last three years of cultivation, though sea cucumbers grew in 3−4 times slower in winter than in summer. The body weight of sea cucumbers by the end of the experiment was 143.9 g/ind., on average. After 5-year exposition, the portion of commercial-sized sea cucumbers (weight ≥ 130 grams) in the cages reached 58.5 % by number and 74.7 % by biomass; their average body weight was 183.6 g. The density of such sea cucumbers distribution in the bottom open-type cages of the plant was 1.5 ind./m2 (272.2 g/m2), on average. Total yield of commercial-sized sea cucumbers harvested from the plant in late November 2023 was 435 kg.