An Artificial Habitat and a Method for Cultivation of the Sea Cucumber, Apostichopus japonicus (Selenka, 1867)

An innovative industrial artificial habitat and a method to grow the Japanese sea cucumber, Apostichopus japonicus, from underyearling juveniles to a marketable size at fish farming sites with unprotected water areas and seabed landscapes unfavorable for sea cucumber habitats have been developed and successfully tested in practice for the first time. The tests were conducted from the autumn of 2018 to late November 2023. The artificial habitat consisted of five bottom-set open cages 20 × 20 × 1 m (each occupying an area of 400 m2 on the seabed at the fish farm site, with a total of 2000 m2). After the first 2 years, only 20.5% of the initial number of released hatchery-reared juveniles remained (survived) in the cages. Subsequently, the stocking density of sea cucumbers in the artificial habitat cages varied slightly, and by the end of the experiment averaged at 2.7 inds./m2. Over the last 3 years of growth, the sea cucumbers gained an average of 2.6 g per month, with the rate of body weight increase in winter being 3–4 times lower than in summer. By the end of the experiment, the biomass of the sea cucumbers in the cages was 364.4 g/m2 with an average body weight of 143.9 g. The natural annual input of sea cucumbers in the cages by larvae from the natural larval pool was 6.9%. The proportion of marketable-size sea cucumbers reached 58.5% by number and 74.7% in biomass. The average body weight of marketable-size sea cucumbers (≥130 g) was 183.6 g; their stocking density in the cages was 1.5 inds./m2; the biomass was 272.2 g/m2. In late November 2023, the total yield of marketable-sea cucumbers collected from the artificial habitat was 435 kg.