The sea cucumbers are highly prized organisms in Asian markets and the intense capture throughout the world is threatening their wild populations. Aquaculture of sea cucumbers is an emerging activity in several Indo-Pacific countries and it is considered a sustainable alternative to supply high quality products to the avid markets, while relieving the pressure over the wild populations. Attempts to develop sea cucumber aquaculture in Latin American countries are recent but promising. The production of juveniles in the hatchery is a fundamental step towards the development of aquaculture technology for marine invertebrates. The phase between the hatchery period and the growout culture to commercial size is known as nursery culture. This is a fundamental husbandry step in which young juveniles are cultured until they reach a size at which they can be transferred to growout systems. Parathyone braziliensis (Verrill, 1868) is a tropical, infaunal, holothuroid inhabiting intertidal shores along the Brazilian coast, but little is known about its reproduction and life cycle. The present study aimed to evaluate growth and survival of hatchery produced juveniles of P. brasiliensis during nursey culture in suspended system at sea.
Hatchery-produced juveniles of P. braziliensis were transferred to the sea 36 days after fertilization. The study was carried out on a floating barge located in Armação do Itapocoroy (26°47’ S; 48°36’ W), Penha, Santa Catarina, Brazil. Individuals with an average length of 2.51 ± 0.2 mm were transferred to a square wooden structure (45 x 45 x 10 cm) covered with a Nylon® mesh (500 µm opening) on the top and bottom. This unit was stocked with 700 individuals and remained suspended in a horizontal position on the culture raft at a depth of 1.5 m below the surface. External cleaning to avoid clogging of the screens was carried out on a weekly basis using a brush. The nursey culture lasted 120 days and, during this period, 3 evaluations of growth and survival were carried out. On these occasions, the culture unit was transferred to the laboratory where the organisms were gently removed by hand, aided by the use of a brush. The individuals were counted and measured using a digital caliper (n=20). After that, they were returned to a new culture device with the same dimensions as the previous one and transferred to the sea.
The survival and mean length of juveniles recorded in the first evaluation were, respectively, 94.6% and 10.72 ± 3.51 mm, after 37 days of culture in the sea. After 79 days of culture the mean length was 16.7 ± 0.36 mm. After 120 days of culture, the specimens had a mean length of 20.81 ± 4.2 mm and final survival of 92.85%.
This is the first experimental culture of juvenile P. braziliensis and the results demonstrate the feasibility of using a floating suspended system for nursery culture of this species. The high survival and rapid growth recorded in the present study highlights this species as a candidate for aquaculture in Brazil.
Project funded by Fundação de Amparo à Pesquisa e Inovação do Estado de Santa Catarina (FAPESC), edital 12/2020.