Recirculating aquaculture system (RAS) is a technology that allows to farm exotic warmwater marine species on-land, with the necessary bio-security for the cultivation of a non-native species, water quality control as well as waste management. Critical farm parameters such as stocking density and survival rate can influence the production plans and costs. RAS operations in Europe should consider farming marine species of fish that are suitable for aquaculture. Reproduction, availability of fingerlings, robust and good growth performers, and known rearing conditions are essential. Additionally, high product quality and a good market potential are decisive. Giant grouper (Epinephelus lanceolatus), a species already successfully farmed in the Australasian Pacific region, appears to be ideally for RAS aquaculture in Europe. Nevertheless, for the successfully cultivation of E. lanceolatus in RAS, on-site experience and data must be gathered. Studies were carried out in view of a commercial cultivation of the species in closed RAS facilities and bio economic simulations were conducted. An important aspect in this investigation was to gather bio economic farming parameters, such as growth and stocking density under RAS conditions, to achieve an economically viable cultivation of the species while optimizing both, water quality and animal welfare.
Growth performance in three different commercially interesting stocking densities (60, 80, and 100kg/m³) for two fish size groups (average weight 105g and 490g) were determined. Stress indicators (blood cortisol) and external appearances of the animals were also assessed. Moreover, circular-economy aspects were taken into consideration, especially new ways of transforming waste products into re-usable materials.
The results showed that the growth performance of E. lanceolatus in RAS was very good, comparable with warmwater species like yellowtail kingfish. In addition, it was determined that the rearing density had no effect on growth, stress indicators, and external appearance of the animals. Moreover, the site-specific bio economical and market analysis conducted, fortify the suitability of E. lanceolatus as a high value aquaculture product, and confirmed that the cultivation in RAS in Europe is possible.
This R&D project was called OptiRAS and is part of the BaMS (Bioeconomy in Marine Locations) project, funded by the Federal Ministry of Education and Research (BMBF) Innovation Spaces Bioeconomy grant.