Optimal Harvest Timing and Stocking Season for Turbot (Scophthalmus maximus) in Recirculating Aquaculture System: A Bioeconomic Analysis

Turbot (Scophthalmus maximus) is a globally important species in both capture fisheries and aquaculture. With the development of the turbot farming industry in China and several European countries, enhancing its aquaculture eco-economic performance has become a key concern among stakeholders. Turbot is a major species in marine fish aquaculture in China. As the world’s leading producer of farmed turbot, the bioeconomic dynamics of this species under recirculating aquaculture systems (RASs) remain poorly understood, which hinders optimal resource allocation, green development, and industrial upgrading of the turbot farming sector. In this study, a bioeconomic model for turbot cultured in industrial RASs was developed based on empirical production data and published literature. The optimal harvesting strategies under the industrial RAS production mode were analyzed. The results indicated the following: (1) for a two-year grow-out cycle commencing with stocking at the beginning of the year, at a farm-gate price of 7.56 USD/kg, the maximum cumulative profit of 41,846.08 USD occurred at t = 22.69 months, while the maximum monthly average profit of 1937.65 USD/month occurred at t = 20.49 months. The optimal harvesting time for single-batch culture was t = 22.69 months, whereas for continuous culture, it was t = 20.49 months. (2) Extended analysis incorporating fish price variation revealed that higher market prices corresponded to later optimal harvesting times. (3) February to April was identified as the optimal stocking window. Based on the bioeconomic dynamics elucidated herein, this study provides a theoretical foundation for related research and proposes producer-oriented strategy recommendations for reference by relevant stakeholders.