An ecosystem model for estimating shellfish production carrying capacity in bottom culture systems

A production model has been developed to estimate scallop bottom culture carrying capacity. The model coupled pelagic system, scallop energetics and population dynamics with hydrodynamics. The methodology considers temperature and particle organic carbon (POC) were used to determine the carrying capacity through scallop growth, production and economic benefit. The model was applied to the Zhangzidao culture area in the North Yellow Sea, the largest marine ranching of Japanese scallops Patinopecten yessoensis in China. The studied area was divided into four boxes according to the temperature and depth gradients. The results showed that the model could successfully capture the main characteristics of the observed environmental variables, POC concentrations and biological behaviour of the cultured scallops. The food availability showed seasonal variations. The low temperature had also a great effect on the growth of the scallops in the south area during period of January to July. In contrary, the high temperature would cause high mortality rate of the scallops in the north area in September. Based on the production and profit, the optimal seeding densities were estimated to be 82,500, 105,000, 82,500, 60,000 in. ha−1, respectively in the Boxes1, 2, 3 and 4. There is the potential to increase the seeding density in the northeast area (Box 2), while the southwest area has already exceeded its capacity. The successful application of the model suggests that it could be used as a management tool for estimating the production carrying capacity in the bottom culture systems.