A Dynamic Energy Budget Model for the Non-Continuous and Biphasic Growth of the Pond-Cultured Swimming Crab, Portunus trituberculatus.

The swimming crab, Portunus trituberculatus, is an important mariculture crustacean species in China. To quantitatively characterize its discontinuous and biphasic growth under intensive aquaculture conditions, we developed a modified growth model based on the dynamic energy budget (DEB) theory. The model incorporates a discontinuous growth representation that explicitly accounts for the molting process. Molting events were parameterized using a threshold ratio (α), defined as the carbon weight-to-wet weight ratio, with stage-dependent critical values derived from laboratory experiments and published datasets. Laboratory experiments were designed to estimate the energy-budget-related parameters together with data from the literature. In addition, by introducing a feedback mechanism for the energy demand of ovarian development, a set of κ values was calibrated with data from the literature to reproduce the stage-specific growth determined by ovarian development. The model was validated with growth data from several published studies related to the growth of P. trituberculatus, as well as measurements from the aquaculture ponds. Multiple goodness-of-fit indices (R-square, modeling efficiency, and Theil's inequality coefficient) confirmed that the modified DEB model accurately reproduced both wet weight and ovarian growth trajectories, along with the characteristic non-continuous pattern of molting-driven wet weight increase. The individual growth model can be a useful tool for optimizing the intensive culture practice of the swimming crab in the aquaculture ponds and assessing the environmental impact of crab aquaculture.