Modeling Dress-Out Traits Based on Morphological Traits in the Siberian Prawn, Exopalaemon modestus (Heller, 1862)

Dress-out traits, such as abdominal meat weight and abdominal meat percentage, are difficult to improve through direct selection in aquatic species due to the lack of reliable measurement methods. To facilitate the prediction of these traits from morphological characteristics in live prawn, Exopalaemon modestus, a total of 518 individuals were collected in 2025 from Suyahu Reservoir in the upper Huaihe River, China. After excluding individuals with incomplete appendages and egg-bearing females, 301 prawns were randomly selected for model development, and the remaining 60 were used for validation. Based on integrated grey relational analysis and path analysis, body mass was identified as the most effective predictor of abdominal meat weight (p < 0.01), explaining 92.1% of the variation when used as the sole variable in the model. Residual analysis and cross-validation confirmed the adequacy and applicability of the abdominal meat weight model. In contrast, morphological traits exhibited low explanatory power for abdominal meat percentage, with all traits together explaining only 19.2% of the variance, indicating their inability to effectively predict this trait. Therefore, in breeding programs for E. modestus, indirect improvement in abdominal meat weight can be achieved via direct selection for increased body mass. However, abdominal meat percentage is not recommended as a target trait for genetic improvement.