Selectivity study on Y-shaped exclusion device for mantis shrimp and swimming crab in Chinese stow net

Y-shaped exclusion device can improve the selectivity of Chinese stow net effectively.In order to study the selectivity difference of barrier spacing at different sizes, 10-mm, 15-mm and 20-mm barrier spacings were set in this trial.The trial was carried out in Shengsi, Zhoushan in December, 2015, and the dominant species of the catches were mantis shrimp (Oratosquilla oratoria) and swimming crab (Portunus trituberculatus).We then analyzed the selectivity on Y-shaped exclusion device for the mantis shrimp and swimming crab with different barrier spacings based on the combined net data.The results show that the selectivity index L₅₀ of mantis shrimp and swimming crab increased with increasing barrier spacings, while the selection range (SR) of mantis shrimp and swimming crab decreased with increasing barrier spacing, which indicates that the Y-shaped exclusion device can be used to release the crustaceans, such as mantis shrimp and swimming crab.However, the appropriate barrier spacing still needs further study.