Analysis on the Reproduction of Fenneropenaeus chinensis and Portunus trituberculatus Based on Their Food Sources and Predators in the Laizhou Bay of China

Abstract:

In this study we analyzed the long-term variation of CPUE (catch per unit fishing effort) of Fenneropenaeus chinensis, Portunus trituberculatus and their predators in the Laizhou Bay of China. We also investigated the density and distribution of their food organisms and predators. Data were collected from 6 surveys in 2011 and 2013 and from previous records. We found that the present CPUE of F. chinensis, P. trituberculatus and their predators all largely decreased. During the releasing period, the food rankings of phytoplankton and macrobenthic animals were Ⅴ (very rich) and Ⅳ (rich) respectively. The density of food organisms for F. chinensis was the highest in the Northeast of the Laizhou Bay in May and in the Middle East in June. The density of predators of F. chinensis was the highest in the Middle West in May and in the Southeast in June. In May and June the density of food organisms for P. trituberculatus was the highest in the Southwest and Northeast. The density of predators of P. trituberculatus was the highest in the Middle West in May and in the Northwest in June.