Releasing capacity of Portunus trituberculatus enhancement in Zhoushan fishing ground and Yangtze river estuary fishing ground and their adjacent waters

In order to study the rationality of Portunus trituberculatus release in Zhoushan fishing ground, Yangtze River estuary fishing ground and their adjacent waters in recent years, we analyzed the energy flow characteristics of the ecosystem in that sea area and estimated the proliferation capacity of P. trituberculatus based on the fishery resources survey data from 2006 to 2014 by constructing the Ecopath model. The results show that the ecosystem was mainly made up by benthos, and shrimps, Trichiurus leptures and P. trituberculatus had higher food utilization rates. The food utilization rates of Chelidonichthys kumu and Trachurus japonicus were relatively low. Four trophic levels can be divided in the survey area, and P. trituberculatus is a medium trophic organism. The total catch was 1.614 t·km^–2 (the catch of P. trituberculatus was 0.057 8 t·km^–2). The total consumption was 280.744 t·km^–2. The total export was 790.396 t·km^–2. The total production was 959.3 t·km^–2. The biomass of P. trituberculatus was 0.125 t·km^–2. The ecological capacity was 1.125 t·km^–2. The proliferation capacity was 1 t·km^–2. It is shown that the primary productivity of the survey area is high, and the marine organisms are distributed in the second and third trophic scales with relatively low ecosystem maturity. There is still a certain releasing space.