Analysis of compound culturing pond build based on Ecopath model

Aimed at analyzing how to build a fresh water recirculating ponds aquaculture system from energy quantization point of view, separated pond and sequencing pond were selected in Pond Ecological Engineering Research Center, Chinese Academy of Fishery Sciences (Shanghai, 30°57′1.89″N, 121°08′52.21″E), as well as a traditional pond (control pond). According to a whole-year data tested in 2016, energy flow characteristics of three kinds of fresh water recirculating ponds aquaculture system were discussed by applying software Ecopath with Ecosim 6.5. The results show that ecotrophic efficiency of fodder the highest in traditional pond (EE=0.77), separated pond (EE=0.75), sequencing pond (EE=0.99). Feed coefficient of traditional pond, separated pond, sequencing pond were 2.5, 2.8, 1.6, separately. These indicated that sequencing ponds which feeding amounts were distinguishing among different size specification were more advantageous to feed conversion. Ecotrophic efficiency of cladocerans, copepod, rotifer in traditional pond, separated pond, sequencing pond were 0.7/0.09/0.39, 0.8/0.02/0.12, 0.77/0.89/0.07, separately. This suggested that cladocerans could be used effectively by system. But different culturing modes can affect the ecotrophic efficiency of zooplankton. In addition, ecotrophic efficiency of rain group and bottom sediment group both less than 0.1, indicated that the energy from rain group and bottom sediment group could not be used effectively by system. Niche overlap analysis suggested that prey overlap index of separated pond were the highest and predator overlap index of sequencing pond were most highest than others. It means that the intensity of bait competition in seperated pond were the largest and sequencing pond had more pressure from the predator prey. Seperated pond could reducethe intensity of bait competition by strengthening regional water flow. Lindeman spineanalysis showed that the dominant energy flow ways of fresh water recirculating ponds aquaculture systemwere grazing food chain. System characteristic analysis suggested that the system maturity of separated pond and sequencing pond were superior to the traditional pond, means that it is possible to change the traditional single fragile pond ecological and improve system diversity by constructing compound aquaculture mode.