Marine ranching and fishery stock enhancement in the Xiangshan Bay

In order to establish a marine ranching demonstration area in the Xiangshan Bay for an effective restoration of biological resources and maximum output of fisheries resources in natural waters, habitat for biological resources was built, suitable proliferation species were screened and applied, ranchable species were multiplied and harvested, and a series of assessment and management techniques were applied. Seven groups of reefs consisting of 15 hexagons and 1 000 roundtable frame-type induction reefs were constructed with an area of 25 hm² and space of 53 810 m³. Large algae such as Laminaria japonica, Porphyra haitanensis and Gracilariopsis lemaneiformis were transplanted. Artificial ranch of 80 hm² for algae, floating plane algae beds as majority and three-dimensional floating algae beds as assistance, were built. Twenty million shellfish including Scapharca subcrenata and Atrina pectinata were cultured by bottom sowing; 1.6 million fish such as Pseudosciaena crocea, Sparus macrocephlus, Nibea albiflora and Sebastiscus marmoratus were released annually; and ten million shrimps such as Fenneropenaeus chinensis, Marsupenaeus japonicas were released annually. Survey results show that the degree of eutrophication in ranch demonstration area has decreased, primary and secondary productivity improved significantly, with algae biomass 18 000 kg/hm². Fishery resources exhibited positive response to the marine ranching. Nineteen months after reef deployment, species richness, the total biomass and abundance of demersal nekton assemblage in the impact area were 1.32, 2.04 and 1.49 times higher, respectively, than those in the control areas.