Fish Community Characteristics And Potential Production In Xiannv Lake

Located in the southwest of Jiangxi Province, Xiannv Lake is the second largest reservoir with approximately 50 km2 water area. The reservoir contains many important sources of fresh-water organic aquatic products and provides drinking water for the residents in Xinyu City, Jiangxi Province. And provide some crucial functions of unban ecosystem. In recent years, the water conservancy projects increased year by year, but the water resources had been dwindled. In this background the strategy that water conservancy is changing from engineering style to resource style was proposed by The Ministry of Water Resources. In order to analysis the fishery of Xiannv Lake, the author had investigated three times which contained the species composition, species diversity, the growth of dominant species, the relationship between the community structure and environmental factors respectively from October 2014 to August 2015. And intend to provide some scientific knowledge for fishery resources management and protection of ecological environment. The main results were as follows:1. In this investigation, totally 44 fish species were collected, belonging to 4 orders, 10 families and 34 genera in Xinanv Lake. Compared with the survey results by Liu Shiping in 1980, 15 species were new record, and 6 species record were not found at this survey. The dominant species are Pseudobrama simoni, Carassius auratus, Hemiculter leu- cisculus, Xenocypris davidi, Cyprinus carpio in Xiannv Lake.2. The results showed that the diversity of fish community and richness in Wulong Lake were higher than Qianyang Lake. As for the analysis of ABC curve the fish community were in serious disturbance in Xiannv Lake. The by-catch dominated by small fish except for the cultured fish.3. The results of RDA(Redundancy analysis) revealed that the important environmental factors were obvious difference in three seasons. The major environmental factors affected fish distribution were depth and total nitrogen in autumn, depth and dissolved oxygen in spring, the main environmental factors were water temperature and depth in summer. Depth was the crucial environmental factor that affected the fish community in Xiannv lake.4. Relation curves of weight and length of dominant species in Xiannv Lake, including Pseudobrama simoni, Carassius auratus, Erythroculter ilishaeformis, Hemiculter leucisculus, Odontobutis obscurus, Hypophthalmichthys molitrix,Hypophthalmichthys nobilis, were fitted. And according the relationship between the age and weight of Odontobutis obscurus, it was concluded that the inflection point of age is 2.956 years and the inflection point of body length was 11.38 cm and weight was 23.22 g. The Ricker body condition index revealed the Carassius auratus’ s index was the highest and the Erythroculter ilishaeformis’ s index was the lowest.5. The average value of The CPUE was 94 kg/d in Xiannv Lake. The highest value appeared in the spring of 2014, the second value was in autumn of 2014 and the lowest value in summer of 2015. According to the annual plankton biomass, the potential production of fish was 5030 tons one year. The reasonable stock of Hypophthalmichthys molitrix and Hypophthalmichthys nobilis were 1.4 milliom and 4.3 million each year.