长江安庆段春季鱼类群落结构特征及多样性研究

为了解长江安庆段春季鱼类群落结构及物种多样性现状,于2015年4-6月对该江段鱼类进行调查,共采集鱼类36种,隶属于5目、11科、31属;其中鲤科鱼类占优势,占总种类数的52.78%。按生态习性划分,定居性鱼类占总种数的88.89%,江湖洄游鱼类占总种数的11.11%;按栖息空间划分,底栖鱼类最多,占总种数的50.00%;按摄食类型划分,杂食性鱼类最多,占总种数的44.44%。鱼类优势种为鲇(Silurus asotus)、鲫(Carassius auratus)和贝氏歺又鱼(Hemiculter bleekeri)。渔获物中小型鱼类占据较大比例,大型鱼类比例偏低、规格偏小。Shannon-Weiner多样性指数、Margalef丰富度指数、Simpson优势度指数和Pielou指数均值分别为2.114、3.476、0.248和0.670。与历史资料相比较,鱼类优势种的数量占比降低,群落多样性、丰富度较高,均匀度较为稳定,但个体小型化现象依然存在,渔业资源仍有衰退趋势。建议强化禁渔措施,确保安庆江段渔业资源的可持续利用。

Spring Community Structure and Species Diversity of Fish in the Anqing Section of Yangtze River

The Anqing section of the lower Yangtze River, with a length of 243 km, is located in Anhui Province. It is rich in fishery resources and includes several important ecological areas, including the Yangtze finless porpoises Nature Reserve and the National Germplasm Resource Protection Area for Coilia ectenes and is important for fishery resource protection in the Yangtze River. Spring is spawning season for most fish species in the Yangtze River and understanding the fish community structure and diversity in the spring will allow better conservation of fishery resources. In this study, spring fish community structure and species diversity in the Anqing section was investigated, based on monthly fishery resource surveys from April to June in 2015. The objectives were to characterize the fishery resource status post-construction of Three Gorges Project and provide scientific evidence for fishery resource evaluation and support of conservation projects. Fish were collected for 10 days in the middle of each month in four areas by several methods (weir net, 1 cm mesh; staked bamboo cage, 0.5 cm mesh; drift gill net, 6 cm mesh). Fish collected were identified by species and body length and weight were measured. A total of 36 fish species from 31 genera, 11 families and 5 orders were collected during the investigation, with dominance by Cyprinids (52.78% of total species). The dominant species were Silurus asotus, Carassius auratus and Hemiculter bleekeri. Small and medium-sized fish made up a large proportion of the total fish collected. According to spawning habit, nonmigratory species accounted for 89.47% of the total and migratory species (anadromous and amphidromous) accounted for 11.11%. According to habitat, benthic species were most abundant, accounting for 50% of the total. According to feeding, omnivorous species accounted for 44.44%. The mean values of Shannon-Weiner diversity index, Margalef richness index, Simpson dominance index and Pielou evenness index of the fish community were, respectively, 2.114, 3.476, 0.248 and 0.670. Compared with historical data, the proportion of dominant species decreased, the diversity and richness of fish community was much higher and community evenness was stable, but the trend of miniaturization continued and the fishery resource clearly declined. For these reasons, a strict ban on fishing is recommended to sustain fishery resources in the Anqing section of the Yangtze River. Continuous monitoring of fish resources is also recommended to better understand the dynamics of fishery resources and support implementation of protection and conservation measures.