牛山湖小型鱼类群落结构特征及生物量估算

于2002年9月至2003年7月使用围网作为采样工具,对长江中游典型浅水草型湖泊牛山湖的小型鱼类进行了季度定量采样,研究其群落结构特征并估算优势种类在全湖的密度和生物量。依据水生植被状况将该湖划分成黄丝草聚草生境、黄丝草生境和裸地聚草生境,鱼类采样在这3种类型生境中进行。研究期间围网共捕获27种、12 636尾鱼,其中20种属于小型鱼类,体全长分布在19 mm和239 mm之间;以相对重要性指数计,鳑鳑高体(Rhodeus ocllatus)、红鳍原鲌(Cultrichthys erythropterus)、彩副(Paracheilognathus imberbis)、麦穗鱼(Pseudorasboraparva)、小黄黝鱼(Micropercops swinhonis)、似(Toxabramis swinhonis)、兴凯(Acheilognathus chankaensis)和子陵吻虾虎鱼(Rhinogobius giurinus)被视为优势小型鱼类,它们占围网渔获物总数量的91.1%。Zippin法估算结果显示,8种优势小型鱼类的密度和生物量具有明显的季节性波动,它们的年均总密度为3.992 ind/m2,年均总生物量为6.073 g/m2。作者认为合理放养食鱼性鱼类、优化鱼类群落结构是开发利用长江流域湖泊小型鱼类资源并提高渔业产值的有效途径。

Characteristics of community structure and biomass estimates of small-size fishes in Niushan Lake, Hubei Province, China

Small-size fishes that have a short lifespan and high growth rate are important members of aquatic communities.Despite having relatively low commercial value,they often serve as forage fish for more commer-cially important species.Furthermore,small fish species are potentially key determinants of aquatic ecosystems.We evaluated the species composition,density,and biomass of small-size fishes in Niushan Lake,a typical shal-low macrophytic lake along the middle reach of the Yangtze River.Based on macrophyte cover conditions,the lake was divided into three major habitat types: Potamogeton maackianus and Myriophyllum spicatum habitat(H1),P.maackianus habitat(H2),and uncovered/M.spicatum habitat(H3).Fish were sampled quantitatively in the three types of habitat using block nets that were placed seasonally between September 2002 and August 2003.We captured a total of 12 636 individuals comprising 27 fish species,among which 20 species were classified as small-size fishes.The total length of these small-size fishes ranged from 19 to 239 mm.Based on an index of rela-tive importance(IRI),Rhodeus ocllatus,Cultrichthys erythropterus,Paracheilognathus imberbis,Pseudorasbora parva,Micropercops swinhonis,Toxabramis swinhonis,Acheilognathus chankaensis,and Rhinogobius giurinus were the dominant small fish species,collectively accounting for 91.1% of the total catch.The Zippin’s removal method was used to estimate density and biomass of the eight dominant small-size fishes in each season and throughout the whole year.We observed seasonal variation in the calculated density and biomass.For the entire year,average total density and average total biomass of the eight dominant small-size fishes were 3.992 ind/(m2?year) and 6.073 g/(m2?year),respectively.Our results provide baseline information that is essential to the long-term monitoring of small-size fish communities in the shallow lakes in the Yangtze River basin.We suggest that targeted stocking of piscivorous fishes(e.g.,mandarin fish Siniperca chuatsi and redtail culter Culter mongo-licus) and optimization of the fish community structure may provide means to exploit and utilize small-size fish resources in the Yangtze lakes.