安庆西江长江江豚饵料鱼资源评估

安庆西江是长江江豚（Neophocaena asiaeorientalis asiaeorientalis）迁地保护的重要基地，为评估西江长江江豚饵料资源的供给能力，于2016年8月和2017年1月采用水声学探测与电捕取样相结合的方法，评估了西江水域鱼类群落结构和长江江豚可持续利用的鱼类资源。共采集到鱼类5目8科34种，夏季鱼类密度为1.4～5 662.3 ind./1 000 m3，均值为 253.3 ind./1 000 m3；冬季鱼类密度为0.8～2 338.1 ind./1 000 m3，均值为127.5 ind./1 000 m3。基于平均生物量和P/B-系数估算了西江鱼类生产力，并根据Y=0.5P对江豚可持续利用的饵料鱼产量进行了估算，西江可持续供长江江豚摄食的鱼类资源量约为 3 050～40 800 kg/a。为防止凶猛性鱼类种群过度发展与长江江豚争夺饵料资源，建议加强对西江鱼类群落的持续监测，并在必要时进行人工合理调控。 关键词： 西江；水声学；长江江豚；现存量；最大持续产量

Evaluation of Bait Fish Resources for Yangtze Finless Porise in Xijiang Oxbow,Anqing

The Xijiang Oxbow locates in the Anqing section of Yangtze River and is an important ex-situ conservation base for the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis ). In order to evaluate the food-supply capacity for the Yangtze finless porpoise in the Xijiang oxbow, hydroacoustic measurements were performed using a 200 kHz BioSonics DT-X split beam echosounder from August, 2016 to January, 2017, fish community was investigated with electric fishing method at the same time. Fish production was assessed with average biomass and P/珚B, the maximum sustainable yield was evaluated with Y=0.5 P. The results indicated that: a total of 34 fish species were collected in our survey, fish density was 1.4 -5 662.3 ind. /1 000 m3, with an average of 253.3 ind. / 1 000 m3 in summer, while it was 0.8 -2 338.1 ind. /1 000 m3, with an average of 127.5 ind. /1 000 m3 in winter. The standing crop was about 155 000 kg in summer and 101 000 kg in winter. According to morphological characters and spatial distribution of fish, and combined with the feeding selectivity of the Yangtze finless porpoise, there were 22 fish species with a high potential to be palatability bait for the finless porpoise. All those fishes took account for 32.3％ in weight of harvest by the electric fishing and fish resource could be foraged by the finless porpoise in the Xijiang Oxbow is about 30 500-40 800 kg/year. It was suggested that the fish community should be monitored continuously to prevent the piscivorous fishes to overgrow to compete with Yangtze finless porpoise for food.