长江中游宜昌江段鱼类早期资源现状

为了探明长江中游宜昌江段鱼类早期资源状况,2014年和2015年连续两年于5―7月在长江中游宜昌江段对产漂流性卵鱼类进行监测,期间共采集鱼卵12209粒。通过分子生物学方法共鉴定出27种鱼类,隶属于2目、4科。其中鲤科鱼类种类数最多,占77%;其次是鳅科,占15%;平鳍鳅科和银鱼科最少,均为4%。鉴定出的27种鱼类中,产漂流性卵鱼类有22种。2014年和2015年长江中游宜昌江段产漂流性卵鱼类的产卵量分别为79.1×10~8粒和70.9×10~8粒,其中四大家鱼产卵量分别为5.65×10~8粒和6.13×10~8粒。监测期间共出现7次产卵高峰(2014年4次,2015年3次),集中在6月初及6月中下旬。四大家鱼产卵量日变化与长江流量日变化关联性较强。2014年宜昌断面采集的四大家鱼鱼卵来自采样点上游的葛洲坝下(坝下–庙咀)、宜昌(胭脂坝–云池)和白洋(白洋镇–关州)三处产卵江段,2015年的四大家鱼鱼卵则来自葛洲坝下(坝下–庙咀)、宜昌(胭脂坝–红花套)两个产卵场。和历史资料相比,长江中游宜昌江段四大家鱼产卵场位置略有下移,规模呈减少趋势。建议继续科学适宜地开展生态调度和增殖放流,满足长江中游鱼类繁殖需求。

Status of fishes at the early life history stage in the Yichang section in the middle reaches of the Yangtze River

Surveys were conducted in the Yichang section in the middle reaches of the Yangtze River from May to June in 2014 and 2015 to reveal the current status of the spawning grounds of fishes with pelagic eggs. A total of 12209 eggs was collected in the Yichang section and the eggs were identified by molecular biological methods. The eggs belonged to 27 species in 4 families in 2 orders. Among them, most were Cyprinidae (77%), followed by Cobitidae, accounting for 15%, and Homalopteridae and Salangidae had the least frequent, each at 4%. Of the 27 identified species, 22 were middle drifting fish eggs or 81% of all species. The total of pelagic eggs in the middle reaches of the Yangtze River was estimated to be 79.1×10⁸ individuals and 70.9×10⁸ individuals, and that of the four major Chinese carp species was 5.65×10⁸ individuals and 6.13×10⁸ individuals during 2014 and 2015, respectively. During the surveys, fishes had a total of seven spawning peaks. Spawning peaks occurred in late May and early June. A series of strong tendencies were found for the four major Chinese carp species regarding the amount of daily fish spawning and the daily flow rate. In 2014, the spawning grounds of the four major Chinese carp species was located in the Gezhouba, Yichang, and Baiyang reaches. The four major Chinese carp species were located in the Gezhouba and Yichang reaches in 2015. Compared with historical data, the range of the spawning grounds of the four major Chinese carp species moved downstream and the number of eggs displayed a decreasing tendency in recent years in the Yichang section in the middle reaches of the Yangtze River, where they have gradually decreased. It is suggested that scientific and suitable ecological reservoir reoperation and enhancement is needed, and fish release should be conducted to meet the demand of fish breeding in the middle reaches of the Yangtze River.