葛洲坝至古老背江段鱼类的水声学调查

2004年10月~2006年5月利用Bisonics DT-X科学回声探测仪(200 kHz)对葛洲坝至古老背-葛洲坝下游中华鲟(Acipenser sinensis Gray)自然保护区核心江段(30 km)的鱼类进行了5次水声学调查。结果表明：鱼类在该江段中分布呈现不均一性，深潭处分布集中，而急流处分布很少，葛洲坝至艾家河江段鱼的密度明显大于艾家河至古老背江段；在中华鲟产卵日，鱼类在葛洲坝至庙咀江段高度密集，2004年的平均密度达到62.62±24.77尾/1 000 m3，2005年的平均密度达到70.58±37.45尾/1 000 m3；整个江段中，体长60~106 mm的鱼类占有较高比例，约7.0%以上，53 mm以下的鱼类和750 mm以上的鱼类占较低比例，均小于2.0%；调查期间，探测到中华鲟产卵亲鱼，初步估算2004年的资源量约为1 453尾，2005年的资源量约为789尾；95%置信度下分别为1 370~1 537尾、775~803尾。

HYDRO-ACOUSTIC SURVEY ON FISHES IN THE REACH FROM GEZHOUBA DAM TO GULAOBEI OF THE YANGTZE RIVER

From October 2004 to May 2006, hydro acoustic survey on fishes was carried out in the 30 km reach from Gezhouba Dam to Gulaobei in the Nature Reserve for Acipenser sinensis Gray in the Yangtze River with Bisonics DT X Scientific Echosounder (200 kHz). Fishes were distributed not homogeneously, being assembled in deep pools but rarely in saults. Mean densities of fishes in the reach from Gezhouba Dam to Aijia River were obviously greater than those in the reach from Aijia River to Gulaobei. In spawning period of Acipenser sinensis Gray, fishes congregated in the reach from Gezhou Dam to Miaozui, with mean densities being 62.62 ± 24.77 ind./1 000 m3 in 2004 and 70.58 ± 37.45 ind./1 000 m3 in 2005. The proportion of fishes with the body length ranging among 60 mm and 106 mm was higher than other length groups along the reach, accounting for approximately over 7.0% of the total fishes. Moreover, the ratio of fishes with body length less than 53 mm and longer than 750 mm were lower than other length groups in the reach, accounting for less than 2.0%. During the survey period, spawners of Acipenser sinensis Gray were found, with 1 453 estimated in 2004 and 789 in 2005, at 95% confidence limits of 1 370~1 537, 775~803 respectively.