半自然水域中长江江豚食性与摄食行为的初步观察

2001 年4 月至2002 年3 月, 观察5 头系上标记的长江江豚在夹江中的摄食行为。结果表明: 长江江豚在半自然水域中饲养适应期大约需要两个月, 豢养初期其体重下降幅度约13.8 %; 从经济和适口性来看, 供饲饵料中以鲤鱼最合适, 夹江投放鱼苗应以草鱼、鲢鱼为主。建立人工投食后, 长江江豚日食量在夏季仅占体重的4.1 %、冬季约9.5 % , 均数约6.3 % , 比池内人工饲养下的日食量至少低3 % , 因此夹江中豚类活动能量有1/3 来自自由捕食; 长江江豚每天上午和下午的摄食速度差异显著( P < 0.05) , 推测其夏季野外捕食发生在清晨或傍晚, 冬季在中午。

Preliminary Observations on Feeding Behavior of Finless Porpoises in a Semi-nature Reserve of Yangtze River

Between April 2000 and March 2002, we observed feeding behavior of the five finless porpoises ( Neophocaena phocaenoides asiaeorientalis ) in a Semi nat ure Reserve of Yangtze River. Our results indicated that the porpoises required about two months to adapt to the environments of the semi nature reserve. At th e beginning of the captivity, most of their body weights were decreased by about 13 8%. In view of the economics and edibility of their baits, common carp ( Cy pri nus carpio ) was considered the best, however, grass carp ( Ctenopharyngodon i dell us ) and silver carp ( Hypophthalmichthys molitrix ) should be the first choi ce to be released into the semi nature reserve. After feeding them in captivity, dail y food consumption of the dolphins averaged 6 3% of their body weight annually; and with only 4 1% and 9 5% of their body weights during summer and winter mon th s, respectively. This was 3% less than they were kept in the pool indicating tha t they obtained one third of the energy required from the reserve. Variations o f feeding rates of the porpoises in the morning were significantly different from the feeding in the afternoon ( P <0 05). The feeding in the reserve durin g sum mer occurred at dawn or dusk while feeding during winter often appeared in the a fternoon.