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.