Population Monitoring of Yangtze River Finless Porpoises in the Jiangsu Section of the Yangtze River Estuary
The Jiangsu section of the Yangtze River Estuary spans from the Jiangyin Bridge to the mouth of the northern branch of the Yangtze River Estuary,and is heavily influenced by ocean tides,representing the downstream distribution area of the Yangtze River Finless Porpoises(Neophocaena asiaeorientalis).To elucidate the population and the distribution status of the Yangtze River finless porpoises in this region,four visual surveys were conducted on ships in 2023,complemented by applying methods such as fixed-point observation and eDNA monitoring.Based on the observation data from December 2019 to December 2023,a total of 236 observations and 718 sightings of Yangtze River finless porpoises were recorded.From Jiangyin Bridge to Chongqi Bridge,Yangtze River finless porpoises were observed on both sides,with hot spots regions identified in the Wushan River section,Changyin Shanjiang section,and Jiangyin Bridge section.The result revealed a total of 28 groups of Yangtze River finless porpoises observed during the four visual surveys(covering a sample line of 1 274 kilometers),totaling 65 sightings.The encounter rate of Yangtze River Finless porpoises ranged from 0.02 to 0.13 times/km,with an average encounter from 0.05 times/km.Acording to the visible coefficient method,the estimated population size in February,May,September and November for this river section ranged from 14.8 to 64.8,with an average of 38.9 individuals.Yangtze River finless porpoises can be observed throughout the year,being more active in winter and spring.The hot spot regions for Yangtze River finless porpoises feature more natural shorelines and less human interference.In view of the lack of special Yangtze finless porpoise protection area and systematic monitoring and protection measures in the Jiangsu section of the Yangtze River Estuary,suggestions were put forward to improve the monitoring system,increase protection efforts,take the Yangtze finless porpoise hot spot activity area as a key monitoring area and even establish the Yangtze finless porpoise nature reserve.
Yangtze River finless porpoises(Neophocaena asiaeorientalis)Yangtze River estuaryVisual investigationPopul-ation monitoring
NETL
NSTL
万方数据
