Abstract

Jiangxi Province is one of the most important distribution of Yangtze finless porpoise (YFP). Since the scientific investigation of Yangtze finless porpoise in the whole Yangtze River basin in 2017, there is no report about the comprehensive and systematic investigation of YFP in Jiangxi Province, and the changes and distribution characteristics of YFP are not clear. In this study, we set up 12 investigation routes from November to December 2021, and the synchronous visual survey method was used to investigate the quantity and distribution of YFP, including the Jiangxi section of the Yangtze River, Poyang Lake and the lower reaches of Ganjiang River. The changes of the population quantity and distribution of YFP in Jiangxi Province and the migration relationship between rivers and lakes of YFP were discussed based on historical data. The results showed that 217 groups and 454 of YFP were observed in November, and 236 groups and 569 of YFP were observed in December. Influenced by environmental conditions such as water level and weather, paired-samples t-test showed that there were significant differences in the number of YFP observations between the two surveys (t = –2.23, P<0.05). The distribution pattern of YFP in November and December were basically the same: YFP were mainly distributed in Hukou Shizhongshan-Pengze Sanhao Island in the Jiangxi section of the Yangtze River; YFP can be found in the waters with suitable water depth, and YFP were high-density distribution in the areas among which Wanghuting-Zhuxihe estuary, Duchang shipyard-Huangjin mouse-Sanshan–Piaosan in Poyang Lake. In the lower reaches of Ganjiang River, YFP were found around the fishing village of Yangzizhou. In December, the encounter rates of the two surveys were 1.00 and 1.08/km respectively, which were both higher than those of previous years, therefore, the population of YFP in Poyang Lake and Yangtze River may have increased. Only 3 YFP and 2 YFP were found in the Hamashi and Shizongshan waters of Poyang Lake during the two investigations, which suggests that there has been almost no migration of YFP between the Yangtze River and Poyang Lake during the survey. In the future, it is necessary to further control human activities in the migration waters of rivers and lakes and promote the migration. Zhuxi Estuary-Wucheng is the main distribution area of finless porpoises. In dry season, navigation control of vessels in this area should be strengthened to reduce the impact of shipping and improve the protection effect of Poyang Lake Yangtze finless porpoises. (Article in Mandarin)