Increased Yangtze finless porpoise presence in urban Wuhan waters of the Yangtze River during fishing closures
休渔期间长江武汉市区江豚数量增加
Abstract Wuhan, a highly urbanized and rapidly growing region within China's Yangtze Economic Zone, has historically been identified as a gap area for the critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) based on daytime visual surveys. However, there has been a noticeable increase in porpoise sightings since 2020. This study employed passive acoustic monitoring to investigate porpoise distribution in Wuhan between 2020 and 2022. Generalized linear models were used to explore the relationship between shipping, hydrological patterns, light intensity, and porpoise biosonar activity. Over 603 days of effective monitoring, the daily positive rate for porpoise biosonar detection reached 43%, with feeding-related buzz signals accounting for 55% of all porpoise biosonar signals. However, the proportion of minutes during which porpoise presence was detected was 0.18%, suggesting that while porpoises may frequent the area, their visits were brief and mainly focused on feeding. A significant temporal trend emerged, showing higher porpoise biosonar detection during winter (especially in February) and 2022. Additionally, periods without boat traffic correlated with increased porpoise activity. Hydrological conditions and light levels exhibited significant negative correlations with porpoise activity. Specifically, porpoise sonar detections were notably higher during the night, twilight, and new moon phases. It is highly conceivable that both fishing bans and COVID-19 pandemic-related lockdowns contributed to the heightened presence of porpoises in Wuhan. The rapid development of municipal transportation and shipping in Wuhan and resulting underwater noise pollution have emerged as a significant threat to the local porpoise population. Accordingly, it is imperative for regulatory bodies to effectively address this environmental stressor and formulate targeted protection measures to ensure the conservation of the finless porpoise. KEYWORDS boat traffic, hydrological regime, light intensity, passive acoustic monitoring, Wuhan, Yangtze finless porpoises
汉，中国长江中高度城市化和快速增长的地区
经济区，历史上被确定为长江江豚（Neophocaena asiaeorientalis asiaeorientaris）濒危的空白区，基于
日间目视检查。然而，海豚的数量明显增加了自2020年以来的目击事件。本研究采用被动声学监测来研究2020年至2022年武汉江豚分布情况。广义线性模型用于探索航运、水文模式、光照之间的关系强度和海豚生物声纳活动。603天以上 有效监测的天数海豚biosonar检测的日阳性率达到43%，与喂养有关嗡嗡声信号占所有海豚生物声纳信号的55%。然而，检测到海豚存在的分钟比例为0.18%，这表明虽然海豚可能经常出没于该地区，但它们的访问时间很短，主要集中在关于喂养。出现了一个显著的时间趋势，表明在冬季（特别是2月）和2022年，海豚的生物空间检测率较高。此外，时期没有船只交通与江豚活动增加相关。水文条件和光照水平与江豚活动呈显著负相关。
具体而言，海豚声纳在夜间、黄昏、夜间和夜间的探测明显更高，新月相。禁渔令和新冠肺炎都是可以想象的
与疫情相关的封锁导致江豚在武汉。武汉市城市交通航运快速发展由此产生的水下噪声污染已成为对海洋环境的重大威胁当地海豚种群。因此，监管机构必须有效应对这一环境压力，制定有针对性的保护措施，以确保江豚的保护。
关键字：
船舶交通、水文状况、光照强度、被动声学监测，武汉，长江江豚
