Increased Yangtze finless porpoise presence in urban Wuhan waters of the Yangtze River during fishing closures
休漁期間長江武漢市區江豚數量增加
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
漢，中國長江中高度城市化和快速增長的地區
經濟區，歷史上被確定為長江江豚（Neophocaena asiaeorientalis asiaeorientaris）瀕危的空白區，基于
日間目視檢查。然而，海豚的數量明顯增加了自2020年以來的目擊事件。本研究采用被動聲學監測來研究2020年至2022年武漢江豚分布情況。廣義線性模型用于探索航運、水文模式、光照之間的關系強度和海豚生物聲納活動。603天以上?有效監測的天數海豚biosonar檢測的日陽性率達到43%，與喂養有關嗡嗡聲信號占所有海豚生物聲納信號的55%。然而，檢測到海豚存在的分鐘比例為0.18%，這表明雖然海豚可能經常出沒于該地區，但它們的訪問時間很短，主要集中在關于喂養。出現了一個顯著的時間趨勢，表明在冬季（特別是2月）和2022年，海豚的生物空間檢測率較高。此外，時期沒有船只交通與江豚活動增加相關。水文條件和光照水平與江豚活動呈顯著負相關。
具體而言，海豚聲納在夜間、黃昏、夜間和夜間的探測明顯更高，新月相。禁漁令和新冠肺炎都是可以想象的
與疫情相關的封鎖導致江豚在武漢。武漢市城市交通航運快速發展由此產生的水下噪聲污染已成為對海洋環境的重大威脅當地海豚種群。因此，監管機構必須有效應對這一環境壓力，制定有針對性的保護措施，以確保江豚的保護。
關鍵字：
船舶交通、水文狀況、光照強度、被動聲學監測，武漢，長江江豚
