异常枯水位期鄱阳湖长江江豚分布风险与保护对策

DISTRIBUTION RISKS AND PROTECTION COUNTERMEASURES OF YANGTZE FINLESS PORPOISE IN POYANG LAKE DURING ABNORMAL DRY PERIOD

为研究鄱阳湖异常枯水位对长江江豚(Neophocaena asiaeorientalis asiaeorientalis)生存带来的风险,在2022年丰水位期、枯水位期和极端枯水位期开展了系统的调查。结果显示:丰水位期长江江豚为全湖分散分布,主湖区分布多、通江水道少、支流尾闾中极少;枯水位期长江江豚呈现区域性、聚集式分布特点,并且逐渐向支流的入湖河槽和主湖区北部河槽迁移,砂坑中逐渐增多,入江水道也有分布;异常极枯水位期长江江豚的分布进一步集中,呈现向主河槽集聚、向支流迁移和滞留砂坑的特点,且通江水道监测到长江江豚的分布密度为全年最高。随着异常极枯水位的持续,长江江豚在鄱阳湖分布的范围急剧缩小,在隔离的小水体分布密集,考察发现在松门山瓢头南部砂坑水域分布约110头长江江豚,信江瑞洪大桥下游分布约18头,赣江扬子洲水域分布约20头。受到航运、垂钓等人类活动干扰,还面临饵料资源不足等生存风险。文章报道和比较了2022年不同水位时期鄱阳湖长江江豚的数量和分布,揭示了异常气候情景下的长江江豚分布格局及其适应性,识别了高风险水域和风险因子,结合采取的系列救护行动,提出了异常水位波动时期鄱阳湖长江江豚的保护救护方案。研究结果将为异常水位时期鄱阳湖长江江豚的保护提供新思路,亦可为长江中下游流域异常气候情境下长江江豚的保护提供科学参考。

To study the risks of abnormal dry water levels in Poyang Lake to the survival of Yangtze finless porpoise(Neophocaena asiaeorientalis asiaeorientalis,YFPs),we conducted systematic surveys at high,low,and extremely low water level in 2022.The results showed that,at high water level,YFPs exhibited a widespread distribution across the entire lake,predominantly congregating in the central expanse and showing lesser presence in the river channels and tributaries.At low water level,the distribution of YFPs became more localized and concentrated.They gradually entered the tributaries inlet channels and the northern channels of the main lake,displaying an increased affinity for sand pits and inlet channels.The distribution of YFPs were further concentrated during the period of extremely low water levels,showing accumulation toward the main trough,migration into the tributaries,and retention in the sand pits.Notably,the density of YFPs in the river channel reached its annual peak during this phase.The distribution of YFPs in Poyang Lake decreased sharply as the water level decreased,and YFPs is densely isolated in small water spaces.The investigation found that there are approximately 110 YFPs in the sand pit water area south of Piaotou in Songmen Mountain,approximately 18 YFPs downstream of the Xinjiang Ruihong Bridge,and about 20 YFPs in the Yangzizhou of the Ganjiang River.The YFPs is disturbed by human activities such as shipping and fishing,and also faces survival risks such as insufficient bait resources.This study not only presents the population abundance and distribution of YFPs in Poyang Lake across varying water levels in 2022 but also offers comparative insights into the distribution patterns of YFPs under abnormal climate scenarios.Additionally,it delves into their adaptive capacity and identify high-risk areas and risk factors.Combined with the series of rescue actions,the protection and rescue plan of YFPs in Poyang Lake during the period of abnormal water level was proposed.The results would propose new insights into the conservation of YFPs in Poyang Lake under abnormal water levels and provide scientific references for the conservation of YFPs under abnormal climate conditions in the middle and lower reaches of the Yangtze River.