长江安庆段长江江豚抚幼栖息地选择及其与鱼类资源分布相关性研究

SELECTION OF NURSERY HABITATS BY YANGTZE FINLESS PORPOISE IN THE ANQING SECTION OF THE YANGTZE RIVER AND ITS CORRELATION WITH FISH RESOURCE DISTRIBUTION

  • 摘要: 极度濒危淡水鲸类长江江豚(Neophocaena asiaeorientalis) 0-2龄死亡率最高, 提高幼豚存活率对促进长江江豚种群数量回升至关重要。优良的抚幼场所是提高幼豚存活率的关键, 然而, 长江江豚抚幼栖息地的选择目前鲜有研究。本研究基于2023年4月至2025年6月在长江安庆吉阳矶—鹅毛洲江段开展的母子豚分布目视考察, 结合鱼类资源水声学调查探测, 分析了长江江豚抚幼栖息地的选择及其与鱼类资源分布的相关性。目视考察共观察到长江江豚357头次, 观测到母子豚28对, 母子豚出水点位130处, 均为一母一幼。平均每月观察到的幼豚占比为8.2%, 其中5—6月和10—12月观察到的幼豚占比最大, 分别为23.6%和41.4%。核心抚幼区(50%KDE)占研究水域总面积的17.12%, 主要分布于吉阳矶、清洁洲南汊、大渡口江段及鹅毛洲洲头区域, 其共同特征是含有大面积的非航道区域和自然漫滩。87.8%的核心抚幼区与长江江豚核心分布区(50%KDE)重叠, 且均位于长江江豚核心分布区的中心水域。相关性分析表明, 母子豚分布密度与鱼类整体分布密度, 以及体长<10 cm的小型鱼类分布密度均无显著相关性(P>0.05)。以上结果说明长江江豚繁殖存在明显的季节性差异, 抚幼对栖息地质量要求更高, 核心抚幼区为长江江豚最优质栖息地, 并提示鱼类资源并非抚幼栖息地选择的主导因素, 推测这与禁渔后长江鱼类资源的整体恢复有关。本研究揭示的长江江豚核心抚幼栖息地选择和特征可为长江江豚抚幼生境判别和保护提供理论指导。

     

    Abstract: The mortality rate for the critically endangered freshwater cetacean, the Yangtze finless porpoise (Neophocaena asiaeorientalis), is highest between the ages of 0 and 2. Improving the survival rate of calves is crucial for promoting the recovery of the Yangtze finless porpoise population. The availability of optimal nursing habitats is essential for improving calf survival. Nevertheless, the specific waters selected by Yangtze finless porpoises for nursing remain poorly understood. Based on visual surveys conducted from April 2023 to June 2025 along the Anqing section (Jiyangji–Emaozhou) of the Yangtze River, combined with hydroacoustic survey data on fish resources, this study analysed nursery habitats characteristics and their correlation with fish resource distribution. A total of 357 Yangtze finless porpoise sightings were recorded, including 28 mother–calf pairs, all consisting of one adult female and one calf. The mean monthly calf proportion was 8.2%, with the highest proportions observed in May–June (23.6%) and October–December (41.4%). The core nursing area (50% KDE) comprised 17.12% of the total study area, primarily distributed in Jiyangji, the southern branch of Qingjiezhou, the Dadukou river section, and the E'maozhou Head area. These areas share common features, including extensive non-navigation zones, natural shallow waters, and slow-flowing shoals. Approximately 87.8% of the core nursing area overlapped with the core distribution area of the Yangtze finless porpoise (50% KDE) and was consistently located in the central parts of these core zones. No significant difference was between the distribution density of mother–calf pairs and the overall fish density, nor with the density of small fish (<10 cm in body length) (P > 0.05). The above results indicate significant seasonal differences in the reproduction of the Yangtze finless porpoise, with nursery habitats demand higher quality environmental conditions, representing the most favourable sites for the species. Additionally, the findings suggest that current habitat selection for calf rearing is influenced more by other factors rather than fish resources. The habitat selection and characteristics of the core nursing areas for the Yangtze finless porpoise revealed in this study can provide theoretical guidance for identification and protection of calf-rearing habitats for the species.

     

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