ABSTRACT: Information on the movements of highly migratory species is important to understand their ecology, including habitat use, population connectivity, and stock structure, to implement appropriate management and conservation measures. The blue shark Prionace glauca (Carcharhinidae) is highly migratory, has a global distribution, and is ecologically and economically important as one of the most abundant apex marine predators; however, the migration patterns of pregnant females are unknown. Here, we used pop-up satellite archival tags to elucidate seasonal migration of pregnant blue sharks in the northwestern Pacific. Of 24 tagged adult females, archival data were subsequently obtained for 21 individuals (141.1-243.3 cm precaudal length). Based on ultrasonography or analysis of sex steroid hormones, 17 of these females were confirmed to be pregnant at the time of release. Females with small embryos moved in a northeasterly direction, from subtropical (10-30°N) into temperate (30-40°N) waters during autumn and the following spring; 2 of these females returned to subtropical waters in spring and summer. In contrast, females with large embryos moved in a southwesterly direction, from temperate into subtropical waters during spring and autumn. Tagged sharks also showed regional differences in diving behaviors, reflecting thermal habitats in the ocean environment. Our findings indicate that pregnant blue sharks undergo a seasonal northeast-southwest migration within a year to give birth to pups in productive temperate waters. This is the first report on seasonal reproductive migration of pregnant blue sharks in the global ocean.

中文翻译：

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西北太平洋孕妇蓝鲨普氏金龟的季节性迁徙

摘要：有关高度迁徙物种运动的信息对于了解其生态学（包括栖息地使用，人口连通性和种群结构），实施适当的管理和保护措施非常重要。蓝鲨Prionace glaucachar科（Carcharhinidae）高度迁徙，分布于全球，在生态和经济上均是最丰富的先头海洋捕食者之一；但是，怀孕女性的迁移方式尚不清楚。在这里，我们使用了弹出式卫星归档标签来阐明西北太平洋怀孕的蓝鲨的季节性迁徙。随后，在24位加标签的成年雌性中，获得了21位个体（前尾长141.1-243.3 cm）的档案数据。根据超声检查或性类固醇激素分析，这些女性中有17名在释放时被确认怀孕。具有小胚胎的雌性在秋季和次年春季从北亚热带（10-30°N）进入温带水（30-40°N），向东北方向移动；这些雌性中有2例在春季和夏季返回亚热带水域。相反，在春季和秋季，具有大胚胎的雌性向西南方向移动，从温带进入亚热带水域。被标记的鲨鱼在潜水行为上也表现出区域差异，反映了海洋环境中的热栖息地。我们的发现表明，怀孕的蓝鲨在一年之内经历了季节性的东北-西南迁移，从而在温带水域生产了幼崽。这是有关全球海洋中怀孕的蓝鲨的季节性繁殖迁移的第一份报告。我们的发现表明，怀孕的蓝鲨在一年之内经历了季节性的东北-西南迁移，从而在温带水域生产了幼崽。这是有关全球海洋中怀孕的蓝鲨的季节性繁殖迁移的第一份报告。我们的发现表明，怀孕的蓝鲨在一年之内经历了季节性的东北-西南迁移，从而在温带水域生产了幼崽。这是有关全球海洋中怀孕的蓝鲨的季节性繁殖迁移的第一份报告。