Dunlop Rebecca, Gumley Emma, McGrath Ella Holding, Noad Michael
School of the Environment, University of Queensland, St. Lucia, QLD, 4072, Australia.
School of Veterinary Science, University of Queensland, Gatton, QLD, 4343, Australia.
Sci Rep. 2025 Jul 2;15(1):22859. doi: 10.1038/s41598-025-07010-9.
The Southern Ocean ecosystem is undergoing unprecedented environmental changes, which have led to shifts in the primary food source of baleen whales, Antarctic krill. Additionally, many humpback whale populations have rebounded from near extirpation due to historical whaling, increasing pressure on now vulnerable krill populations. Since humpback whales rely on energy reserves built up during their feeding season to sustain them during migration, changes in their food supply are likely to influence their migration strategies. In this study, the timing of the 'return to feeding grounds,' or southern migration, of the eastern Australian humpback whale population was tracked over a 21-year period. Both land-based and acoustic surveys were used to estimate the timing of the migratory peak in southern Queensland, i.e., the week with the highest number of whales sighted or recorded. Land-based surveys recorded all whales, including females with newborn calves, while acoustic surveys recorded singing adult males. Both datasets revealed that the peak of the southern migration has shifted earlier by approximately three weeks from 2003 to 2024. Although this study does not establish causation, it highlights a strong correlation between changes in migratory timing and sea ice coverage in the whales' Antarctic feeding grounds. The observed decline in sea ice area, combined with the large increase in the humpback whale population, are discussed as potential factors contributing to the shift in migratory timing.
南大洋生态系统正在经历前所未有的环境变化，这导致了须鲸的主要食物来源南极磷虾的数量发生变化。此外，许多座头鲸种群已从因历史捕鲸而几近灭绝的状态中恢复过来，这给如今脆弱的磷虾种群带来了更大压力。由于座头鲸依靠在觅食季节积累的能量储备来维持其迁徙过程中的生存，它们食物供应的变化很可能会影响其迁徙策略。在这项研究中，对澳大利亚东部座头鲸种群“返回觅食地”即向南迁徙的时间进行了为期21年的跟踪。同时使用了陆地观测和声学监测来估计昆士兰南部的迁徙高峰时间，即观测或记录到鲸鱼数量最多的那一周。陆地观测记录了所有鲸鱼，包括带着新生幼崽的雌性鲸鱼，而声学监测记录了正在发声的成年雄性鲸鱼。两个数据集均显示，从2003年到2024年，向南迁徙的高峰时间提前了约三周。尽管这项研究并未确定因果关系，但它凸显了迁徙时间变化与鲸鱼南极觅食地海冰覆盖之间的强烈相关性。海冰面积的下降以及座头鲸数量的大幅增加被讨论为导致迁徙时间变化的潜在因素。
