Humpback whales鈥� use of memory to time their migration could prove less effective amid climate change
A new study led by 9I制作厂免费 researchers indicates that humpback whales in the southeastern Pacific combine real-time environmental cues with their memories of conditions in their Antarctic feeding grounds to determine when to embark on their annual 10,000-kilometre journey. With climate change accelerating, the researchers warn this strategy may become less effective amid shifting ocean conditions.听
Tracking whale migration through satellite data聽
The research team analyzed eight years of satellite tracking data, from 2009 to 2016, from 42 humpback whales tagged off Costa Rica, Panama and Ecuador. Their goal was to聽 track each individual during their migration to the Southern Ocean in Antarctica and to understand what triggers the whales鈥� southward migration each year. The findings suggest that whales integrate local environmental changes 鈥� such as sea temperature and food availability 鈥� with their long-term memory of ocean conditions in their Antarctic feeding grounds. This helps them time their migration to coincide with the seasonal bloom of krill, their primary food source in the Southern Ocean.听聽
鈥淭hey seem to know that changes happening in their immediate environment are linked to conditions thousands of kilometres away,鈥� said Professor Virginie Millien, a biologist and lead author of the study published in Scientific Reports. 鈥淭his allows them to fine-tune their migration, so they arrive just as their food supply peaks.鈥澛�
A race against a changing climate聽
This built-in timing mechanism has worked for thousands of years, but it is now being tested by rapid climate change. In recent years, warming ocean temperatures and shifting sea ice patterns have affected the start of the krill bloom. This means that even though whales are adjusting their migration, they may not be able to keep pace with these accelerating environmental changes.听
鈥淲e don鈥檛 know how long they鈥檒l be able to keep up,鈥� said Millien. 鈥淓very year since 2016 has been the warmest on record, and that pattern is speeding up. At some point, their memory-based strategy may no longer work.鈥澛�
The study found differences between males and females in their migration patterns. 鈥淢ales tend to travel faster, taking more direct routes,鈥� Millien said. 鈥淔emales, especially those with calves, take longer coastal routes, possibly to avoid predators and allow their young to rest.鈥澛�
Conservation implications聽
The findings underscore the need to protect critical migration corridors and feeding areas, the researchers said. With increased ship traffic along their coastal migration routes, whales face greater risks of collisions and habitat disruption. Co-author Hector Guzman of the Smithsonian Tropical Research Institute has been working on policy measures to reduce vessel speeds in key whale habitats.听
鈥淭his research provides the data needed to inform conservation efforts,鈥� said Guzman. 鈥淚t鈥檚 not just about protecting whales; it鈥檚 about preserving the delicate balance of marine ecosystems.鈥澛�
About the study聽
by Virginie Millien, Nicole Stafiej, Fernando Felix and Hector Guzman was published in Nature鈥檚 Scientific Reports.听
This study was funded by Natural Sciences and Engineering Research Council of Canada (NSERC) the Smithsonian Tropical Research Institute, Secretar铆a Nacional de Ciencia y Tecnolog铆a de Panam谩 (SENACYT), the Candeo Fund at the International Community Foundation, and a private charitable trust as part of the Whales & Climate Research Program.听聽
