Humpback Whales Struggle To Adapt Migration Amid Climate Change

A new study by McGill University researchers has revealed that humpback whales in the southeastern Pacific rely on a combination of real-time environmental cues and long-term memory to determine the timing of their annual 10,000-kilometre migration. This tactic has enabled them to flourish for millennia, arriving at their Antarctic feeding grounds just when krill, their main food, is at its peak. Yet, as global warming gains momentum, scientists say this memory-guided migration pattern may no longer be a safe bet, which could endanger the species.

Researchers looked at satellite monitoring data gathered in eight years from 2009 to 2016 from 42 humpback whales, which were fitted off the three countries' shores, namely Costa Rica, Panama, and Ecuador. The study aimed to observe their migration trends and determine why they migrate into the Southern Ocean. The evidence points toward the fact that humpback whales season their migration to take place both in response to immediate environmental cues—like the sea temperature and availability of food—and their memory of past conditions in the Antarctic. This incredible facility enables them to fine-tune their journey so they reach their feeding grounds while krill abundance is at its peak.

They appear to be aware that changes occurring in their immediate surroundings are connected to conditions thousands of kilometres away," said Professor Virginie Millien, lead author of the study. "This enables them to adjust their migration, so they arrive at the same moment that their food is at its peak.

Although this tactic has proved successful for centuries, scientists now worry that the whales' adaptation is being outpaced by climate change. Over the past few decades, warming ocean temperatures and the changing patterns of sea ice have disrupted the krill bloom schedule. Unless these changes keep up their present rate, humpback whales could find it more and more difficult to synchronize migration with the availability of food.

"We have no idea how long they can continue to keep up," Millien cautioned. "Each year since 2016 has been the hottest on record, and that trend is accelerating. Eventually, their memory-based approach will not be effective anymore."

The research also discovered significant differences in the migration patterns between male and female humpback whales. Males migrate faster and use more direct routes to the feeding areas, whereas females, particularly those with calves, migrate longer coastal routes. Scientists are of the view that this is perhaps aimed at safeguarding the calves from predators and enabling them to rest along the way.

These discoveries underscore the urgent necessity for conservation efforts to safeguard the whales' migration corridors and feeding grounds. As ship traffic along coastal waters increases, humpback whales are increasingly vulnerable to collisions and habitat disruption. Hector Guzman, a study co-author and researcher at the Smithsonian Tropical Research Institute, has been involved in policy initiatives aimed at slowing down vessel speeds within critical whale habitats to counter these threats.

"This study gives the information required to guide conservation efforts," Guzman said. "It's not only about conserving whales; it's about conserving the fine balance of marine ecosystems."

The effect of climate change on the migration of whales highlights a wider crisis impacting sea life globally. With ocean temperatures increasing and ecosystems altering, those species that use seasonal cues to survive are greatly threatened. Humpback whales have a great reputation for adaptability, but whether they will be able to adapt fast enough to keep up with climate change is questionable.

Scientists say that conservation of migration routes and feeding grounds is essential to secure the long-term future of humpback whales. Though policy measures like lowering ship speeds in critical habitats may assist, mitigation of the main causes of climate change like greenhouse gas emissions and ocean warming must be tackled.

The results of the study provide a grim reminder that the interconnected nature of ocean ecosystems means that shifts in one place can have far-reaching implications all around the world. If krill numbers continue to fall or change in an unpredictable fashion, it could have drastic implications not only for humpback whales but for other marine life that has this essential food source to feed upon.

For now, researchers will continue monitoring whale migration patterns, hoping to better understand how these magnificent creatures are adapting to an increasingly unpredictable environment. Whether their memory-based migration strategy can withstand the rapid pace of climate change remains an open question—one that could determine the future of the species.