Whales in hot water: Will climate change disrupt their migration?

Every year, humpback whales in the southeastern Pacific make a long and difficult journey. They travel up to 10,000 kilometers from Central and South America to their feeding grounds in Antarctica.

But how do they know when it’s time to leave? According to new research, these whales rely on both real-time changes in their environment and long-term memories of past ocean conditions to time their migrations.

The study, led by scientists from McGill University, used eight years of satellite tracking data collected between 2009 and 2016. The team tracked 42 humpback whales tagged near Costa Rica, Panama, and Ecuador.

By following the whales’ movements southward to Antarctica, the researchers hoped to understand what cues triggered their annual migration.

Whales use memory to time their journey

The study revealed that whales respond to local cues such as sea surface temperature and food availability.

But they don’t rely solely on current conditions. They also seem to remember when food was most abundant in the Southern Ocean during previous years.

That memory, combined with what’s happening around them, helps them decide when to go.

“They seem to know that changes happening in their immediate environment are linked to conditions thousands of kilometers away,” said Professor Virginie Millien. “This allows them to fine-tune their migration, so they arrive just as their food supply peaks.”

Krill, a small crustacean, is the whales’ main food source in Antarctica. Each year, krill populations bloom during a specific seasonal window.

For centuries, whales have timed their migration to match this pattern. But that rhythm is now being disrupted.

Can whales keep up with climate change?

Warmer oceans and changes in sea ice are beginning to shift the timing of the krill bloom. Even though whales are adjusting their departures, climate change may be moving too fast for them to keep up.

“We don’t know how long they’ll be able to keep up,” said Millien. “Every 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.”

The study also revealed notable differences in how males and females migrate. Male humpbacks tend to travel more quickly and take direct paths.

In contrast, females – especially those with calves – stick to the coast. Their route is slower but possibly safer, giving their young time to rest and stay away from predators.

Delicate balance of marine ecosystems

These findings have important implications for conservation. As ship traffic increases along coastal routes, so do the dangers whales face.

Collisions with vessels and disturbances to their migration corridors can have serious effects on whale populations.

“This research provides the data needed to inform conservation efforts,” said Hector Guzman of the Smithsonian Tropical Research Institute. “It’s not just about protecting whales; it’s about preserving the delicate balance of marine ecosystems.”

The researchers emphasize the need to safeguard migration routes and feeding zones, especially as the climate continues to shift. Protecting these areas doesn’t just benefit whales – it supports the entire marine food web.

Why whales matter more than ever

Whales are amazing animals that help keep oceans and seas healthy. As they move, whales consume food and excrete waste – assisting with the distribution of nutrients in the water body.

This enables the growth of phytoplankton and other microscopic plants which take in carbon dioxide and give out oxygen. Thus, whales make a direct contribution to the food webs of the ocean and the climate on land.

Their existence also boosts biodiversity, creating new feeding opportunities for other marine creatures that depend on nutrient-rich zones.

If whale populations are decimated, the productivity of the ocean will decline. As waters undergo more drastic changes, the survival of humpback whales is crucial.

Observations of humpback whales provide researchers with insights into the limits of ecosystem resilience and the measures needed to prevent collapse. From this perspective, protecting whales becomes a priority, along with assessing the overall health and stability of the oceans.

The full study was published in the journal Scientific Reports.

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