Bowhead whales have changed their migration patterns

Deep in the icy grip of the Arctic, a quiet revolution is underway. Creatures known as bowhead whales that have been swimming these waters for thousands of years have changed their migration patterns. This isn’t some whimsical detour; it’s a response to a world rapidly losing its ice to global warming.

Years of research from Oregon State University reveal how the whales bend and adapt, and also warn of big changes in the Arctic, impacting everything in the marine ecosystem.

Real-time tracking of bowhead whale migration

To understand why bowhead whales are changing their migration patterns, the researchers turned to a powerful tool: satellite tags. These tiny devices, attached to individual whales, allowed scientists to follow their journeys across the vast Arctic sea.

“Bowhead whales are highly vocal. Males sing pretty much twenty-four-seven from fall through spring, so you know when they’re there,” said Dr. Angela Szesciorka, a marine scientist at the Marine Mammal Institute who led the study.

The research team then compared modern whale movements with older records, revealing a clear shift over time.

Bowhead whales in the western Arctic have always followed the rhythm of the sea ice. When summer melts the ice, they head north to feeding grounds – and when winter brings ice back, they travel south. But the recent study has noticed a change in their routine.

These whales seem to be lingering longer in their summer feeding areas before starting their fall migration south. It’s like they’re enjoying the feast a little longer before facing the colder months.

Bowhead whales’ feeding strategy

Changing climate leads to longer Arctic summers. Melting ice allows sunlight to reach deeper, triggering a bloom of tiny ocean plants called phytoplankton. This feast attracts a swarm of zooplankton, small fish, and crustaceans, creating an underwater smorgasbord.

Among these revelers are the majestic bowhead whales. They linger for weeks, indulging in the summer bounty. But their feasting isn’t just about enjoyment; it’s a critical preparation for the harsh winter.

The fat reserves they build now become fuel for the long, dark months when food is scarce and temperatures plunge. The longer they feast, the better equipped they are to face the Arctic’s winter challenges. 

Changes in breeding patterns

Longer summers and ample food in the Arctic allow bowhead whales to feast and store fat, crucial for successful breeding. Well-fed whales are more likely to have healthy offsprings.

However, climate change throws a wrench in this cycle. Whales might delay their fall migration due to warmer waters, while shifting ice conditions disrupt breeding location and timing.

Bowhead whales usually choose specific, icy areas for mating, seeking protection from predators and harsh environments. Changing ice cover and warmer water could force them to breed elsewhere or at different times, potentially affecting their safety and calf survival.

Beyond these location issues, broader climate impacts pile on the stress: less food, more ships and exploration, and noisy oceans can all harm whale health and breeding behavior.

Dr. Szesciorka is concerned about a potential increase in ship collisions with bowhead whales. As whales shift north due to climate change and more ships travel in those areas, the risk of accidents goes up. “With this general northward shift paired with an increase in vessels and shipping, the threat of ship strikes will probably increase,” she said. 

Impact on the marine ecosystem

The Arctic Ocean is teeming with life, from tiny plankton to massive whales. All these creatures depend on each other to keep the ecosystem healthy. Bowhead whales, the giants of the Arctic, play a crucial role in this balance, and their movements have a big impact on everyone around them.

But what happens when their travels change? If their migration patterns change, where they eat and how much they eat changes too. This can affect the amount of food available for other animals, both big and small.

Moreover, when the big players, like bowhead whales, move around, the smaller ones have to adjust. If the whales leave their usual feeding grounds, the creatures they prey on might suddenly boom in numbers. This could be good news for some animals that eat those creatures, but bad news for others that depend on different food sources.

Implications of bowhead whale migration

All of these changes, big and small, add up. Bowhead whales are like pillars holding up the Arctic ecosystem. If they move around too much, the whole thing might start to wobble.

It’s a domino effect, where one change leads to another, throwing everything off balance. Not ideal for a healthy and happy ocean!

Bowhead whales, which were once considered a conservation success story, are changing their migration patterns due to climate change and human activities. 

“A shift like this may not necessarily be a bad thing for the whales, but any time we see more overlap with whales and shipping traffic, we should be concerned,” said Dr Szesciorka. “There will be winners and losers, but only time will tell.”

Messengers of ocean health

These whales are also like “messengers” of the ocean’s health, and their changing behavior suggests big changes in the Arctic ecosystem, which could affect food webs and the environment.

“We saw these changes in migration patterns in just nine years,” she said. “For a species that can live to 200, that’s pretty stark. That shows they can adapt to their changing environments for now. But will there be a point where they can’t adapt anymore? We have to wait and see,” said Dr. Szesciorka.

The study is published in the journal Geophysical Research Letters. 

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