Orcas? Overheating? Enough Food Already On Site? Bowhead Whales Did Not Migrate In 2018-19
As the ice melts at pace in the Arctic, the mining and shipping industry has carved itself an opportunity out of the crisis. Meanwhile, the marine ecosystem is left to coping with the heat, noise, pollution and the cascade of other changes that come with the upheaval of the environment. Now researchers have found a whale species that typically migrates away from solid sea ice each autumn and returns every summer to feast on tiny crustaceans did not make the 6,000km (3,700-mile) roundtrip in 2018-2019.
Bowhead whales are one of the few species that reside almost exclusively in Arctic and subarctic waters, thriving within a narrow temperature preference window, generally between ?0.5C (32.9F) and 2C. There are now four different stocks of these whales swimming along in the Arctic — one of the biggest stocks migrate annually from the northern Bering Sea, through the Chukchi Sea in the spring, to the Beaufort Sea where they spend much of the summer before returning again to the Bering Sea in the autumn to weather out the winter.
Using data extracted from underwater tape recorders, researchers in Canada concluded that this whale population did not make their annual journey in 2018-2019, they wrote in the journal Royal Society Open Science. Lead author Dr Stephen Insley from Wildlife Conservation Society Canada said it was unclear whether this change was an aberration or the beginning of a new way of life.
The researchers have suggested a plethora of potential factors that could explain what occurred. As water temperatures rise, the proliferation of predators such as killer whales (orcas) could have influenced the bowheads to stay put over winter. One potential factor is that given bowhead blubber can be up to half a meter thick, extra warmth could put the whales at risk of overheating. It could also be that there was an abundance of food such as plankton driven by higher temperatures – and so the whales may have elected to save their energy and bulk up by forgoing the travel.
EDIT
https://www.theguardian.com/environment/2021/apr/21/melting-ice-in-arctic-linked-to-bowhead-whales-holding-off-annual-migration
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