Bowhead whales that washed up in Nunavut in 2020 were likely killed by orcas

Killer whales were likely responsible for the deaths of 11 bowhead whales found washed up in 2020 by the Gulf of Boothia in central Nunavut.

"We never know for sure how they died, but it does seem like a lot of the evidence points to killer whale predation," Steve Ferguson, a research scientist with Fisheries and Oceans Canada, said Thursday in his submission to the Nunavut Wildlife Management Board meeting in Iqaluit.

Hunters supplied tissue samples from eight whales, which his department used to investigate potential causes and extent of mortalities, Ferguson said.

The investigation looked at possible causes for the deaths including starvation, unusual weather events, harmful algal blooms and infectious diseases.

The sample analyses found a "contributing factor in the strandings may have been an interaction between poor body (nutritional) condition and predisposition to predation."

Most of the whales were young, Ferguson said. Results from their investigation showed that six out of eight sampled whales were under 20 years old.

Analyses of the blubber samples of the beached whales found no difference between their blubber and that sampled from hunted whales.

"We don't think contaminants were a problem," said Ferguson, noting the whales are still safe to eat.

In 2020, ice formation was late, he said, which could have contributed to the presence of orcas, also known as killer whales.

His department now plans to do modelling to get a better idea of the bowhead whale population size and its health.

Meanwhile, reports continue to surface about the vicious behaviour of killer whales outside the Arctic.

A recent paper published in the Marine Mammal Science journal detailed how killer whales have killed and eaten blue whales in three separate attacks off the coast of Australia since 2019.

At the end of one of those recorded hunts, a killer whale went into the mouth of the blue whale, probably to eat its tongue.

Before the Fisheries and Oceans Canada analyses of the Nunavut samples had been undertaken, Ferguson said injuries to the tongue of one of the beached bowhead whales appeared to resemble what had been observed before in orca kills, where an orca pulls down on the bowhead whale's lip to open the mouth, exposing the tongue to other killer whales.