Killer whales are making their way into Hudson Bay in ever-increasing numbers. That’s bad news for the species that call the bay home.
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In January 2013, residents of Inukjuak, an Inuit settlement in Arctic Quebec, were met with an unusual sight: a dozen or so killer whales trapped by sea ice covering the waters of Hudson Bay. For two panicked days, the whales — once seen only rarely in the bay — took turns breathing through a modest hole in the ice.
Luckily, the ice eventually opened up and the whales were able to escape, although it is not known if they were able to make it to more friendly waters before encountering further ice cover.
Either way, their presence offered proof of a trend: the number of killer whales following prey into Hudson Bay is increasing as sea ice cover diminishes, melting earlier in the year and forming later. The trend is strong enough that one researcher — Steve Ferguson of Fisheries and Oceans Canada and the University of Manitoba — goes as far as to suggest that killer whales may eventually replace polar bears at the apex of the region’s food chain.
“They are there to eat,” Ferguson told CBC in a recent interview. “They appear to be eating other whales and seals. I would imagine, if we lose our sea ice, they will replace polar bears as the top predator.”
Not surprisingly, climate change is the driving force behind the expansion of the killer whales’ range. According to a database of
whaling logs and Inuit testimony compiled a few years ago by Ferguson and his colleague Jeff Higdon, the first reported sighting of a killer whale in Hudson Bay was in 1940. The whales remained almost unknown until the 1960s, when a flurry of seven sightings were recorded late in the decade.
That total grew to 84 in the 2000s. There were a further 24 between 2010 and 2014. And the trend shows no signs of slowing. This past June, two killer whale carcasses washed up on the shores of the Belcher Islands, just off the eastern coast of Hudson Bay. “Killer whales are not normally seen around the islands,” Lucassie Arragutainaq, head of the local hunters and trappers association, told CBC in an interview at the time. “But since winter to spring, several sightings have been reported.”
The growth in the number of sightings corresponds to an 11 per cent decrease in sea ice cover in Hudson Bay — equivalent to 16,000 square kilometres— between 1968 and 2010, according to federal government records.
In media interviews, Ferguson has said the growing presence of killer whales will significantly affect other species in the bay. Beluga whales, which are prey for killer whales, are of special concern. More than 55,000—about one-third of the world’s population—concentrate in river estuaries on the western coast each summer to mate, raise young and feed, providing a massive opportunity for predation.
Beyond Hudson Bay, sightings of killer whales are rising in parts of the Arctic. Inuit hunters report the whales have been seen targeting species such as narwhal and bowhead whales, in addition to beluga, in areas such as Foxe Basin and Lancaster Sound, between Hudson Bay and Devon Island.
Once these species had little to fear from killer whales, which avoid ice because it can damage their dorsal fins. The decline of their protective cover due to climate change, however, is altering their habitat. And that will almost certainly lead to change in the Hudson Bay ecosystem.