Bigg's killer whale sightings continue upward trend in Salish Sea
One research scientist says the population is growing, but the whales are also leaving other areas
The Pacific Whale Watch Association (PWWA), which is made up of whale watching companies in B.C. and Washington state, says sightings of Bigg's killer whales in the Salish Sea are up significantly this year, continuing a trend that has been observed for several years.
The group says the sightings are consistent with an increase in Bigg's — also known as transient — killer whale populations in the area.
"This year is going to absolutely smash the record [for sightings]," said Erin Gless, executive director of the association.
"I would say 2016 is the first year that we started seeing the Bigg's more than the southern residents, and each year has been more and more and more since then," said Gless, adding that there was an anomaly in that trend during the COVID-19 pandemic in 2020, likely due to a lack of tours, sightings and data.
The Washington-based Orca Behavior Institute, which tracks sightings in the region, reported 214 unique Bigg's killer whales sightings in July, which was a 70 per cent increase from July 2023.
Different killer whales, different diets
The Bigg's killer whales are one of three ecologically distinct orca populations in B.C. waters. The other two are the southern resident killer whales and offshore killer whales.
According to Lance Barrett-Lennard, a research scientist with the Raincoast Conservation Foundation, there are few sightings of the offshore population, which is believed to largely subsist on a diet of fish and sharks.
The endangered southern resident whales prey on fish, primarily chinook salmon. The Bigg's, meanwhile, have a diet of marine mammals.
Barrett-Lennard believes it's the mammals, namely harbour seals, that are attracting the Bigg's killer whales to the Salish Sea — meaning there are fewer in other areas, like the Central Coast where he does lots of his work.
"We're seeing this shift because this is a particularly good place for their prey right now," he said. "I see fewer harbour seals in [central parts of the B.C. coast] than I used to."
Though he attributes the increased Bigg's sightings in the Salish Sea to a distribution trend based on food supply, Barrett-Lennard said it's still generally a good news story.
He said when Michael Bigg, for whom the whales are named, surveyed the population in the 1970s, there were 50 individuals identified. Barrett-Lennard figures Bigg may have missed another 50, but still, since that time, the population frequenting B.C. waters has more than tripled.
According to the PWWA, there are now 380 individual Bigg's killer whales, while the southern residents number fewer than 75.
Barrett-Lennard says the health of the two populations is also in stark contrast, as seen in their appearance. He said unlike the Bigg's, the southern resident whales appear thin.
"Bigg's killer whales, when viewed particularly from above, are fat. They're rotund animals," he said. "A fat whale is generally a healthy whale and those whales are fat."
Barrett-Lennard suggests that in the coming years, the Bigg's killer whales may overshoot their food supply in the Salish Sea — at which point fewer will be seen in the area and the trend celebrated by the PWWA will end.
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