The Pacific Whale Watch Association (PWWA), an umbrella organization for whale watching companies in British Columbia and Washington state, said the number of Bigg’s killer whale sightings in the Salish Sea has increased significantly this year, continuing a trend that has been observed for several years.
The group says the observations are consistent with an increase in the population of Bigg’s killer whales, also known as transient killer whales, in the area.
“This year will completely break the record [for sightings]“said Erin Gless, executive director of the association.
“I would say 2016 was the first year we started seeing more Biggs than Southerners, and every year since then it’s been more and more,” Gless said, adding that 2020 saw an anomaly in the trend during the COVID-19 pandemic, likely due to a lack of trips, sightings and data.
The Washington-based Orca Behavior Institute, which monitors sightings in the region, recorded 214 unique sightings of Bigg’s killer whales in July, a 70 percent increase compared to July 2023.
Different Orcs, Different Diets
Bigg’s killer whales are one of three ecologically distinct populations of killer whales in British Columbian waters. The other two are the southern killer whales and the offshore killer whales.
According to Lance Barrett-Lennard, a scientist at the Raincoast Conservation Foundation, the offshore population is rarely seen and is believed to feed mainly on fish and sharks.
Endangered southern resident whales prey on fish, primarily chinook salmon. Meanwhile, Bigg’s feed on marine mammals.
Barrett-Lennard believes it’s mammals, specifically harbor seals, that attract Bigg’s killer whales to the Salish Sea — which means there are fewer of them in other areas, like the Central Coast where he does much of his work.
“We see this change because it is a particularly good place for their prey right now,” he said. “I see fewer harbor seals in [central parts of the B.C. coast] than before.”
A group of five Bigg’s killer whales belonging to pod T049A were spotted on Tuesday, April 23. Migratory killer whales feed on marine mammals, unlike resident killer whales, which mainly feed on chinook salmon.
Barrett-Lennard attributes the increased number of Bigg sightings in the Salish Sea to a distribution trend based on food availability, but said overall it is good news.
He said that when Michael Bigg, for whom the whales are named, surveyed the population in the 1970s, 50 individuals were identified. Barrett-Lennard believes Bigg may have missed another 50, but that since then the population visiting British Columbian waters has more than tripled.
According to PWWA, there are currently 380 Bigg’s killer whales left in the world, while the southern population numbers less than 75 individuals.
Barrett-Lennard said the health of the two populations is also in stark contrast, and that’s evident from their appearance. He said that unlike Bigg, the southern resident whales appear thin.
“Bigg’s killer whales, especially when you look at them from above, are fat. They’re round animals,” he said. “A fat whale is generally a healthy whale, and these whales are fat.”
Barrett-Lennard suggests that in the coming years, Bigg’s killer whales could exhaust their food resources in the Salish Sea, in which case there would be fewer of them in the area and the trend promoted by PWWA would end.
