It was a record-breaking year for orca and humpback whale sightings in the Salish Sea last year, according to a whale-watching operator in B.C. and Washington.

The year-end data put together by the Pacific Whale Watch Association (PWWA) and local researchers showed more Bigg's killer and humpback whales visited the waters surrounding the southern tip of Vancouver Island, and into Washington, than ever before. They also reported a baby boom that experts are hoping will maintain the whale population.

"It was just a really great year as far as sightings go. Whales, basically every single day," said Erin Gless, the director of PWWA.

"We've got the Bigg's killer whales and we've also got the humpback whales, and both of them are just exploding off the charts."

There were 1,067 unique sightings of Bigg's killer whales last year — up from the previous record set in 2019 of 747. They were also seen across 329 days of the year, or just over 90 per cent of 2021.

Humpback whales were seen 301 days of the year.

Gless says a sighting is classified as the observation of one particular group of whales throughout a given day.

"It's not just one person calling in a sighting about a group of whales and then another person from across the way calling in the same one," she said.

"When we're talking about more than a thousand sightings, you're talking about more than a thousand different groups of whales throughout the year. So really, really phenomenal."

Last year also saw the birth of 11 baby Bigg's killer whales and 21 humpback whale calves.

What seems to be bringing the whales to the region is the abundance of food, according to Monika Wieland Shields, the director of the Orca Behavior Institute.

"Word seems to be spreading about how great the Salish Sea is, if you're a Bigg's killer whale," she said.

"There's a lot for them to feast on here. We have abundant harbour seals and sea lions, harbour porpoise and those make up the majority of their diet. And so we've seen this steady increase over the last 10 years of how much they're utilizing the area. And it just seems like more whales are spending more time here each year and taking advantage of that abundant food source."

Gless said since the hunting of marine mammals such as seals and sea lions was banned in the 1970s, the population has recovered, attracting predators like the Bigg's killer whales back to the region.

But Wieland Shields says it's a different story for the endangered Southern Resident whales — the other principal killer whale found in the region — as their sightings dropped to a record low last year. The salmon-eating mammals were documented on just 103 days, or 28 per cent of the year.

"The rise of the Bigg's killer whale … and the return of humpback whales to the region are all really positive stories that reflect a healthy and recovering ecosystem," she said.

"But at the same time, the decline of the Southern Residents reflects the decline of some of the salmon runs in the area and a part of the ecosystem that's not doing as well. So we really have these two different stories playing out simultaneously here."

However, the return of Bigg's killer whales and humpback whales may be good news for the Southern Residents, said Wieland Shields, as they could help control the seal and sea lion populations.

"Seals and sea lions eat a lot of different things, but they do eat salmon. And in some areas, they may be a contributing factor to some salmon runs that are struggling to recover," she said.

"There may be a food web effect there, where the Bigg's killer whales helping control the seal and sea lion populations actually help salmon ultimately recover for the Southern Residents."