VICTORIA -- Humpback whales are making a significant comeback in the waters around Vancouver Island and northern Washington state, according to researchers at the Pacific Whale Watch Association.

Calling it a “humpback comeback,” researchers at the agency say the number of humpbacks in the Salish Sea has increased exponentially since a single whale was spotted in the region over 20 years ago.

“Since whale researchers first documented a single humpback whale in 1997, the humpback whales that migrate each summer to feed in the nutrient-rich waters of the Salish Sea now number in the hundreds,” the whale watch association said in a statement Tuesday.

The researchers say 2021 is proving no different, with the documented return of famed whale “Big Mama” and three of her calves.

The whale watch association says Big Mama is a “pioneer and significant contributor to this population increase,” giving birth to six calves that have returned to the inland waters of B.C. since 2003.

“When Big Mama arrived in late April 2021, the whale watch community was extremely excited to see her return, as she often marks the beginning of the humpback whale watching season throughout the region,” the association said. “Dozens more humpbacks have arrived since then, and this past week, something happened that had the whale watch and research community abuzz.”

The buzz arose when Big Mama was reportedly spotted on Saturday, feeding alongside three of her calves in the Strait of Juan de Fuca, south of Victoria.

“Humpback whales are not known to have close family ties, leaving their mothers at less than a year old,” the Pacific Whale Watch Association said. “The fact that three siblings were seen in such close proximity to each other has piqued the interest of humpback whale researchers.”

Big Mama was sighted for the first time in 1997 by a skipper with Prince of Whales Whale Watching near Race Rocks, southwest of Victoria. According to researchers, she was the first humpback spotted in the strait in nearly a century.

Since then, more than 500 humpbacks have been documented and cataloged in the Salish Sea, according to the Pacific Whale Watch Association.