A news release issued by the group called the sightings "spectacular" and "an extraordinary conservation success story."
The humpback whale population of northern Washington state and southern British Columbia was destroyed by commercial whaling in earlier years, but whaling restrictions have enabled the big marine mammals to make a comeback here, says one expert.
"These sightings of humpback whales are really encouraging," said marine zoologist Anna Hall, science adviser to the Pacific Whale Watch Association. "Now they're not only back in these waters, they've actually expanded their temporal use. We're seeing them almost every day out there, sometimes doing spectacular things."
Whale-watching boats are seeing a wide range of feeding behaviors among the humpbacks, suggesting that the whales are successfully foraging for different types of local prey.
The huge whales have also been seen breaching completely out of the water before crashing back to the surface.
"We had up to five humpbacks here for about 10 days in May," reported Tom Averna of Deer Harbor Charters on Orcas Island. "And we're continuing to see them into June. I don't recall having humpbacks in the islands like this in the 25 years I've been running trips."
"The mothers seem to feel this is a safe place to take the calves," said Hall.
Olympia-based Cascadia Research Collective estimates that about 1,600 humpback whales feed off the West Coast, including as many as 500 off Washington and British Columbia.