Pacific gray whales spotted in Puget Sound

File photo of Pacific gray whales in the Sound near Everett

A group of Pacific gray whales known as the Sounders because they stop over in Puget Sound during their coastal migration is beginning to arrive in the region.

As of Wednesday, at least four had been seen in the area, where scientists with the nonprofit Cascadia Research Collective have found they tend to congregate in waters off Whidbey Island and feed on ghost shrimp, the Skagit Valley Herald reported.

The first sighting was noted Feb. 3, according to the nonprofit Orca Network that records public sightings of whales throughout the region. By last week, multiple observers reported seeing two whales at once. As of Wednesday, Cascadia Research had identified at least four whales.

"We’ve confirmed at least four individuals and we expect that to be changing on an almost daily basis, now that we’re in March," said John Calambokidis, the organization’s senior researcher.

RELATED: Study: Southern resident orcas turn to other fish when Chinook salmon is scarce

Thousands of gray whales annually migrate from Mexico to Alaska, about 250 of them stop to spend time in the Salish Sea, and about a dozen of those are the Sounders that make their way to areas around Whidbey Island.

With the arrival of the whales, scientists are continuing long-term monitoring of the Sounders, and conducting new and ongoing research.

Stay connected with Q13 News on all platforms:

DOWNLOAD: Q13 News and Weather Apps
WATCH: Q13 News Live 
SUBSCRIBE: Q13 FOX on YouTube
FOLLOW: Facebook | Twitter | Instagram

"We have an expanded research effort this year," said Calambokidis, who has been studying this group of whales since 1990. Calambokidis has been looking into what draws the Sounders to the area: ghost shrimp burrowed in the intertidal Snohomish River delta.

"They predominantly, though not exclusively, feed off the bottom and will suck up the upper layer of the sediment," he said of the whales. "At low tide you can actually see the pits they are digging there."