There was a rare mass sighting of orca whales early Monday afternoon off South Whidbey, said Howard Garrett of Orca Network, the local whale-tracking organization based in Greenbank.

He said 29 of the 85 “neighborhood whales” local researchers have been monitoring since 1986 were spotted off Scatchet Head about 1 p.m. on July 13.

The group continued into Possession Sound, then north up Admiralty Inlet, and by the next day they were spotted where the whales were supposed to be this time of year, around the San Juan Islands, Garrett said Friday.

“It’s a virtually unheard-of visit,” Garrett said. “You expect them around here in the fall and into January, but not in July.”

He said the whales were probably foraging for chinook and chum salmon, but noted it was unlikely that they found many.

The whales were first spotted on Monday morning by the crew of the Victoria Clipper passenger vessel, Garrett said.

“It reminds us to keep our eye out at all times of the year,” he said.

To report a sighting, call the Orca Network at 360-678-6768.