Thousands Of Dead Fish Pile Up Along Mystic River Shores Near Everett, Somerville

SOMERVILLE (CBS) -- Thousands of dead fish have piled up along the shores of the Mystic River in Everett and Somerville.

SkyEye captured the floating fish in the river on Thursday afternoon.

Patrick Herron, Executive Director of the Mystic River Watershed Association, told WBZ-TV that the fish are Atlantic Medhaden. They were likely driven to the Mystic River by a predator.

Herron added that the deaths were natural, and they don't have anything to do with water quality.

"About a week ago, we noticed a large school of Atlantic Medhaden had come into the river. And that can be a sign of something very positive, a reminder that this river is alive," Herron said.

"And it can be a little alarming when they come in in such great densities, because as a schooling fish, they can use up all of the oxygen and die," he said. "And that's ultimately what happened."

Herron speculates that it could take up to a week for the fish to be removed from the area.

"The best thing for us to do is to hold our nose if you will, wait a little bit and the tides will carry it out," Herron said.