(CNN) About 26 whales beached this week in Georgia -- and 16 of them died -- in the second mass stranding this year in the state, the Georgia Department of Natural Resources said.

The short-finned pilot whales were stranded Wednesday on or near St. Catherines Island south of Savannah, the department said in a news release.

Pilot whales at the Georgia shore this week

It's unknown why whales beach themselves. This species is the most common to mass-strand in the southeastern US, the DNR said.

Necropsies (animal autopsies) are being performed on the carcasses to try to determine why the whales ended up on the beach.

Whales are highly social and travel in pods.

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