Updated

About 25 pilot whales have been founded dead off Florida's southwest coast.

National Oceanic and Atmospheric Administration fisheries official Blair Mase said the whales were spotted by boaters on Kice Island Thursday.

The whales were part of a pod of 23 first discovered swimming Sunday in Naples Bay. They were seen again Monday about 2 miles off Marco Island.

Eight other pilot whales died at Lover's Key near Fort Myers earlier in the week. Necropsies showed they all had empty stomachs. A cause of death has not been determined.

Pilot whales are susceptible to mass strandings because they tend to form close-knit social groups. However, Mase said there has been a higher number over the last year.

More than 50 pilot whales were stranded in the Everglades in December.