MIAMI Eight pilot whales died and dozens more were being monitored on Tuesday after the animals wandered into shallow waters off Florida's west coast, scientists said.
Four of the whales died naturally and four were euthanized after they left the deep waters of the Gulf of Mexico near Fort Myers, officials said. Boat traffic was stopped on some waterways in an effort to protect any animals that remained.
"These animals are showing signs of being underweight, being dehydrated, and they've likely been out of their home range," said Blair Mase, a regional marine stranding coordinator for the National Oceanic and Atmospheric Administration (NOAA). "We have no idea why they're in shore."
Wildlife officials also were watching a group of 23 whales that swam into shallow waters near Naples on Florida's southwest coast over the weekend.
Pilot whales can grow up to 20 feet long and a weight of nearly 7,000 pounds.
In early December, 51 pilot whales swam into shallow water in the Florida Keys, triggering a frantic rescue effort. At least 22 whales died.
Mase said tests showed those whales were not infected with the morbilivirus virus, a measles-like infection that was responsible for the deaths of more than 1,000 bottlenose dolphins last year.
NOAA officials said the recent groups of whales that swam in shore are different from those that were found in the Keys. Why the whales are venturing into shallow waters is unclear, scientists said.
"It could be environmental issues, could be disease," NOAA's Mase said. "We're looking at biotoxins as well."
Pilot whales are a social, deep-water species that live in pods of 20 to 90 whales and typically will not leave ailing or dead members behind. The animals forage on squid, octopus and fish, and cannot live long in shallow water.
(This story has been refiled to correct number of whales that died in December to 22 in sixth paragraph)
(Editing by Colleen Jenkins and Jonathan Oatis)