Story highlights 20 formerly stranded pilot whales ares spotted in deeper waters

Scientists worry the whales might be exhausted and dehydrated

Crews remain on standby for necropsies and rescues of more stranded whales

The struggle between life and death is not going so well for dozens of pilot whales stranded in shallow waters in Florida.

Rescuers have been trying to save about 30 whales by herding them into deeper waters.

Of the 51 whales originally stranded, 11 have died and five gone missing in the shallow waters on the edge of Everglades National Park, NOAA Fisheries officials said.

Scientists spotted 20 whales Friday afternoon about five nautical miles off shore.

The pod was moving in a southward direction and inshore, the National Oceanic and Atmospheric Administration said.

Photos: Photos: Whales stranded in Everglades Photos: Photos: Whales stranded in Everglades Whales stranded in Everglades – Officials in boats monitor dozens of pilot whales that are stranded in shallow water in a remote area of Florida's Everglades National Park, on Wednesday, December 4. Hide Caption 1 of 6 Photos: Photos: Whales stranded in Everglades Whales stranded in Everglades – A dead pilot whale lies near the beach in a remote area of Florida's Everglades National Park. Federal officials say 10 of the dozens of whales stranded are now dead. Hide Caption 2 of 6 Photos: Photos: Whales stranded in Everglades Whales stranded in Everglades – A dead pilot whale lies near the beach in a remote area of Everglades National Park. Hide Caption 3 of 6 Photos: Photos: Whales stranded in Everglades Whales stranded in Everglades – Officials monitor the scene where dozens of pilot whales are stranded in shallow water. Hide Caption 4 of 6 Photos: Photos: Whales stranded in Everglades Whales stranded in Everglades – A man paddles a kayak past two pilot whales in a remote area of Everglades National Park. Hide Caption 5 of 6 Photos: Photos: Whales stranded in Everglades Whales stranded in Everglades – Pilot whales are stranded on a beach in a remote area of the western portion of Everglades National Park on Tuesday, December, 3. The marine mammals are known to normally inhabit deep water. Hide Caption 6 of 6

"The whales were reportedly swimming more slowly and in a more disorganized fashion, which may suggest exhaustion, dehydration or malnutrition," marine scientists said.

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NOAA Fisheries is keeping crews on standby for necropsies and to rescue any live stranded whales.

Pilot whales are protected under the Marine Mammal Protection Act, but they are not endangered.

Mass strandings by pilot whales are not uncommon in Florida.

In 2012, nearly two dozen pilot whales stranded and beached themselves. In 2011, 23 pilot whales stranded and beached themselves.