MARATHON, Fla. -- In the race against time to help save a large group of stranded dolphins, many have already been moved back out to sea, but at least five have died.

PICTURES: Rescuers Struggle To Save Stranded Dolphins

The estimated number of dolphins stranded off Marathon Key was as high as 96. As of late Thursday afternoon, 36 remained in a pen, at least 20 are still beached, five have died, and 20 have been moved back out to sea.

A group of veterinarians, members of marine mammal rescue groups and volunteers are caring for the wayward rough-tooth dolphins that stranded themselves just off Marathon Key Wednesday afternoon. The animals became stranded on a sandbar and a shallow area about 100 yards offshore. Rough-tooth dolphins are not a coastal species. They are typically found in deep, offshore waters in the Gulf of Mexico and the Atlantic Ocean.

"This particular species, they are a highly social animal. And so there could be one or two animals that are sick and the other animals follow them in, but then they suffer the secondary effects of the stranding, which is dehydrations, hypothermia," said rescue coordinator Blair Nase.

Wildlife officials took to the air Thursday morning, hovering offshore in a helicopter to get a better look at how many dolphins were involved. Rescuers began marking dolphins on their dorsal fins with red tags as a way to keep track of them.

Video

VIDEO: Fight For Survival

Some of the dolphins are doing better than others. Those animals were herded into a deep-water, dead-end canal where they can swim and stay hydrated. Boats brought most of the dolphins to the canal, though one hitched a ride on a stretcher in the back of a pickup truck, said Denise Jackson, a member of the Marine Mammal Rescue Team.

For now the animals will remain penned in the area because rescuers are afraid they could end up stranded in a shallow area between the canal and deeper ocean waters.

Police had to herd hundreds of onlookers away from the canal. Officials were afraid that a dock overlooking the waterway might collapse, so police set up a barrier to keep people off it.

Rescuers' Plan

Veterinarians are conducting blood tests and other medical assessments on the dolphins.

As the day goes on, they want to separate the animals into the following three groups:

Healthy dolphins that can be released
Sick dolphins that can be rehabilitated
Very sick dolphins that will have to be euthanized

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