Most of the surviving short-finned pilot whales stranded off a beach in western mainland Monroe County have moved and as of Thursday afternoon, scientists were "cautiously optimistic" the mammals could be traveling to deep enough waters to survive.
Around midday Thursday, U.S. Coast Guard patrols located three pods totaling 35 whales in about 12 feet of water and moving offshore near Seminole Pointe on Plover Key, said Blaire Mase, a stranding coordinator with NOAA's National Marine Fisheries Service. The area is about 10 miles north of where the original pod of about 51 whales was spotted Tuesday.
Later in the afternoon, the whales were about 6 miles offshore of Plover Key, traveling in a northwesterly direction, Mase said. Water there is about 18 feet deep, far from the depths short-finned pilot whales are used to inhabiting.
As of Thursday afternoon, 11 whales had died -- six were found dead by federal, state and volunteer marine mammal teams Wednesday morning. Veterinarians had to euthanize four others because their health was in such poor condition.
National Oceanic and Atmospheric Administration scientists and veterinarians, National Park Service rangers, Coast Guard crews and volunteers were unable to locate six of the whales that survived the initial stranding.
Wednesday, Mase said it seemed unlikely any of the whales would survive. The outlook improved Thursday, but Mase said anything could happen, including the whales turning around and beaching themselves again.
"The situation could go either way," Mase said during a press conference Thursday afternoon.
A similar situation played out in the mid-1990s, she said, when stranded whales last seen making their way out to sea ended up beached in the Keys days later.
Scientists are performing necropsies on the dead whales on location to get a better idea what caused them to die and what caused the pod to beach itself. One of the possibilities is the morbillivirus, which is killing marine mammals in the Mid-Atlantic and Southeastern Atlantic Ocean.
The whales were first spotted about 200 yards off Highland Beach, which is an extremely isolated section of western Everglades National Park. The surviving whales were swimming in as little 3 feet of water.
Happy endings are rare among pilot whale strandings, which are not unusual.
What makes saving them particularly difficult is the tight bonds they form -- they don't like to leave behind their dead and sick. This means that if people can heard the healthy whales and direct them back out to sea, the mammals often return when they realize some of their pod remained in the shallows.
Making the situation more dire for the survivors is their proximity to deep water, where short-finned pilot whales live. Highland Beach is about 20 miles east of the nearest deep drop off. In between lies an obstacle course of channels and sandbars the mammals must navigate.
The most recent mass whale stranding in the Keys was off Cudjoe Key in May 2011. In that instance, a pod of 23 pilot whales (actually large members of the dolphin family) stranded on the bayside.
Two adult males were healthy and released from the Lower Keys, but most soon died after the stranding.
Biologists don't know why whales strand.