Ecocentric

Beach Mystery: Why Did Dozens of Whales Strand Themselves in the Everglades?

As rescuers try to save dozens of whales stranded in the Florida Everglades, the question of why such beachings occur remains unclear

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Reuters

A National Park Service volunteer looks at a dead pilot whale on a beach in Florida's Everglades on Dec. 4, 2013. The whales were part of a group of about 50 that were in danger of being stranded in the shallow water of the Everglades earlier in the week; 10 of them later died

Wildlife officials, scientists and volunteers have been scrambling this week to save dozens of pilot whales that beached themselves in the shallow waters of Florida’s Everglades. A fishing guide on Dec. 3 discovered a pod of 51 whales in a remote area of the Everglades called Highland Beach, more than 20 miles away from water deep enough to support them. When officials from the National Oceanic and Atmospheric Administration (NOAA) Fisheries department responded to the call the next morning, they found six of the pilot whales already dead and were forced to euthanize four more.

The effort then began to try to herd the remaining pilot whales out to the open sea, where they’d be able to find food and survive. (Beached whales eventually die slowly from starvation and dehydration, which is why wildlife officials will euthanize them as a last resort.) The chances of success were not high — past whale strandings in the same area had led to mass deaths, and in general, it can be difficult to coax whales from shallow water back to the open sea. This is especially true for highly social animals like the pilot whale, which travel in close-knit family groups, known as pods. Pilot whales are loath to abandon family members, even if it puts the entire group at risk.

But it’s possible that the Everglades beaching may have a happy ending. On Dec. 4, though rescuers found another whale dead, they were surprised to discover that some 35 of the whales had begun to move themselves into deeper water. But even when whales move offshore, they can restrand. In a Friday morning update on Twitter, NOAA officials said that they had been unable to locate a larger group of 24 whales, though a handful of individual whales were seen free-swimming in deeper water, and weather had made it harder to spot the whales from air. (It doesn’t help that sharks have begun to feed on the bodies of the dead whales, creating a danger for rescuers on the water.) Still, the fact that the whales can’t be spotted could be good news — it’s possible that they’ve made it out to open sea. But it’s impossible to know yet for sure.

(MORE: Scientists Optimistic That Stranded Whales in Florida Will Survive)

The question remains, though: Why would such a large group of whales put themselves in such danger? Some of the pilot whales may have been sick — the whales are known to carry the morbillivirus, a highly contagious disease that can cause respiratory problems and weakness in affected marine mammals. The virus spread in the mid-Atlantic this summer, with some 800 dolphins falling victim. It’s possible that a handful of the pilot whales could have gotten sick and disoriented, and inadvertently led the rest of the pod into trouble — though scientists won’t know until they’ve had a chance to perform necropsies on the dead whales, which will take weeks.

Still, scientists don’t really understand why whales seem to choose to beach themselves, refusing to save themselves even though it means their death. Strandings may be natural — there are reports of whale and dolphin beachings going back to the time of the ancient Greeks — but human activity also seems to be a factor. (Though not, contrary to popular belief, military sonar — a 2009 study found that sonar waves were likely too quiet to disorient whales or dolphins.) Nan Rice, of the Dolphin Action & Protection Group, gave this explanation to Scientific American a few years ago:

I often use the analogy of a car crash, because a lot of things can go wrong but you get the same result. Statistically, we are only able to determine the cause of a stranding in about 50 percent of all cases worldwide. In some cases it is obvious, like a ship strike leaving an animal in poor condition. In the northeastern United States pneumonia is a common cause of stranding. We see other diseases and trauma, such as shark attack on whales or dolphins or attacks by members of the same species. Poisonous “red tides” will also affect marine mammals. Some strandings have been speculated to be related to anomalies in the magnetic field.

Down in Florida, boats and helicopters from the National Park Service and the U.S. Coast Guard are still out searching for the missing whales. And if we’re lucky, they’re already in the open ocean, on their way home.

MORE: Adoption at Sea: Sperm Whales Take In Outcast Bottlenose Dolphin

4 comments
Nazonohito
Nazonohito

According the the principles of Occam's razor, the simplest explanation is probably the best one... So, I have concluded that the whales must have been using Apple Maps to navigate.

dwms07
dwms07

Brian, since mass strandings have been going on for millions of years, the most logical explanation would be that a pod of beached whales previously lost their ability to echonavigate due to some sort of catastrophic event of nature. They are blind to what's in front of them. A cochlea injury could disable their biosonar, and, since whales use the air in their sinuses as acoustic mirrors, barosinusitis would also cause them to lose all sense of direction. But what million-year-old catastrophe could possibly deafen a pod of whales or cause barotrauma in their sinuses?  An undersea volcanic explosion could knock out their cochleas. Piston-like movement in the seabed during certain undersea earthquakes could also generate a series of excessive and rapid low frequency changes in diving pressure that could blow out all their cranial air sacs and sinuses. Neither of these injuries would be visible; the whales would look healthy, but be unable to dive and feed themselves and echonavigate. Not feeding, they would soon become dehydrated and likely suffer immune dysfunction.  Sharks would sense they were in trouble and follow them like wolves dogging a herd of elk. But where would the whales go after such an injury knocked out their sense of direction? There is only one answer... their travel path would be directed by the flow of the surface currents. They would swim downstream in the path of least resistance. Anything and everything without a sense of direction always goes downstream with the flow.  And, since surface currents that are directing the whales is the same energy that carries each grain of sand to build beaches, the injured pod would likely end their journey on a beach. They have no reverse gear so they can't swim backward. There they lay until some human comes along and pushes them back out to the waiting sharks, hogging the TV cameras calming they save the poor stranded whales. Ha! At least the sharks are getting fed.