Forty-five pilot whales pushed back into the ocean after beaching themselves on Cape Cod on Monday have died. Most were put down by veterinarians after coming ashore again on beaches close by.
The whales were part of a pod of 55 that beached on Monday morning. This was one of the largest mass-strandings of pilot whales in the area in a decade.
But early on Tuesday, the 46 surviving animals beached again. This time, 31 were successfully re-floated, only to swim ashore again 40 kilometres from the first landing site on Tuesday afternoon. Six died before vets arrived and performed euthanasia the remaining 25.
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鈥淪adly, pilot whales are very prone to stranding,鈥� says Vanessa Williams of the UK-based Whale and Dolphin Conservation Society. 鈥淭hey are a very sociable species, and tend to stay together come what may.鈥�
Re-beaching 鈥渃ommon鈥�
The reason for the mass-stranding in Cape Cod is unclear. Whale researchers think pods will follow a sick or injured leader, even if it heads for shore. They may also beach after becoming disoriented, particularly if hunting in a shallow bay.
Re-beaching is quite common, says Williams. 鈥淚n some conditions they will re-float successfully, but sadly some or all will often come back in.鈥�
The biggest threats to beached whales are dehydration, overheating and the loss of water support, which can lead to their internal organs being crushed.
Mass-strandings are not unusual, Williams says. On Friday, 58 false killer whales were discovered by fishermen on a beach near Albany, Australia. Most of the whales had already died, and the rest were put down.
鈥淭here have been reports of several hundred whales beaching together,鈥� Williams adds. 鈥淎nd globally, on average, beached whales would number in the high hundreds if not the thousands each year.鈥�