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| The phenomenon of apparently healthy animals drifting to the coast to commit mass suicide has baffled scientists. Twitter pic |
January 12, 2016, NewsCrunch
The mass stranding of nearly 100 whales at Tuticorn has grabbed headlines. Fishermen and volunteers are battling valiantly to put them back to the sea.
But the animals are reportedly coming back to the beach to end their lives. The phenomenon of "mass stranding" - groups of distressed whales, dolphins and porpoises coming ashore alive - is poorly understood.
Here is what we know about the strange and tragic phenomenon.
1) Mass stranding has been documented for thousands of years, since Aristotle's times. The frequency is said to be increasing now and the blame is on human activity affecting the oceans.
3) The cetacean species, to which these animals belong, is extremely social. The bond that hold groups together are strong enough to supersede the survival instincts of individual animals. Whatever the cause of distress, they feel it collectively and move ashore together.
5) It has been observed that at certain times of the year, individual species seem to become more vulnerable to mass stranding - Pilot Whales(December), White-sided Dolphins (March), Common Dolphins(January), Risso's Dolphins (November) and Bottlenose Dolphins (December).
6) The biggest single whale stranding event known to science occurred in June 2015 at a remote fjord in southern Chile’s Patagonia. An observation flight discovered over 337 dead sei whales - 305 bodies and 32 skeletons. Scientists are analyzing the event for publication in a scientific journal.
7) In India the most stranding deaths occurred in 1973 when 147 whales got beached.
8) The stranding of individual whales is attributed to natural factors such as rough weather, old age or disease, difficulty in giving birth, hunting too close to shore, or navigation errors.
9) Mass strandings have been blamed on pollution, shipping noise, military sonar, earthquakes, geo-magnetic deviations, tidal currents gently-sloping coastlines and so on.
10) Science is now beginning to link active sonar to beaching. The low frequency active sonar used by the military to detect submarines is the loudest sound ever put into the seas.
There are documented incidents of whales stranding shortly after military sonar was active in the area. Necropsies of stranded animals have found internal injuries especially hemorrhaging.
In 2013, a US Navy funded study found that whales fled from loud sonar for the first time.
But the navies around the world are yet to accept the link and develop ways to mitigate sonar impact on these unfortunate animals.