Beaching of Whales on Tamil Nadu Coast

In the second week of January 2016, around 80 short-finned whales had beached near Mandapu village in Tutucorin district of Tamil Nadu. Of them more than 40 whales were dead and the remaining whales were rescued in a joint operation by several government agencies and fishermen, and whales were pushed back to sea. The dead whales were buried near the shore at Tuticorin. Marine scientists say that the short-finned whales are deep water whales. Full details about this particular group of whales are not known. The IUCN Red List of Threatened Species classifies it as ‘data deficient’.

Why Whales are special?

Whales are large aquatic mammals. They live fully in water and breathe air through blowholes into lungs. Their sleek, streamline bodies allow them to move easily through the water. Studies on captive whales show they let only one side of their brain sleep at a time, while the other works to keep the animal swimming and surfacing for air. They are warm-blooded. Whales are intelligent and live cultural lives. They are two types of whales. The toothed whales use their peg-like teeth to catch fish, squid, and marine mammals, swallowing them whole. The baleen whales use the filter-feeder system to trap quantities of plankton and other small prey.

How do whales move in sea waters?

Toothed whales use echolocation to sense objects. In echolocation, whales send out high-pitched sound. The sound bounces off the object and returns to whale. Whale’s brain process the echo to find the location, size, shape and texture of the object. Baleen whales do not have an echolocation capability. They migrate over huge distances without deviations. But it is still unclear how they find their way in vast oceans.

Why whales get beached?

The exact reason is not known. The stranding phenomenon found with toothed whales. Whales act strangely when they become weak, contracted with a disease, when their migration routes are get disturbed because of ecosystem invasion or for any other reason. Once they faced with any disturbance, the whales which moves in groups get disoriented and eventually ends up getting stranded onshore only to die.

Natural causes:

• An earthquake causes the whales to get disoriented.
• Whales strand when they contract with disease, or weak, they let the waves take control of them.

Human made causes:

• Collision of ships,
• Pollution of the ocean waters,
• Changes in temperature of ocean waters from industrial releases,
• Sound of ships and use of sonar devices in the Ocean, and
• Injuries from fishing nets.

Is it the first time happened?

Whale stranding is neither a recent phenomenon nor uncommon. While dead whales would naturally washed ashore, mass beaching has baffled humans since at least 300 BC. Major short-finned pilot whale stranding episodes reported in 1852 in Kolkata and in 1973 when 147 whales were stranded on the beach in Tamil Nadu.

What could be the reason for whale beaching in Tutucorin?

The reason for Tutucorin incident could be while in search of food, an entire group followed a disoriented leader into shallow waters and beach themselves. The other reasons could be due to climate change, pollution of waters, an undersea earthquake, and hearing loss due to high levels of man-made noise from shipping activity. Gently-sloping shorelines can deceive whales dependent on echolocation for navigation. The Manapad beach is flatter.

What is the impact of SONAR?

Active SONAR release low frequency sound in under water to detect marine vehicles. It is the human version of the echolocation technology. The SONAR waves can cause internal bleeding in the ear and brain tissues, killing or disorienting whales. Sometimes whales may interpret SONAR as an approaching predator, triggering panic and subsequent beaching.