Cetacean stranding, known as beaching, is a phenomenon in which dolphins and whales strand themselves on land. Beached whales die due to collapsing under their weight, dehydration, or drowning when the tide covers their blowhole. As many as 300 dolphins and whales strand each year. While most stranding is of individual animals, mass strandings are common and can involve hundreds of animals at a time.
On November 2, Sri Lanka’s navy, coastguard, and several local volunteers rescued 120 short-finned pilot whales stranded in the country’s biggest mass beaching ever. At least two injured whales were found dead.
The school of pilot whales had washed ashore at Panadura, 15 miles (25km) south of Sri Lanka’s capital Colombo. The rescue team had finally pulled back all the whales by dawn the next day, after an exhausting overnight mission. “We used our small inshore patrol craft to pull the whales one by one back into deeper waters. Sadly, two whales had died of the injuries sustained when they beached,” said navy spokesman Indika de Silva.
The Marine Environment Protection Authority (MEPA) of Sri Lanka confirmed that the Panadura incident was the country’s most massive single pod of whales stranded. “It is very unusual for such a large number to reach our shores,” said MEPA chief Dharshani Lahandapura.
Short-finned pilot whales, which can grow 6 meters (20 feet) long and weigh a ton, are incredibly social animals. Researchers don’t know the exact cause of mass strandings even though they’ve studied the phenomenon for decades.
However, there are a few suspicions about why the cetaceans strand, including they get old, sick, or injured. Navigational errors can occur when they’re chasing prey or running from predators. The strong social bonding of some whale species, such as the pilot whales, can cause mass strandings. Whales that mass strand are typically deep-water species that have highly evolved social structures.
A typical pattern with mass strandings is one or two whales will initially strand, and their strong social bonds draw in the rest of the pod. The whales will send out distress signals, and members from their pod may come to help, and at that moment, a receding tide catches these animals out, and soon the entire school will become stranded onshore.
