People have long been watching the tragic death of whales and dolphins on the shore. Aristotle, who was the first to describe the habits and peculiarities of cetaceans more than 2300 years ago, mentioned the sad propensity of whales to kill themselves. In Historia Animalium, Aristotle wrote: "It is not known why they are thrown on land. In any case, it is known that they sometimes do it, and without much apparent reason. Once on the shore, the whale dies slowly and painfully under the weight of its own body. Why are the whales being thrown ashore? This happens too often to be considered an accident. There are several hypotheses about this.
1. Weakness or injury.
A whale, being ill or injured, loses the ability to fight the current and finds himself on the shore. This explanation looks logical and prosaic. Dead and dying marine animals are often found on the shore with damage caused by ships, fishing nets, and predators at sea. The same hypothesis also includes the natural old age of whales. It is interesting that whales as such do not become decrepit. But as they age, their senses become weaker and they break against underwater rocks, become broke or become prey to sharks and killer whales. The whale's ability to reproduce is a life-long one. The Greenlandic whale is the longest-lived warm-blooded animal. Their age, judging by the harpoons extracted from their bodies, can reach 200 years.
2. Periodic changes in the environment.
While scientists at the University of Tasmania have analyzed data collected over 82 years of monitoring on the shores of Tasmania and Australia and noted that whales are released ashore more frequently every 11-13 years, coinciding with changes in wind speed. Perhaps a change in wind speeds up plankton and small fish to the shore, luring whales too close to the shore. It is also possible that the changed wind changes the wave in the ocean, which in turn disorients the whales, and they are too close to the shore. Once in shallow water, the whales quickly become tired and die. Ocean tides are also dangerous for whales and dolphins. Only gray California whales can easily tolerate drying out at low tide.
3. Sociality of whales
Strong social ties within the herd can be the reason why whales are being thrown ashore in large numbers. If one whale is caught in shallow water and unable to get out, he starts to emit a distress signal, his relatives are trying to help him and are also stranded. Disease and weakening of the whale - the leader can destroy the herd. According to one theory, the whales still have a deep instinct from their ancestors: they are afraid of drowning. A weakened whale swims up, closer to the air, and the rest of the herd follows. Whales are characterized by mutual assistance, a well-known fact that dolphins save drowning people. But it is the same quality that ruins them.
4. Exposure of people.
Although submarines and sonars are relatively new, it is difficult to avoid their environmental impacts, particularly on whales. On the shores of the UK, the number of cetaceans released has increased by 25% in 20 years. Ecologists and scientists attribute this to the use of powerful military sonar. Whales have a subtle hearing, and the loud sound of sonar frightens them, makes them rise rapidly to the surface or go to depth, disorienting them. But this is not the worst, too fast surfacing from great depth to the surface may threaten the known to divers caisson (decompression) disease. It causes gas bubbles to form in the blood from a rapid change in pressure. The examination of whale bodies confirms the presence of gas bubbles in the blood.
In the middle of the 20th century, US Navy ships actively conducted exercises in the Caribbean and Mediterranean seas. It was found that cetaceans were indeed more likely to be grounded when naval ships worked on their sonar operations there. Exercises in beaked whale habitats are now prohibited. In 2000, 17 cetaceans of 4 different species were released to the shores of the Bahamas following sonar exercises in the area.
5. Geomagnetic navigation error.
Many migrating animals use geomagnetic navigation, including whales. The whale humpback whale is able to travel 2000 km without stopping, not losing course by more than 1 degree. In total, humpbacks travel about 6500 km for migration. And yet for reasons not fully studied the navigation of animals sometimes gives failure. It is most likely that some electromagnetic forces interfere with the correct operation of the whale navigation system, for example, magnetic storms on the Sun, as it is known, sometimes lead a flock of migratory birds astray. So in 2015 a flock of pink flamingos somehow arrived in Siberia. In addition, artificial sources of magnetic waves, such as radar and possibly even body and radio signals, can significantly affect the biocompass of marine animals. This may explain why rescued whales are often thrown ashore again in the same place almost immediately after they are rescued.
These are the most scientifically proven reasons why whales are released ashore. Fortunately, people no longer consider the defenseless on the shores of sea giants to be easy prey, as they did in the past centuries, but on the contrary, they try to bring the whales back to sea as soon as possible. And there is hope that in the future when scientists find the answer to the question of why whales are being thrown ashore, people will be able to predict or even prevent further mass mortality of whales.