Well, we just reported that in New Zealand, about 200 more black grind dolphins stranded on land near Cape Fairwell in the north of the South Island. All TV channels show how volunteers are trying to save them, pouring water on them and wrapping them in wet rags.
At the same time, about 400 grinds were thrown in the same area the day before. Most of them, up to 300 individuals, were reportedly already dead.
Such cases are not the first in history. Why is this happening?
People have found marine animals that, for some unknown reason, were thrown ashore, at least since the first century AD - this is evidenced by ancient Roman and ancient Greek documents. Today, marine biologists undertake to name only half of these incidents, and the reasons are very different.
In 2002, 55 whales were stranded on the coast of Cape Cod Bay. Thanks to the efforts of American rescuers, 46 animals were saved. People poured water on the whales and covered them with wet towels, preventing them from overheating. When the tide started, the whales were dragged into the water. Alas, some of these sea animals never saw the tide.
In 2004, 15 whales were stranded on the shores of the two islands in the Canary Archipelago. Only three of them were saved.
In June 2005, about 160 whales were stranded off the coast of Australia. Rescuers with the help of volunteers did not let the five-meter "fish" die.
Promotional video:
In October 2005, 70 whales died on the beaches of the island of Tasmania (Australia).
In March 2007, 12 whales stranded on the coast of one of the Galapagos Islands. Despite all the efforts of the rescuers, seven animals died.
In 2012, in Cape Cod alone, 177 dolphins ran aground and 124 died, according to reports from the Associated Press. The report also mentioned that in total this number of dolphins exceeds the average of 37 animals, which was recorded in the previous 12 years.
More than 200 dead dolphins have been dumped on the beaches of Chiclayo, Peru. In this case, they found not only dead dolphins, but also dead fish - anchovies. Since this small fish is food for dolphins, it is possible that they became ill because of these fish, but the cause of death of the animals remains a mystery.
Why is this happening ?
This is often an injury or illness. An animal that has been attacked by a predator may feel too weak to stay on the water, at some point it gives up and allows the waves to carry itself ashore. In our case, Konstantin Zgurovsky, the head of the WWF's marine program, suggested that cetaceans could have been stunned by seismic surveys or underwater acoustic systems on warships. According to the expert, there are also suggestions of infection of animals with worms or poisoning by pollutants that enter the ocean, such as heavy metals.
Climate cycles could change the direction of movement of fish and other living things that dolphins feed on. Dolphins, in pursuit of prey, could swim close to the coast and be thrown onto land. This makes sense when you consider that sardines and other fish that have washed ashore in Peru have been found with dolphins.
Cases when a whole group of animals are thrown ashore are much more mysterious. One of the explanations that scientists offer is that whales and dolphins that hunt and migrate in small herds are victims of their own social structure. If the leader or dominant animal is washed ashore due to illness or injury, then the rest of the group can follow him. Whales always help out a relative from their flock. If one of the whales wanders into shallow water by mistake, it immediately starts giving signals to its congeners, and they rush to help. Alas, whales, instead of rescuing a comrade, themselves get into trouble.
Another version is that the herd swims too close to the shore and does not have time to return at low tide.
In some cases, sea animals commit massive "suicides" soon after the active use of nearby military sonars. In 2000, in the Bahamas, for example, 17 animals of four different species (beaked whales, toothed whales, minke whales and spotted dolphins) were found on the shore in 36 hours - on the day the sonar was used in these places and on the following days.
Research carried out by the National Oceanic and Atmospheric Administration since the incident has shown that naval echolocation devices were the most likely cause. Research data suggests that sonars influenced both the physical condition and behavior of marine animals.
Whales are great at navigating the ocean, which is why biologists say they have a magnetic compass in their brains, allowing these marine life to navigate the earth's magnetic field. If a geomagnetic obstacle occurs in front of the whales, their internal compass breaks down and they begin to swim the wrong way. It is known that rescued whales are often washed ashore again. Perhaps this is precisely due to the breakdown of the compass - the whales returned to the water, but they cannot find their bearings.
There is also a theory of noise. This theory is the most popular today. Scientists say whales and dolphins are being killed by the deafening hum of submarines. Loss of hearing, the whales lose their bearings and are thrown ashore. Examination of the bodies of escaped animals suggested that decompression sickness (decompression sickness) was the cause of the suicide. This malaise occurs when there is a sharp decrease in external pressure. Caisson disease is called a disease of divers, pilots and workers working in caissons (underwater working chambers).
The strong noise under the water scares the whales, and they begin to climb too quickly - there is a sharp decrease in external pressure. This is what provokes the onset of decompression sickness in whales. Echo sounders, radars, sonars, missiles, submarines can scare whales. This version is supported by the facts - there are several examples that the release of whales occurred at the time of military exercises using sonar.
It also happens that animals are thrown ashore on purpose - for hunting. Killer whales, for example, often attack pinnipeds, such as seals or sea lions, in the surf zone or near the very shore, where their victims change their way of movement from swimming to walking and do it quite awkwardly. While the animal tries to get out of the water, the killer whale makes a dash and grabs its prey. After that, she can either wait for a suitable wave, or try to return to the ocean, wriggling with her whole body.
Here is video evidence of one such hunt:
Be that as it may, scientists have not yet come to a consensus.
