How is noise pollution killing whales?

As we have slowly made our mark on the world and started to cultivate it to our liking and preferences, we have had a noticeable impact on the lives of many other species that share this world with us. We have sometimes even directly led to the extinction of a few species. And as our industrial footprint grows across the globe, so does the death toll of animals lost in this new and confusing world.

There are many reasons behind whales meeting their deaths on the shores. Sometimes they lose their way and move towards the beach. Some whales, swimming too close to the shores, are beached when there’s a steep decline in the water level during low tide. Whales are endowed with a natural “compass” in their heads. This compass, which works on the basis of the Earth’s magnetic field, helps them navigate through the sea. Unfortunately for the whales, the magnetic field is not the same everywhere. It is greater near the poles and weaker near the equator. It affects the whales’ built in compass which does not work perfectly in areas where the magnetic field is weak. Many a times a whale unknowingly approaches the sea shore due to a navigation error and if it is stranded on the land, there is a slim chance for its survival. Its body collapses under its own weight and soon it can die of dehydration.

While the whale navigates using its natural compass, it finds its way under the water using its natural sonar. The whale emits high-pitched sound waves in the water. These waves bounce back from the sea-bed (or other fish and objects) and upon receiving them the whale decodes its route. This way of finding directions is known as echolocation; and it works perfectly when the sea is calm.

Unfortunately, seas around the world are not as peaceful as they used to be a few decades ago. There has been a great increase in the level of noise pollution in the seas and oceans across the globe due to industrialization. Drilling of deep-sea oil wells creates a deafening sound under the water. Propellers of giant military as well as cargo ships, submarines, oil tankers etc. produce jarring sounds. Military submarines’ and ships’ sonar equipment transmits low-frequency sound to locate enemy ships or submarines. This sound is almost never less than 230 decibels — nearly twice the sound produced by the jet engine of a combat aircraft.

All these factors add to the ever-increasing levels of noise pollution in the sea. The sound waves emitted by the whale in order to map its route through the water therefore get scattered. The whale cannot receive them back. It loses its course due to lack of mapping, and sometimes swims towards shallow shores — only to meet a painful death. While about 360 whales died due to beaching in 1994, the figure rose to 782 in 2004, and 2,000 in the year 2010. This clearly indicates the increase of noise pollution by humans in the ocean. This also indicates the extent to which human interference with the environment can cause damage to the ecology.

Our noise in the oceans doesn’t just impact the echolocation used by whales however. It can even damage their hearing. And in some extreme cases, our noise is enough to cause internal bleeding amongst whales, which is almost always fatal. And painful. Our interruption of the communication between these creatures is enough to induce massive behavioral changes within them. And these often lead to whales doing unusual things, with them ending up beached and dead in the end run.