Nobody likes noise – not us, not animals in forests and not fish in oceans. Loud and cacophonous noise displeases us, and, at times, even leads to dire health issues. But if that’s the case with us, do marine organisms feel the same way about noise? Does noise “displease” fish? Does it cause health issues in organisms that live in the seas?
Let’s look at the world through the lens of fishes. Light does not travel very far in water. So the vision of most fishes is limited to a few metres underwater. Luckily, fishes are very sensitive to sound. Unlike light, sound can travel across massive distances underwater. That’s why most of marine life depends on sound for navigation, reproduction, feeding, communication and even escaping predators.
And this where we step in. Our activities like commercial shipping, seismic surveys, military sonar and oil and gas exploration cause ocean noise pollution and permeate danger into the already dangerous and fragile lives of marine species. Navigation, reproduction, communication, escaping predators – these abilities of highly acoustic marine animals get damaged beyond repair. Fishes may even be forced to alter their migration routes or spawning sites to keep away from noise. Besides behavioral problems, marine organisms can face physiologic problems such as bleeding, hearing loss, tissue damage, or even death.
Plastic pollution, overfishing, trawling, etc. – these are known to impact oceanic environments adversely. But what remains lesser known is the effects of anthropogenic sounds on members of the marine world. And with noise levels rising precariously, the effects of ocean noise pollution cannot be overlooked.
In January 2016, more than 80 short-finned pilot whales were stranded on the shore in Thoothukudi, Tamil Nadu. In the same year, a 37-foot whale washed ashore in Mumbai. Incidents of stranding like these have been reported at various locations several times. While there is no one specific reason to explain them, it is understood that noise pollution might have a significant hand in their occurrences.
The fact that noise pollution levels in the Indian Ocean region have come down during the pandemic shines a glimmer of hope during these testing times. But this news should not in any way induce laxity in our measures.
Oceans are naturally noisy environments, with the survival of marine animals being largely dependent on sound. It is we who have intervened in these domains and broken the natural prosody of aquatic life.
While there is increasing awareness of certain perils to oceanic habitats, ocean noise pollution, though not a new phenomenon, needs greater awareness and scientific research.