Little Ray & Shark Patch Things Up
April 2018 by V. R. Duin

UNNATURAL OCEAN SOUNDS

Right-side up, then upside down,
Little Ray loved to act the clown.
The young stingray showed off for friends,
Who cheered his leaps and flips and bends.
(“Little Ray & Shark Patch Things Up”)

Unnatural ocean sounds present a noise pollution threat for marine life.

Rolling tides and gentle waves are not the only ocean sounds heard in the sea. Water bodies are full of naturally occurring sounds that humans may be unable to hear. While unnatural sounds are loud and obvious, natural sounds may go unnoticed by humans. Natural ocean sounds are predictable. Fish do not have vocal boxes. However, they make use of water, air and their swim bladders to produce sounds. The resulting barks, bubbles, groans, grunts, hisses, hoots, moans, rattling sounds, tail and body thumps and some splashing noises should be audible to much of ocean life. Stingrays can make grunting sounds with air and water expulsion. Sharks use their teeth and jaws to make gnashing noises, and they can expel water in a bark-like sound. These sounds may indicate whether the animal is ready to play, fight or mate. Unfortunately, these natural sounds often are drowned out by the unnatural sounds produced by human activities and the noise of their machines.

Sounds may enable animals to compete for attention, space definition or submission. There may be a hierarchy of natural sounds regulating approach or withdrawal in the ocean. These basic vocalizations may have evolved into the advanced communicative organs in humans. Sounds made by several sea mammals are familiar to humans; seals, sea lions, walruses, dolphins and whales. Many people have heard dolphins and whales chirp, squeak, click and make whistling sounds through their blow holes. Because they are different, but related mammals, some dolphin sounds may not be possible for porpoises to make. Unlike dolphin and whale sounds, humans cannot hear porpoise sounds. Rays and sharks are considered silent hunters, but they can let out a burp when air is trapped in their stomachs while being reeled in during fishing. Do sharks make sounds? Animal senses are often stronger than those of humans.

Most fish can hear or sense all of the naturally occurring sounds of marine life and of the water in which they reside. Dolphins, porpoises and whales depend upon these ocean sounds to navigate, find food and communicate. The ocean is a moving and unsettled environment where sight and smell are not always useful, and touch may be dangerous. Unnatural sound presents a noise pollution threat, because it interferes with the useful sounds needed for the survival of many marine animals. Some fish and marine animals are territorial and protective of their space. Slow-moving ocean life may not be able or willing to get out of the way of the machines making these noises. As boat traffic increases, more of these animals are killed or seriously injured and stressed, placing them at greater risk to predators and disease.

Stingrays will flee from sound vibrations, such as those made by shuffling feet in the sand. Sharks are known to attack flapping sounds, as these may be indicative of weak prey. This does not mean that sharks are only drawn to dying or injured prey. Some shark species are very protective of their territory. Natural ocean sounds may cause some fish to flee and may draw aggressive species in for an attack. When whales slap their tales, fish may herd together for safety. This brings together many watchful eyes for the school. It also provides a confusing mass from which some predators cannot distinguish individual prey. With a whale, however, the whole school may get eaten as a group. Natural sounds are compatible with the natural life cycle of the sea. Sounds may help an animal bluff a predator into fleeing, rather than staying for the fight.

Whales and fish slap their tails against the water surface, plants and other objects. Tail thumping may be used to scare away predators, newcomers or to mark territory. It often is used in cooperative hunting. Team tail thumping drives prey to shallow water where it is easily caught. The sound of a tail thump is not as loud or as common as the vocal sounds made by sea animals. However, these sounds are natural and often result in stress reduction. In addition to a feeding technique, these noises may be used in spawning or mating activities. Tail thumping may be used for communications between a mother whale and her calf or to get attention. The enemy leaves, the tail thumper is triumphant and the offspring is delivered to safety.

It is the loud, unnatural ocean sounds that are stressful for marine life. These noise pollution threats include the recreational sounds of loud music, boat engines and depth sounding devices. Geophysical and oceanographic experiments create intense noise. Loud, unnatural ocean sounds cause physical and emotional stress and injury to marine life. The increasingly severe, increasingly common, extremely loud and totally unnatural sounds of military sonar blasts, oil drilling booms, industrial ship engines, air guns for seismic surveys, and explosives for undersea construction present serious underwater noise pollution threats to marine life.

Loud noises can affect the physiology and behavior of marine life. Some noises can seriously injure and ultimately kill marine life. For people and for animals, noise has been associated with disruptions of metabolic and immune systems. Loud noise causes stress, interferes with rest and impairs hearing. Chronic exposure to stress can damage blood vessels and the nervous system that regulates body functions. Unnatural sounds in the ocean are on the increase. Advanced sensing technologies and robotics are opening up new areas of the ocean to development.

To combat unnatural ocean sounds, NOAA is mapping a strategy for the reduction of these oceanic noise pollution threats to marine life. While interacting with the ocean, everyone should be aware of and attentive to reducing the effects of recreational and industrial sounds on marine life. The NOAA Ocean Noise Strategy Road Map is an ongoing collaborative effort. It was launched with public comment and feedback.

Pollution Threats

  • marine life admin says:

    Julia Purser, UK biologist, has authored or co-authored articles about injury, death and other effects of noise on marine life.

  • ocean sounds admin says:

    Governments are drafting regulations to reduce harmful, unnatural ocean sounds.

    • noise pollution threatadmin says:

      Offshore construction, with driving piles and explosives, worsens the noise pollution threat.