It is a sad fact that all our handy-dandy technological advances make sounds. Whether it’s worrying about your pre-teen’s hearing after wearing that iPod or opting for an apartment on a quiet residential street - we all make decisions about sound, often daily. But animals are less able to make such choices, since they neither control the noisy devices nor have total freedom over their movements. It becomes even more problematic for those animals that rely on sound for much of their behaviour - feeding, mating, and navigating.
Noise pollution is a major issue for whales and dolphins. Cetaceans live in a highly sensitive acoustic environment, as sound carries long distances in water. High frequency noises attenuate rapidly, but low pitches can travel thousands of kilometres. A wide variety of human activities create far-reaching low frequency sounds, including oil exploration, shipping, research, and military purposes.

Petroleum companies use seismic profiling equipment to detect oil and gas deposits under the seafloor. This process involves setting off loud arrays of airguns at intervals. Geological research relies on similar techniques, as well as sonar, to map the topography of the seafloor and underlying crustal layers. Fishing boats also use sonar to track fish schools. Ship engines generate intense sounds, with larger ships creating louder noise profiles. Sound carries in all directions in water, with the impact depending on the source’s decibel level (or loudness), frequency, and depth.

Cetacean species use sound for behaviour such as echolocation and communication, so they bear specialized structures to effectively detect noises. Beaked whales of the Family Ziphiidae appear particularly affected by human sources of noise pollution, with stranding and mortality events linked to specific noises. Part of the problem is that even lower sound levels may be implicated, making it challenging to predict cause and effect.

The impact on beaked whales may be compounded by their habits. About 25% of all cetaceans belong to this Family, but they prefer deep water and are less familiar to science. These whales live in small groups and do not move extensive distances, so they may be more susceptible to disruptions. Disturbances can cause changes to fish prey, as well as increased stress and behavioural changes in whales.

Clearly, attitudes toward the oceans need to shift. Despite its seemingly endless depths and teeming life, many human activities have surprisingly ramifying consequences. Ingenious solutions will be necessary if we wish to both explore the ocean and conserve its inhabitants.