Noise pollution, how DSM could influence whale communication?

By Maya Crute Jones
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Imagine trying to have an important conversation amidst drilling, hammering and high-pitched pings that hurt your ears. This has become the 24/7 norm for whales and dolphins (cetaceans) in a seascape that is far from natural. 

Cetaceans are highly social mammals that rely on their ability to emit and receive sound for just about everything. Even before the industrial revolution, the ocean was not as Jacques Cousteau described it, “a silent world”. The ocean is a cacophony of noise used for communication, socialising and predator/prey interactions. Odontocetes (cetaceans with teeth such as dolphins and Orcas) communicate through clicks and whistles and echolocate to find their prey. The deepest diving cetacean ever recorded was the Cuvier’s Beaked whale who dove to 3000m to hunt giant squid after receiving signals of their presence. 

Mysticetes (whales with plates of baleen such as Blue and Humpback whales) make wide bandwidth calls to communicate literally across oceans. The beautiful male Humpback whale song was included in a disc sent into the far reaches of space for an alien race to show the sentience of our water world.  

Whales are able to communicate over entire oceans due to the ability of noise to be propagated much further and faster in water than it does through air. In offshore industries there are strict regulations on when piling for wind turbines, using seismic air guns to find oil and detonating mines from WW2, can occur. These regulations are in accordance with marine mammal breeding, migrations and feeding seasons. Mitigation zones are set up around noise producing activities to reduce harm to marine mammals if their ability to interpret sound is “masked”. This is because cetaceans have exhibited behavioural, feeding and mating changes and man-made noise has been linked to mass cetacean death by stranding.

The International Seabed Authority’s exploration licences currently place no temporal or spatial limits to noise creation. Even if they did, effective monitoring, control and enforcement will be extremely difficult in these areas beyond national jurisdiction. For deep-sea mining, sound will not only be produced on the seafloor but throughout the entire water column from the surface to the abyss. Noise pollution would be emitted by the main vessel, pumps, thrusters, geophysical and undersea communications. Riser systems bringing the mined metals from the seafloor to the surface all emit noise and there is no data or knowledge about them in the public domain. It has been calculated that for 17 proposed deep-sea mines, the size of the acoustic footprint could be 5.5 million km2, roughly the size of Australia EACH. 

For such sentient and social beings, this would be devastating for cetaceans. Not only will cetaceans avoid the area but so will their prey, as fish and invertebrates are also sensitive to anthropogenic noise. This could spell disaster for species that are already suffering from their prey being exploited in illegal overfishing on the high seas. With the constant threat of entanglement, pollution and hunting, we have the power to stop yet another dire threat to cetaceans before it starts!

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