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Thursday, May 30, 2019

Sound and Sustainability among the Whales


         How is sound related to sustainability among whales, and how is whale sustainability related to the sound commons?
         By now most people have heard, or heard about, the songs of the humpback whales. Baleen whales such as the humpback and right whales “sing” to communicate their whereabouts in the ocean, just as birds do in the air and on land. That is, like many other animals and insects they use sound for a variety of purposes including giving warning, attracting mates, and keeping the social group together. Public interest in whale “song” focuses on two other aspects of whale song: whether these utterances are signals like alarm bells or if they make up a language; and whether they offer any kind of aesthetic experience to whales, as music does to humans. While those are very interesting questions, there is not enough reliable evidence to answer them; whereas there is good evidence for their use as functional signals.
        When other sounds interfere with the sounds animals make, it becomes hard for animals to communicate with each other. When sound interference is frequent, or even constant, the habitat becomes unforgiving and animals cannot survive in it very well if at all. They must either adapt, as birds raise the pitch range of their songs in the presence of vehicular traffic noise, or move into a different habitat. Shipping noise, from powerful engines and turbines, and from naval sonar, travels long distances through the ocean water—much farther than it would on land—and interferes with baleen whale sonic communication. It's not the only way whale sustainability is compromised by human activity; hunting whales, now banned by most but not all nations, and inadvertent entanglements in fish netting, are two prominent examples. More subtle, perhaps, is the effect of shipping noise; but it is no less harmful for that. Shipping noise also interferes with sound communication among toothed whales, such as orcas (killer whales), that use sonic echolocation in hunting for their prey.  
Orca (killer whale), courtesy Wikimedia Commons
    Orcas, for example, emit sound signals that bounce back from fish such as salmon. When an orca locates its prey it continues to give off these signals, the sound indicating where and how close the prey is as the orca closes in on it. Shipping noise drastically limits the distance over which these signals can operate effectively. It causes orcas and other toothed whales to alter their migration routes but it may also confuse them and cause them stress, resulting in illness and unusual behavior resulting in death. The same is true of shipping noise and baleen whales.
Right whales are in the news where I live because lobster lines (ropes) are a hazard that entangles them and kills them; estimates indicate that only 450 of the North Atlantic Right Whale species still exist. Eliminating the lobster fishery in New England, a multimillion dollar business, would have a catastrophic impact on the economies of many coastal towns and surrounding areas that are overly dependent on lobster fishing. The fish and game management regulators that would limit the lobster catch must weigh the interests of the human populations versus the interests of biodiversity, ecosystem services and the survival of a whale species. There is no similar balance of interests when it comes to shipping noise, however. Ships traveling in known whale habitat are asked to slow down and limit their noise, while activists campaign, with some success, against the indiscriminate use of naval sonar exercises. 
        The sound commons, in this case the ocean, is a soundscape freely accessed and open to all with as little sound interference as possible. At certain times and places, on account of limited access, or competition among those who would access it, the soundscape must be managed. Sometimes this can be done chiefly or entirely by those who do access it. Many medieval agricultural commons were managed in this way. The soundscape of one’s own living quarters usually is managed this way, as family members agree to limit each other’s access. But sometimes self-management fails, and outside management is the only possible solution. Noise ordinances are one example, but these are not always effective and they may also be unjust. Usually the best management involves input both from the outside experts and those who compete for access to the sound commons. In the case of whales, of course, their input is implicit rather than explicit. Yet they occupy a sound commons, and humans would be wise to manage it for everyone’s benefit, rather than damaging it in exchange for short-term human economic gains. In the end, damaging the biodiversity of the Planet compromises human survival as well.