The Humpback Whales' Songs Are Alive Again

When feeding, fish exposed to noise catch fewer prey, are less efficient, and find it harder to discriminate between good and bad food. Fish in noisy places have higher levels of stress hormones, and the development of their hearing suffers. In some species, mortality rates double from the combined effects of these changes. The negative effects of noise even penetrate the ocean sediments. A study of burrowing clams, shrimp, and brittle stars showed that they change their behaviors in noisy conditions, reducing their movement and feeding. These changes to seemingly obscure creatures in ocean mud have consequences that ramify throughout the ecosystem. If this study represents a general finding, the noisiness of our oceans may leave its impression even in the stone that is left behind from our era, discernible to future geologists as a changed chemical signature in mud and rock, alongside the plastics, pollutants, and acidity that we have cast into the waves. The whales had swum north and circled back toward the island, their retinue following at a distance. We saw no more close approaches, but we gazed on their harlequin backs and flukes as the whales dallied at the surface. Returned to shore, I feel wobbly on the unmoving asphalt. In a few hours, my muscles and inner ears came to know and expect the motions of water. When I feel steady enough, I get in the car and turn on the ignition.

Heal The World

Gasoline squirts into pistons. It was likely barged here through the Puget Sound. Tree latex and fossil oil in my tires whirl over the road, flaking rubbery dust onto the impervious surface, a silt destined to wash to the sea. Back at a hotel, I plug my laptop, imported from across the Pacific via ship, into the wall socket. I lie down on a mattress permeated with flame retardant. Gentle knocking sounds. A crab moving around the kelp? A high whine, like an electric motor, runs for two minutes, then cuts off. A few outboard engines pass, atonal whirs. Through the night, the sound threads in and out of my sleep, waking me into confusion before dawn with the burr and slash of propellers gunning a boat through the water. The acoustic devilry that we daily stream into the subsurface world can be stopped. Unlike chemical pollution that lingers sometimes for centuries, or plastics that will persist for millennia, or the death of the coral reefs that will not be reversed for millions of years, sound pollution can be shut off in an instant. Silence from humans is unlikely, though.

A Hole In The World

Whether or not we are aware of our dependence on the sea, we are a maritime species. The energy and materials that supply our bodies and economies move largely by ship. Most of our oil, gas, and food travels among continents by sea. There is little chance, therefore, that the noise will cease entirely. But quieter oceans are within reach. It is possible to build almost silent ships. Navies have been doing so for decades. Some submarines are so stealthy that their presence can only be revealed by pumping into the water sonar loud enough to deafen any passing dolphin. Fisheries researchers seeking to measure fish abundance and behaviors do so from vessels with engines, gears, and propellers engineered to reduce noise and thus not alarm fish. The hush from these ships comes at the cost of efficiency and speed. Yet even for large commercial vessels, noise can be greatly reduced through careful design. Regular propeller repair and polishing reduce the formation of cavitation bubbles that are the main source of noise.

Breaking The Code Of Silence

Further reductions come from changing how engines are mounted, adjusting the shape of propeller blades, modifying propeller caps, sculpting the flow of wakes, adjusting how propellers interact with rudders, and operating propellers so that they spin at rates that reduce cavitation. Slowing the vessel, even by 10 or 20 percent, also cuts noise, sometimes by up to half. Many of these changes save fuel, giving a direct benefit to the ship operators, although not always enough to offset the costs of expensive reengineering. Quieting this clamorous minority could significantly reduce noise. But without a reduction in the volume of traffic, quieter ships might lead to more ship strikes if whales cannot hear approaching danger. For millions of years whales have safely traveled and rested at the water surface. Now blows from hulls and slashes from propellers are significant risks for whales in ocean shipping lanes and around busy ports. Technological tweaks have unintended consequences, especially if the movement of goods around the world continues to grow. As with shipping noise, reducing the overall number of ships conducting exercises would have the most significant effect. Even seismic surveys can be hushed. Were we to wean ourselves from the black milk of Earth, we would have little need to rake the oceans with sonic death rays. Failing that, other methods now exist to map the subsurface. This vibroseis technology is regularly used on land but has yet to be widely adopted in the ocean. Marine vibroseis produces sounds that overlap with animal senses and communicative signals but does so over smaller areas and in a narrower frequency range. These changes are mostly now only experimental, hypothetical, or enacted in small corners of the oceans. Regulation of marine noise happens piecemeal by country, with no binding international standards or goals. The noise in the oceans continues to worsen. A review in 2013 found that expenditures on seismic surveys were increasing at nearly 20 percent per year, more than ten billion dollars annually, capping two decades of rapid growth. These commodities all serve the global economy and are transported by ship. The impoverishment of sonic diversity on land and water, then, is part of the same crisis. We would also directly sense the human and ecological costs of our actions, a stronger foundation for wise ethical discernment. Such a reformation of the economy would not resolve the many problems we create, but it would better position us to find solutions and answers. We possess the technology and economic mechanisms needed to reduce our noise. The humpback whales’ songs are alive again in my headphones. I try to imagine where these animals are now.