When I initially learned of a whale stranding connected to an offshore seismic survey, I thought it sounded almost too good to be true. Undoubtedly a coincidence. Then, year after year, coastline after coastline, the same pattern continued to emerge. In February, as seismic surveys were being conducted in the same waters off Greece, another unusual stranding had place.
It makes sense that scientists are cautious in what they say about these topics. However, reading the literature gives the impression that there is less space for coincidences.
| Key Information | Details |
|---|---|
| Topic | Anthropogenic underwater noise pollution |
| Primary Sources | Shipping, seismic surveys, naval sonar, deep-sea mining |
| Marine Species Affected | Around 150 documented, from krill to blue whales |
| Noise Growth Rate | Doubled every decade since the 1960s in some regions |
| EU Waters Trend | Doubled between 2014 and 2019 |
| Loudest Source | Air guns in oil and gas surveys, up to 260 decibels |
| Key Researcher | Lindy Weilgart, marine biologist, Dalhousie University |
| Advocacy Body | OceanCare, Switzerland |
| Recent Stranding Event | February, atypical whale stranding off Greece during seismic surveys |
| Possible Quick Fix | A 10% global shipping speed reduction cuts noise by 40% |
One type of pollution that is impossible to capture on camera is underwater noise. No plastic island, no oil slick, and no dead bird with bottle tops in its gut. It may have taken so long for the public to take it seriously because it is invisible. For decades, oceanographers have been raising their hands. In certain regions of the world, man-made noise has doubled every ten years since the 1960s. According to a research from the European Maritime Safety Agency, it increased in just five years in European seas between 2014 and 2019. It’s not a gradual drift. It’s an acceleration.
The largest factor is shipping, which is something that most of us never consider. The South China Sea alone handles around one-third of all maritime traffic worldwide. Cavitating propellers on container ships, tankers, and bulk carriers all continuously emit low-frequency sound into the water column.
A longtime advocate for this cause, Lindy Weilgart, a marine biologist at Dalhousie University in Canada, notes that almost 150 marine species have been shown to be impacted—basically every species that has been investigated for it. The final detail is the one that sticks out. We are not discovering immune species. There aren’t many species left to test.
The air cannons come next. They shoot impulses of up to 260 decibels every ten to fifteen seconds, often for weeks at a time, and are used in seismic surveys to map oil and gas resources beneath the seabed. For a creature that is as dependent on sound as humans are on sight, picture that rhythm, day and night. It has killed krill larvae. Around survey zones, fish capture rates plummet. Additionally, something that didn’t exist a century ago drowns out the discussions of whales, who use low frequencies to communicate over thousands of kilometers.
Recently, a research in the Qiongzhou Strait, a tiny passage between Hainan Island and the Chinese mainland, attempted to quantify the severity of this in crowded maritime lanes. In three of the four trials conducted in 2018 and 2019, researchers discovered that the strait’s noise levels were higher than those known to temporarily impair the hearing of very-high-frequency cetaceans, such as the Indo-Pacific finless porpoise. Long believed to be a natural migration route, the strait may suddenly serve as something more like to a wall. The whistles of the dolphin populations on either side already differ from one another, just as languages vary between remote settlements.
The fact that some aspects of this story can be resolved sets it apart from prior environmental disasters. Reduce undersea noise by forty percent and slow the world’s shipping fleet by ten percent. It’s not a moonshot. It’s a policy meeting. Since deep-sea mining is still in its early stages of regulation, it might be put on hold before it starts to produce constant noise for decades. It is possible to modify naval sonar protocols. Developing new technology is not necessary for any of this.
It’s difficult to ignore how infrequently any of this appears on the home page. According to Nicolas Entrup of OceanCare, marine species are unable to escape the water. They inhabit the cacophony. As the science mounts, you begin to believe that the one thing we consistently refuse to offer them is the quiet we owe them.
