Special report on technology and the oceans

Humans are starting to use the sea more as farmers than as hunters, says Hal Hodson

In the summer of 1942, as America’s Pacific fleet was slugging it out at the battle of Midway, the USS Jasper, a coastal patrol boat, was floating 130 nautical miles (240km) off the west coast of Mexico, listening to the sea below. It was alive with sound: “Some fish grunt, others whistle or sing, and some just grind their teeth,” reads the ship’s log.

The Jasper did not just listen. She sang her own song to the sea—a song of sonar. Experimental equipment on board beamed chirrups of sound into the depths and listened for their return. When they came back, they gave those on board a shock. The Jasper‘s charts said she was in 3,600 metres (2,000 fathoms) of water. But the time it took the soundwaves to bounce back said the bottom of the ocean was just 450 metres below the ship’s hull.

The instruments were not wrong. The interpretation was. The Jasper’s crew had found a new ecosystem so dense with aquatic life it appeared to their rudimentary sonar to be solid—a “phantom bottom” to the ocean. Unlike the sea’s true floor, it moved, its billions of inhabitants rising en masse to feed at night, then sinking away from predators during the day. This “deep scattering layer”—named for the way it was found by the scattering of sound waves—is not local to Mexico. Present in all the oceans, it is one of the largest ecosystems in the world. Its daily rise and fall is their heartbeat, an unseen spectacle of planetary extent.

That such a mass of animals should go undiscovered for so long shows quite how inscrutable the sea has always been. The subsurface ocean is inhospitable to humans and their machines. Salt water corrodes exposed mechanisms and absorbs both visible light and radio waves—thus ruling out radar and long-distance communication. The lack of breathable oxygen severely curtails human visits. The brutal pressure makes its depths hard to access at all.

The discovery of the deep scattering layer was a landmark in the use of technology to get around these problems. It was also a by-blow. The Jasper was not out there looking for deepwater plankton; it was working out how to use sonar (which stands for Sound Navigation And Ranging) to spot submarines, and thus help to keep ships like those at Midway safe.

Sonar research has been mostly military ever since, as have various other forms of high-tech ocean sensing. But the new sensorium allowed an exploration of the ocean’s depths that became crucial to science and commerce. Sea-floor surveys undertaken in the 1950s and 1960s discovered a chain of underwater mountains snaking through the oceans like the seam on a baseball. This discovery helped transform the controversial notion of continental drift into the far more powerful and explanatory theory of plate tectonics. Modern industrial fishing and offshore oil and gas benefited in similar ways: seeing the seas and their contents mattered.

In the past decade, remote underwater observation has moved to a new level as sonar technology has become more advanced. Computers have become powerful enough to turn the apparent gibberish that is created by numerous sound sources at various frequencies into high-resolution “sound pictures” of underwater objects. And smaller, cheaper electronic components using less power—a gift from the smartphone boom which kickstarted progress in drones, robotics and small satellites—are now putting to sea. They may be just as transformative there as in the skies and in space.

Darling it’s better down where it’s wetter

All this change promises to bring about a transformation in the way humans interact with the oceans. For most of history, people have had a hunter-gatherer relationship with the seas. That approach no longer works. If overfishing continues at the current rate, the seas will run out of fish. One response to this would be to decry the technological change that has made such overfishing possible. Another is to ask how the latest technology can be used in ways that improve things, undoing the damage of the past and making the old hunting ground a new realm, one that is more productive and more sustainable.

One crucial change brought about by the new technology is a reduction in the number of people involved. Until recently, using sonar was an expensive business, requiring a ship with a crew, towing equipment through the depths behind it. Now underwater drones (such as the one being launched in the picture on the previous page) can move around as fast as ocean currents flow, which means they can go wherever they want and stay there if needed. They can communicate acoustically, with each other or with a mother ship. Their lithium-ion batteries—one of those technologies smartphones have greatly improved—can provide power for days.

By removing the expense of keeping humans alive on or under the sea, these technologies vastly expand the volume of the ocean which can be monitored and measured, whether it be for fishery management or weather prediction. They enable the better study of icebergs, underwater volcanoes and every living creature under the sea. And drones will soon be able to transfer data on all of this instantly back to shore from the middle of the ocean, over newly built internet infrastructure.

“When data start to inform decisions, very interesting things happen,” says Bilal Zuberi, a partner at Lux, a venture-capital firm. These things include investment in infrastructure. Mr Zuberi envisions herds of wind turbines moving around the seas autonomously, grazing on winds which offer the most power. The possibility of mining previously inaccessible seabeds may become a reality. So may the farming of fish in the open ocean. As befits their origins, the new technologies have military implications, too, as improved undersea surveillance makes it harder for submarines to hide, thus denting their second-strike capabilities.