The Sorrow beneath the Sea

Article excerpt

Byline: Callum Roberts

Imagine an underwater world without whales, sharks, and dolphins, where jellyfish and algae rule. It's already happening.

Like children the world over, my daughters love turtles. At once incongruous and graceful, they connect us to the world of 15 million years ago, when very similar turtles swam alongside megatooth sharks, or 75 million years ago, when they rubbed shoulders with dinosaurs. Only eight species of marine turtle remain from a lineage that stretches back little changed deep into the age of dinosaurs. The largest living reptile is the leatherback turtle, a barnacle-encrusted eminence that can reach 10 feet long and weigh two tons. Today we confront the stark possibility that people will drive the leatherback turtle to extinction within the next human generation. Already there is just one leatherback left in the Pacific for every 20 in 1962, the year I was born.

Human dominion over nature has finally reached the sea.

With an ever-accelerating tide of human impact, the oceans have changed more in the last 30 years than in all of human history before. In most places, the seas have lost upwards of 75 percent of their megafauna--large animals such as whales, dolphins, sharks, rays, and turtles--as fishing and hunting spread in waves across the face of the planet. For some species, like whitetip sharks, American sawfish, or the once "common" skate, numbers are down as much as 99 percent. By the end of the 20th century, almost nowhere shallower than 3,000 feet remained untouched by commercial fishing. Some places are now fished down to 10,000 feet.

Why, in the face of widespread evidence of human impact, do so many people persist in thinking that the oceans remain wild and beyond our influence? The answer lies in part in the creeping rate of change. Younger generations are often dismissive of the tales of old-timers, rejecting their stories in favor of things they've experienced themselves. The result is a phenomenon known as "shifting baseline syndrome," as we take for granted things that would have seemed inconceivable two generations ago.

Loren McClenachan, a graduate at Scripps Institution of Oceanography, unearthed a telling example of shifting baselines in the archives of the Monroe County Library in Florida. She found a series of photographs of fish landed into Key West by one recreational fishing charter company between the 1950s and 1980s, and extended it by taking her own pictures at the same dock. In the 1950s, huge Goliath groupers and sharks dominated catches, many of them bigger and fatter than the anglers. Over the years, the fish shrink and groupers and sharks give way to smaller snappers and grunts, but the grins on the anglers' faces are just as broad today as they were in the 1950s. Modern-day tourists have no idea that anything has changed.

With the sole exception of Alaskan salmon, which have been well managed, and rockfish or striped bass, which have experienced a resurgence thanks to the careful shepherding of their fisheries, most of the species we like to eat have plummeted since their historic highs. Puget Sound's salmon runs have dwindled to a trickle. Red snapper, bluefish, and menhaden are all overfished in U.S. waters today, while grouper and capelin are far below their 19th-century numbers. In 2010, a quarter of commercial fish stocks assessed in the U.S. were considered overfished, meaning that they lie below target levels, themselves far below historic highs. But this misses the real scale of the problem. Overfishing is only one small piece in a much larger puzzle of interacting impacts.

We pump chemical and industrial pollutants into our rivers and oceans, heedless of consequences, and our unplanned experiment with greenhouse gases is gradually infiltrating the deep sea, changing ocean chemistry, impacting temperatures and oxygen levels, and shifting patterns of underwater currents with dramatic consequences. …