We’re Scraping Bottom

As vessels around the world drag nets and dredges across the seabed, they slowly destroy the biome

I was brought up to admire commercial fishermen, and I still do. The feeling took root during childhood summers in Gloucester, Massachusetts, when that city was still a premier fishing center. I would watch the boats pass Ten Pound Island and then the Eastern Point breakwater as they headed for the open sea, for Browns Bank or Georges Bank. I would watch them returning, and then read in the Gloucester Daily Times how many pounds of what kind of fish each boat had brought in. One of the high points of my early childhood was riding a boat from Gloucester to Boston and back, for ice. I can still remember sitting at lunch when the single-cylinder diesel engine missed just one beat. Every man at the table was on his feet before the engine resumed its steady chuff chuff chuff. Everyone sat down again and picked up the conversation where they had left off.

Some of the outbound traffic I watched towed boats in which nets called purse seines were stored. Their crews would use the boats to deploy the nets in circles around schools of mackerel and then pull in a line on the bottom of the net so it closed. Others were swordfishermen, their harpoons lashed to the bowsprit. Still others carried steel-framed dredges with chain bags to gather scallops. But most were what in the Northeast were called draggers: they would drag great bags of net across the bottom, then haul them up and dump the catch on deck (Smithsonian, May 1985). The bags are held open by floats fastened along the top, weights on the bottom and angled boards at the sides. The boards are called otter boards, and the whole rig is an otter trawl, the most widely used towed bottom-fishing gear.

These fishers are, on an industrial scale, the last hunters of wild things, men and women who go to sea to catch the finfish and shellfish the rest of us love. This is not weekend sailing on the bay. It is working on the open ocean in winter as well as summer, sometimes in weather that would keep "sensible" people indoors, not to mention off the water. It is using axes to chop frozen spray from wheelhouse and mast before the boat becomes top-heavy and rolls under. Later in life I bored my long-suffering children by pointing out to them the high bows and heavy construction of commercial fishing boats compared with the pleasure boats tied up in the same harbors. It's the difference between the Western and Eastern ways of riding horses, as explained to me once by a wrangler at a dude ranch. "Out here," he said, "we ride horses to get somewhere." Fishing boats are serious.

My admiration for commercial fishermen has not diminished by the proverbial iota. (In fact, I go through cycles of buying a monthly publication called The National Fisherman, written for them.) But I'm finally having to face a terrible truth, one a child could have figured out but that somehow does not seem possible in the vastness of ocean from one horizon to the next. Dragging those nets across the bottom, year after year and decade after decade, wrecks the bottom. Reality has come to face me. A couple of years ago I chanced to see on television a film of an otter trawl moving across the bottom in the clear water of the Sea of Cortez. It seemed to be having the effect a line of tanks would have had. And now scientists have quantified the damage done by dragging nets across the bottom. Think of it as clear-cutting.

The December 1998 issue of Conservation Biology carries seven reports on what fishing does to the bottom. The lower part of the net opening moves across the bottom like a road grader, skimming off the top few inches of mud or sand and most of the invertebrates that live there, the worms and amphipods and anemones that biologists know as the benthic community. The net crushes or buries some of the organisms. Others are suddenly exposed to predators as the net sweeps away their hiding places, the complex structures created by organisms such as soft corals, brachiopods, bryozoans and crinoids. Some benthic creatures live a long time (Atlantic quahog clams live for up to 200 years, and some deepwater corals live more than 500 years) and grow and reproduce slowly; recovery from a trawler pass can take years.

Humans aren't the only ones disturbing the seabed. Feeding whales and walruses leave what look like bomb craters in the sediment. We humans do operate on a grand scale, however. Les Watling, of the Darling Marine Center at the University of Maine, and Elliott A. Norse, of the Marine Conservation Biology Institute, in Redmond, Washington, calculate that mobile fishing gear covers an area equal to all the continents' shelves, 10.8 million square miles, every two to four years. The United Nations estimates that about 39,000 square miles of forest is cut every year. Thus the damage to the seabed occurs over an area 150 times as great. Until very recently, few people took much notice. Perhaps it's because "the oceans, unlike forests, still look like the oceans after we've removed their contents," suggests James T. Carlton, of Williams College-Mystic Seaport, in Connecticut, in an accompanying editorial. On a deeper level, he proposes that while we have a pretty fair idea of what we've done to the terrestrial landscape and its biodiversity, we know very little of our impact on the oceans — outside the obvious cases of declining fisheries. He adds that even as long as 100 years ago life in the oceans was already profoundly affected. Carlton asks: "Where is the large, beautiful hydroid Ectopleura americana, first and last collected on a ship's hull in 1879 in Long Island Sound?... Which species were carried around the world by ships for 300 years prior to 1800 that we pretend are now native everywhere they occur?"

We don't know anywhere near as much as we'd like to about the world's oceans and the state of their biodiversity, but we do know there are fisheries in decline all over the world. Many of those declines have been blamed on overfishing, but now we are learning why the stocks don't always rebound even when moratoriums are enacted. The marine equivalent of clear-cutting leaves little or nothing for remnant populations, juveniles and their prey to live on and no place to hide.

In the Northeastern United States, and in the Gulf of Mexico and the Pacific Northwest, fishermen are suffering. Boats are tied up. Ancillary businesses are going under. In Canada, where 30,000 fishermen are no longer allowed to fish, communities are dying. Governments are doing what they can. In New England the federal government is trying to open markets for previously unsalable fish, such as skates, sculpins and dogfish. But some conservationists in turn are horrified that more species are being targeted. "People who would be outraged to find blue herons or raccoons in the meat section at the supermarket are willing to accept the hunting and marketing of previously unexploited species of marine life, wrote Tatiana Brailovskaya, of the Nereus Project, in Newcastle, Maine, in Conservation Biology.

If you drive up from Boston and then cross the Annisquam River into Gloucester, you will pass a memorial to the more than 7,000 men lost at sea from 1623 to 1923. Once, fishing was everything. Now modern-day Gloucester, the city of Sebastian Junger's current best-seller, The Perfect Storm, continues its decline as a fishing port. We've come perilously close to licking the platter clean. Large parts of the fishing grounds are closed, certain species are off-limits. Some species may recover. I just hope I never see the day when the last Gloucester fishing boat has passed the breakwater coming home from the sea and there will be no more.

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