Midocean trawlers mine world’s seamounts
Unregulated fishing fleets work fast and deep, but rising cost of fuel may rein them in before laws do.
In the mid-1970s, fishing boats came across great aggregations of a reddish fish around underwater mountains, called seamounts, near New Zealand, a kilometer deep. A century before, fishermen had discovered the same species in the northeast Atlantic. But never had anyone encountered schools this dense. Characterized by a blunt face lined with mucosal glands, the fish wasn’t exactly handsome. But its flesh, which tasted vaguely of shrimp, was white, firm, and delicate. The only problem: the name. The fish was called “slimehead.” So “some smart marketer,” in the words of one expert, rechristened it “orange roughy.” And a new high-end fishery was born.Skip to next paragraph
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For many, it was evidence of a worrisome new trend. Enabled by improved technology, fishing fleets were going farther and deeper than ever before. By the mid-1980s, they had converged on seamounts the world over, seeking deep-water species like orange roughy and Patagonian toothfish (marketed as “Chilean sea bass”). They were now trawling places that, by virtue of their depth and rough topography, were previously off-limits. Many characterize what followed – and continues to occur – as akin to strip-mining: Catch everything as quickly as possible and then move on. Scientists worry that these deep-sea ecosystems populated by long-lived organisms can’t withstand the fishing pressure. But there’s little recourse: Many of the estimated 30,000 seamounts worldwide lie outside national jurisdiction, and the high seas remain unregulated.
Conservationists have long lobbied for regulating international waters. In recent years, the effort has borne fruit in the form of nonbinding agreements. But some, doubting the efficacy of nonenforceable pacts, think high fuel costs are the high seas’ best hope. When it’s too costly to fish the mid-Pacific, fishing vessels won’t go there. But for now, as seamount trawling continues in much of the world, scientists fret that these unique ecosystems may disappear before they can find out what’s there.
Underwater mountains obstruct ocean currents, forcing deep, nutrient-bearing water upward. So seamount ecosystems are fertile compared with the surrounding ocean, and they support unique organisms. Many of them have adapted to the cold, dark conditions with slow growth and long lives. Orange roughy, which reach sexual maturity at between 20 and 30 years of age, can live to be 150.
Some deep-sea corals have been dated to 4,000 years old. They were growing when Moses led the Israelites out of Egypt, says Mr. Norse.
Scientists think that many seamount species are endemic, existing only there. One survey near Tasmania found that perhaps one-third of the invertebrates were endemic. Between 24 and 43 percent were new to science. Researchers have also found that seamounts closed to trawling had double the biomass and nearly half again as many species compared with those that were trawled. The high rate of unique species, plus the ecosystem’s sensitivity to disturbance, leads many to conclude that seamount trawling will lead to extinctions.
“To simply remove species from the planet, particularly on a large scale, is something we can’t go back on,” says Tony Koslow, a deep-sea ecologist at Scripps Institution of Oceanography in La Jolla, Calif., and lead scientist on the Tasmania surveys. “It’s just ethically wrong if it can be avoided.”
Soviet ships were the first to fish seamounts when, in the late 1960s, they stumbled across large schools of armorhead along the Emperor Seamounts northwest of Hawaii. Less than a decade later, Soviet and Japanese fleets had harvested 1 million metric tons of armorhead. The stocks have yet to recover.