The Pelagic Plague

No method of commercial fishing is more destructive of marine ecosystems than longlining. on any given day 100 million baited hooks dangle from giant trotlines in all the world’s oceans. a single mainline (and each vessel tends many sets) may be 60 miles long and drape two thousand 1,200-foot branch lines. longlines kill sea turtles, sea birds, marine mammals, sharks, billfish, tunas, mahi—in short, any creature that gets tangled in the cord, snagged by a hook or that eats the squid or fish bait.

Longlining was introduced by the Japanese in 1952 when the United States first allowed their provisional government to return to the sea. By 1965, Japanese longliners were stripping marine life from every quarter of every ocean. Later in the decade, Spain and the United States joined the slaughter. By the 21st century longlining had become a free-for-all with more than 40 nations and untold pirate fleets competing for rapidly dwindling resources.

The international commission for the conservation of atlantic tunas (ICCAT)—the body that supposedly manages highly migratory species by setting quotas, leaving most local regulations to member nations—estimated that in 1961, when major longlining was just getting underway, marlin and tuna populations were about double what was needed for maximum sustained yield (mSY).By 1995, ICCAT was reporting atlantic blue marlin down to 24 percent mSY, Atlantic white marlin down to 23 percent mSY, Western atlantic sailfish down to 62 percent mSY and Western atlantic bluefin tuna down to 6 to 12 percent mSY. Since then these declines have accelerated in direct proportion to increased longlining effort.

Worldwide, longlining is causing 95 percent of all mortality of marlin, sailfish and spearfish. By-catch of most billfish and virtually all tuna (which need to swim fast to oxygenate) is discarded dead. the only big fish on the planet doing better than it was a decade ago is the swordfish. and that’s because longliners had plundered the species to the extent that the National marine fisheries Service (NmfS) had to close large nursery areas off the carolinas.

Do you remember how good swordfish tasted when you were a kid; and have you noticed how horrible it tastes now? this is not a function of your maturing palate. the completely selective, sustainable harpoon fishery that longlining replaced produced fish that were brought daily to dockside. today swordfish soak dead in seawater for days; then, after their waterlogged carcasses are winched onboard, they fester on ice for a few weeks. When they finally make it to shore they’re so slimy and disgusting that longline crews sometimes scrub them with bleach. Longlining has slipped under the radar screens of fly-rodders and other light-tackle anglers because—excepting school bluefin and yellowfin tuna, white marlin, sailfish and mahi—the practice targets few fish we commonly pursue.

Why, for example, should we care about the gross by-catch of sea birds and endangered and threatened sea turtles or about the unsustainable slaughter of snappers (other than muttons, which occasionally patrol the flats), groupers, tilefish and sharks (other than makos, spinners, bonnets and blues, which some of us chase)? Because, as 19th and early 20th century philosopher-naturalist John Muir planted by the U.S. Army Corps of Engineers in the Piankatank River as part of an effort to restore dwindling shellfish.

But what have shellfish got to do with angling? Well, they filter seawater. And their unnatural absence in Chesapeake Bay is allowing a proliferation of algae and phytoplankton that blocks sunlight from benthic, oxygenating vegetation thereby killing gamefish forage and gamefish fry while creating a fertile environment for mycobacteriosis, a disease devastating Atlantic striped bass in this, their most important nursery area. Interestingly enough, the one large shark declining less precipitously than the others is the mako.

The Blue Ocean Institute’s Dr. Carl Safina offers this explanation: “I think the reason is that most makos over 400 pounds break off longlines. So there’s probably a pool of breeders out there. We’re seeing a lot of pups and adults, but very few mediums.” Florida has dropped more than 40 percent in the last decade, eat jellyfish too. So do countless species of fish. Annihilation of jellyfish predators by longliners may be much of what’s behind the enormous jellyfish blooms being seen all around the world. Jellyfish are extremely proficient predators of larval fish, including all the ones we target. “You get to a tipping point where the number of jellyfish predators decrease and the number of jellyfish increase,” says Dr. Russell Nelson, chief scientist for the Billfish Foundation. In the 1980s, almost 5,000 leatherbacks nested at Mexico’s Mexiquillo Beach, historically the species’ most important nesting site. Recently the average has been four.

In September 2008, NMFS reported that observers placed aboard selected longliner vessels targeting such bottom fish as grouper and tilefish in the Gulf of Mexico noted, “When one tugs at a single thing in nature, he finds it hitched to the rest of the universe.” Herewith, examples: Sharks reproduce slowly, 70 percent of them bearing live young after long gestation periods and in dog-sized litters. This makes them especially vulnerable to directed and incidental fisheries. Longliners, killing sharks on purpose and by mistake, have knocked most of the larger species down to a fraction of their natural abundance. Sharks are especially fond of eating rays; and as sharks have declined ray populations have exploded. But why should anglers worry about ray overabundance?