Trouble Down Below - Fishing Methods

Fishing Methods

For millenia, fishermen have sailed to sea in boats. For millenia, fisherman have risked their lives pursuing fish. And for millenia, fisherman have sought ways to increase their catch while easing their exertions. The tools of their trade remain the same as they always have been: nets and hooks, knives and twine. While technology has modernized some fisheries, others remain so basic they would be recognizable to the fisherman of the Galilee. The real revolution in fishing is its impact on the environment. Gone are the days of the limitless sea. Gone are the days when a few fisherman pulling in a few nets could feed the many. The many now have become billions. Human hunger, more than economic profit, fuels the unprecidented onslaught of the world's oceans. To feed that hunger, millions of fisherman will this day sail to sea. Most will employ one the methods listed below.

Purse Seine
A purse seine is a long net made of heavy nylon mesh, with floatation corks along its top and lead weights along its bottom.. Deployed by two boats working in tandom, purse seines are towed through the water in a long sweeping arc. The bottom of the net is then pursed shut by a stout line that runs though a series of rings suspended along the seine's bottom. Once pursed shut, the net forms an enormous bowl that traps entire schools of fish. Using a hydraulic block suspended from the boat's mast, the net is hauled aboard and the fish deposited into the boat's hold. This fishing method is used in the Alaskan and Puget Sound salmon fisheries, as well as the Pacific herring and tuna fisheries. Prior to international agreements modifying seining techniques, South Pacific tuna seiners killed hundreds of thousands of porpoise that frequently accompany schools of tuna.

Longline
A longline is a single mainline on which hang branch lines called "ganglions," to which baited hooks attach. Longlines of 50-miles or more in length, hung with thousands of hooks, are commonly used when fish are thinly dispersed over a wide area. Longlining is typically used in the Pacific tuna, black marlin, halibut and black cod fisheries. Frequently, longlines catch other species, including sharks, skates and sea birds. An estimated 180,000 seabirds are killed each year by longlines. In 1998 alone, more than 60,000 sharks were caught and killed, most for their fins, in Hawaii's longline fishery.

Drift Gillnet
Gillnets are constructed of thin, nearly transparent monofilament fishing line. Suspended on the ocean surface by a series of floats, drift gillnets can stretch for miles and are used to catch tuna, squid and salmon. But drift gillnets catch more than just commercially valuable species. Thousands, perhaps millions, of seabirds, dolphins, seals and non-targeted fish species have died in drift gillnets. For that reason, they have been banned from the South and Central North Pacific, though they are still used in the Mediterranean Sea, the Indian Ocean, and the Baltics and Irish Sea.

Trawling
A trawl is a large, heavy, sock-shaped net towed under the ocean surface though the water column or across the seafloor. Trawls are held open by large metal or wooden doors that can weigh from the hundreds to the thousands of pounds. The leading edge of the net is weighted with heavy metal balls and chains and rubber rollers and chaffing gear.
Bottom trawling, or dragging, has been heavily criticized for damaging vital seafloor habitats. As the heavy net scrapes along, it crushes or buries a host of species that live in the mud and rocks. By damaging the ocean floor's fragile ecosystem, trawling disrupts fragile links in the marine food chain. Though it has been implicated in the collapse of the cod, haddock, Pollock and flounder fisheries, trawling remains commonplace in the Atlantic.