Drift Net

Drift Net

Ecological damage caused by drift nets

Resources

Drift nets, also called gill nets, are lengthy, free-floating, 26-49 ft (8-15 m) deep nets, each as long as 55 mi (90 km). Drift nets are used to snare fish by their gills in pelagic, open-water regions. Because drift nets are not very selective of species, their use results in a large by-catch of non-target fish, sharks, turtles, sea-birds, and marine mammals. Drift nets are an ecologically destructive fishing technology.

Ecological damage caused by drift nets

Drift-net fisheries have been mounted in all of the world’s major fishing regions, and unwanted by-catch is always a serious problem. This has proven true for pelagic fisheries for swordfish, tuna, squid, and salmon. One example is the drift-net fishery for swordfish in the Mediterranean. This industry kills excessive numbers of striped dolphin and sperm whale, and smaller numbers of fin whale, Cuvier’s beaked whale, long-finned pilot whale, and Risso’s, bottlenose, and common dolphins, along with other non-target marine wildlife. As a result of concerns about the excessive by-catch in this swordfish fishery during the early 1990s, the European Union banned the use of drift nets longer than 1.5 mi (2.5 km) (prior to this action, the average set was 26 mi [12 km] in length). However, some fishing nations have objected to this regulation and do not enforce it.

There are few monitoring data that actually demonstrate the non-target by-catch by drift nets. One measurement was made during a one-day monitoring of a typical drift-net set of 11 mile/day (19 km/day) in the Caroline Islands of the south Pacific. That single net, in one day, entangled 97 dolphins, 11 larger cetaceans, and 10 sea turtles. World-wide during the late 1980s, pelagic drift nets were estimated to have annually killed as many as one million dolphins, porpoises, and other cetaceans, along with millions of seabirds, tens of thousands of seals, thousands of sea turtles, and untold numbers of sharks and other large, non-target fish.

Great lengths of drift nets and other fishing nets are lost at sea every year, especially during severe storms. Because the nets are manufactured of synthetic materials that are highly resistant to degradation, they continue to snare fish, sharks, mammals, birds, turtles, and other creatures for many years, as so-called ghost nets. Because these ghost nets never stop fishing, they pose an important threat to many types of marine animals.

In response to mounting concerns about unsustainable by-catches of non-target species of marine animals, which in some cases are causing population declines, significant regulation has been proposed by various governmental organization. In 1993, the United Nations banned the use of drift nets longer than 1.5 mi (2.5 km) and this ban was supported by the United States. In 2006, the European Union supported plans to completely

KEY TERMS

By-catch— A harvest of species of animals that are not the target of the fishery, caught during fishing directed towards some other, commercially desirable species.

Gill net— A net that catches fish by snaring their gill covering.

phase out drift nets by 2007. In the mean time, they support legislation requiring the use of pingers on drift nets, which act as a deterrent to many marine mammals. Unfortunately, there has been a great deal of resistance from the fishing industry and certain fishing nations to the implementation of even this regulation. In addition, enforcement has proven difficult; illegal, or “pirate” fishers continue to use the extremely destructive, older-style drift nets.

Resources

BOOKS

Berrill, M., and D. Suzuki. The Plundered Seas: Can the World’s Fish be Saved? Sierra Club Books, 1997.

LaBudde, S. Stripmining the Seas. A Global Perspective on Drift Net Fisheries. Honolulu, Hawaii: Earthtrust, 1989.

Norse, Elliott A. Global Marine Biological Diversity. Washington: Island Press, 1993.

OTHER

PBS Transcript of Voice from the Sea. “Getting caught in a net off Sri Lanka.” April 19, 2000. <http://www.pbs.org/odyssey/voice/20000419_vos_transcript.html> (accessed October 13, 2006).

Bill Freedman