Overfishing

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Overfishing

Introduction

Overfishing refers to a situation in which the fishing industry removes more fish than can be replaced by reproduction of the fish left in the ecosystem. Due to improvements in technology, fishing yields have grown dramatically over the last 50 years. The quantity of fish removed from the ocean by fishing probably approaches the maximum sustainable yield of the ocean. There are several examples of fisheries that have been decimated by overfishing, such as the cod fishery in the North Atlantic and the New Zealand orange roughy industry.

One of the major problems associated with the fishing industry is the high percentage of bycatch that is removed from the ocean during fishing practices. Advances in fishing technology and pressure by non-profit organizations are helping to improve fisheries management to prevent overfishing.

Historical Background and Scientific Foundations

Fish represent about 16% of the protein in the human diet and this percentage is much greater in developing countries. According to the United Nation’s Food and Agricultural Organization (FAO), in Asia, 30% of the animal protein in people’s diet comes from fish; in Africa about 20% comes from fish; and in Latin America fish contribute about 8% of the animal protein to people’s diets. More than 100 million people depend on the fishing industry for employment in developing countries alone.

Approximately 90% of all fisheries’ yield are marine fish. The most common types of commercial fish include small pelagic species like anchovies, anchovetta, sardines, and herring. Larger open ocean predators like the jacks, tunas, billfish, bonito, redfish, mackerels, and basses are also important to commercial fisheries. Other fished species include swimming invertebrates such as krill, shrimp, crab, lobster, oyster, scallop, octopus, and squid. Marine algae including Ulva, Poryphyra and Laminaria account for roughly 3% of the marine fisheries.

The quantity of fish caught by fishermen has increased rapidly over the last five decades. Since 1950 the annual fish yield increased from 21 million tons to around 90 million tons. The Peruvian anchoveta is the most caught marine species, with a yield of around 10 million tons. China catches the most fish worldwide, with an annual yield approaching 17 million tons.

The great growth in the fishing yield is a result of several factors. Most fish are caught by commercial fishermen from large fleets of ships. The technology employed by these fishing businesses is vast, including satellite sensors, sonar tracking, scouting ships, and spotting airplanes. Enormous factory ships act as entire processing facilities with spaces for cleaning, canning, and freezing all on board. These great fleets of ships have been able to exploit fishing grounds that were largely inaccessible in the past, particularly in the Southern Hemisphere.

Even with the immense fishing effort, the yield of fish taken from the ocean has leveled off, and even declined since the 1980s. Fisheries experts estimate that the maximum sustainable yield that can be removed from the oceans is somewhere near 110 to 150 million tons. The current yield is extremely close to the lower end of this estimate. When so many fish are taken from the ocean that the remaining fish cannot replenish those removed by breeding, the condition is known as over-fishing.

In 2006, the FAO’s report on the state of the world’s fisheries showed that almost 80% of the fisheries were threatened by overfishing. More than 25% of the world’s fish stocks were overexploited or depleted. More than half of the total fish stocks were exploited. The report estimates that at least 90% of the world’s largest predatory fish, like the oldest tuna and swordfish, are no longer in existence.

One of the most dramatic examples of overfishing occurred in Newfoundland, Canada. The cod fishery had thrived in the region for hundreds of years. However, years of overfishing driven by poor management practices depleted the standing stocks so greatly that the entire fishery collapsed in one year. In 1992, more than 35,000 people lost their jobs when the cod did not return at the beginning of the fishing season. The fishery, and the region’s economy, are still in a state of disrepair.

Other examples of similar fisheries crashes as a result of overfishing exist. Orange roughy from waters near New Zealand became extremely popular in the 1980’s for its mild, delicate flavor. The fish grows extremely slowly and can live as old as 100 years. It is not able to reproduce until it is 25 to 30 years old. As fishing pressure removed the older, larger fish, the remaining orange roughy were too young to reproduce. After only 13 years of fishing for orange roughy, the species was nearly extinct.

Impacts and Issues

Management of the fisheries industries has the goal of preventing overfishing. The objectives are to maximize the yield of fish, while at the same time maximizing the economic yield. This has led to poor decisions that deplete standing stocks of fish and disrupt ecosystems that sustain commercial fish populations. When fish catch drops, management practices often increase the number of fishing licenses and the number of boats allowed in the fishing fleet. Some organizations estimate that there are currently 2 to 3 times the number of vessels fishing the oceans than are required to catch the maximum yield. In order to support these fishing efforts the governments of the United States, Japan, the European Union, and Russia all subsidize fishing fleets, which significantly exacerbates overfishing.

One of the most notable problems contributing to the depletion of fisheries stocks in the ocean a known as bycatch or bykill. Bycatch refers to the collection of non-target species by fishermen. Most often bycatch is removed from the catch and thrown overboard back into the ocean, where, presumably, it dies. Bycatch has enormous ramifications. Approximately 20 million tons of fish food are lost to bycatch per year. It is estimated that the tuna fisheries kill one million sharks a year. In the shrimp industry, approximately 80% of the catch is bycatch. Bycatch is not restricted to fish; marine mammals, birds, and turtles are all killed as bycatch.

Advances in fishing technology can significantly reduce bycatch. Circle hooks are specially designed to catch the species of fish that fishermen can sell in mar-

WORDS TO KNOW

AQUACULTURE: The farming of fish or shellfish in freshwater or saltwater.

BYCATCH: Non-target species killed in the process of fishing.

SUSTAINABILITY: Practices that preserve the balance between human needs and the environment, as well as between current and future human requirements.

kets. Specially shaped nets exclude species that will otherwise become bycatch. Harpooning large species with spot planes, rather than using long lines or drift nets, also significantly decreases bycatch. Finally, producing fish in aquaculture farms brings fish to market, without creating bycatch.

Government oversight of fishing is often inconsistent and poorly regulated. There are few international regulations that control fishing in the open ocean. Exclusive Economic Zones (EEZs) are waters within 200 mi (321 km) of a country’s coastline. Within these strips of ocean, governments can regulate fishing. However 64% of the ocean falls outside these regions and international laws are few and poorly enforced.

Since the fishing industry is market driven, some non-profit organizations have begun publishing seafood guides to urge consumers to make careful choices about the types of fish that they eat. By discouraging consumption of fish that are caught with significant bycatch or in poorly managed fisheries, these organizations hope to influence the industry and its managers to make better decisions about sustaining fisheries. In particular, Monterey Bay Aquarium has developed a Seafood Watch program that helps businesses and consumers make choices for healthy oceans. One of the major successes has been the publication and distribution of pocket guides recommending consumers buy sustainable species of fish when they are shopping.

Other groups have put pressure on fish sellers to identify the source of the seafood they sell as well as the methods used to harvest it. For example, the grocery chain Whole Foods Market is committed to only selling fish from well-managed fisheries. The Marine Stewardship Council (MSC) is a British organization that identifies and certifies sustainable fisheries.

BIBLIOGRAPHY

Books

Clover, Charles. The End of the Line: How Overfishing Is Changing the World and What We Eat. Berkeley: University of California Press, 2008.

Ellis, Richard. The Empty Ocean. Washington DC: Island Press, 2004.

Garrison, Tom. Oceanography: An Invitation to Marine Science, 5th ed. Stamford, CT: Thompson/Brooks Cole, 2004.

Web Sites

Food and Agriculture Organization of the United Nations. “Fisheries and Aquaculture Department.” 2008. http://www.fao.org/fishery/ (accessed March 24, 2008).

Food and Agriculture Organization of the United Nations. “The State of World Fisheries and Aquaculture.” 2004. http://www.fao.org/docrep/007/y5600e/y5600e00.htm (accessed March 24, 2008).

MarionBio.org. “Sustainable Fisheries.” February 17, 2008. http://marinebio.org/ (accessed March 24, 2008).

Overfishing.org. “Overfishing—A Global Disaster.” 2007. http://overfishing.org/ (accessed March 24, 2008).

United Nations. “Overfishing: A Threat to Marine Biodiversity.” http://www.un.org/events/tenstories_2006/story.asp?storyID=800 (accessed March 24, 2008).

World Wildlife Fund. “Problems: Poorly Managed Fishing.” February 29, 2008. http://www.panda.org/about_wwf/what_we_do/marine/problems/problems_fishing/index.cfm (accessed March 24, 2008).

Juli Berwald

Environmental Science: In Context