Overfishing is the catching and removal of fish or other animals from oceans, rivers, and lakes at a rate too high to allow wild populations to recover. Overfishing occurs with mass commercial fishing—which involves catching large numbers of fish over a short time—or poor management of a fishery. A fishery is an area where a certain fish is caught. Overfishing endangers the ocean ecosystem as well as people throughout the world who rely on seafood. An ecosystem consists of all the living things in an environment and the nonliving things on which they depend. 
History
Throughout human history, people have fished and gathered other resources from oceans and rivers. Prior to the 1800’s, small fishing crews used traditional practices to harvest marine life at rates that usually allowed stocks to replenish from year to year. During the late 1700’s and early 1800’s, however, great changes took place in the lives and work of people in several parts of the Western world. These changes are called the Industrial Revolution. During the Industrial Revolution, the human population began to expand rapidly. Technology developed during this time improved fishing, food preservation, and transportation. Faster, more efficient fishing boats could harvest more fish. The catch could also be preserved and transported across long distances to growing markets.
Despite these changes, people continued to treat products of the ocean as unlimited renewable resources. Leaders failed to put into place rules and laws to protect the ocean ecosystem. Consumers became used to being able to purchase fish and other products derived from marine animals at affordable prices.
As the changes of the Industrial Revolution took hold, stocks frequently collapsed in fisheries near industrializing nations. Atlantic cod and herring fisheries declined in the mid-1800’s. As cod became scarce, fishing crews began taking Atlantic halibut, which had previously been considered a nuisance bycatch. Bycatch is any animal fishing crews catch that they cannot or do not wish to keep. Halibut populations collapsed in just a few decades. Mackerel fisheries crashed in the 1880’s. 
People hunted whales to make lamp oil, cosmetics, and other products developed during the Industrial Revolution. As the years wore on, ever-more advanced whaling fleets extracted more and more whales from the sea. More whales were killed during the first 40 years of the 1900’s than over the preceding 400 years. The number of whales killed worldwide peaked in 1962, when 66,000 were killed. Many kinds of whales became rare, and some species nearly went extinct.
During the mid-1900’s, many countries expanded their fishing fleets. These fleets increased their fish catch along their home coasts as well as in distant waters. As a result, the fish harvest generally increased each year. But at the same time, overfishing severely reduced stocks in some fishing areas.
In deeper waters, crews found stocks of edible varieties of fish that had not been consumed in large numbers by people. Due in part to the declining catches of usual varieties of fish, the fishing industry marketed these new catches to consumers. One aspect of this campaign was giving the fish more appealing names. For example, the Patagonian toothfish was called the Chilean sea bass, and the slimehead became the orange roughy. These species grow slowly, making them prone to overfishing. Their populations collapsed in the 1990’s. 
Combating overfishing
Regulations
are the best way to combat overfishing. Oversight by the fishing industry, state governments, and international organizations is necessary to enact and enforce such regulations and enable fisheries to replenish their stocks.
The simplest regulation to combat overfishing is to limit the amount by weight that can be harvested for target species. Such limits can be adjusted from year to year to account for such factors as the previous year’s catches or stock assessments. Fishing may also be restricted to certain parts of the year. Such a restriction might protect the species during the breeding season, for example.
Many fish and marine animals can only reproduce once they reach a certain size. Therefore, regulations might impose a minimum size for a fish or other marine animal to reach market. This gives smaller fish an opportunity to grow and reproduce.
Occasionally, regulations may protect fertile females, as they have an outsized role in the replenishing of stocks. This is the case for North American lobsters, where the female carries fertilized eggs on the underside of her body. When lobster fishing crews catch an egg-bearing female, they make a small notch in her tail and release her. They also release any lobsters that possess a notched tail, even if they are not bearing eggs. Such a notch lasts for a few years. 
Reducing bycatch.
Bycatch can exacerbate (make worse) the effects of overfishing. Fishing crews return bycatch to the ocean, but most of the animals are stressed or injured, and many die. Therefore, if undersized individuals are caught as bycatch, it further damages the fishing stock. To combat this, fishing crews use special equipment that enables smaller individuals or non-target species to avoid or escape capture. 
Aquaculture
has been proposed as an alternative to commercial fishing. Aquaculture is the controlled raising of aquatic animals and plants. Aquaculture can damage the ecosystems where it is located, however. For example, waste runoff from farmed species can lead to water pollution. Aquaculture species are often fed fish meal (ground-up fish). The collection of fish to produce fish meal can itself cause overfishing. 
Accreditation
of seafood as sustainable can give consumers the power to choose products that were harvested sustainably. In 1997, the Marine Stewardship Council (MSC), an international non-profit organization that works to protect oceans, established standards for sustainable fishing. The council marks fish at grocery stores with a special sticker if the fishing practices and choice of species meet its standards. However, critics argue that the MSC and other such accrediting bodies suffer from a conflict of interest because fishing companies pay them for accreditation.
Obstacles to ending overfishing
Obstacles to ending overfishing include illegal, unregulated, and unreported fishing. Such activities include fishing without a license, failing to report catches, keeping protected or undersized fish, and fishing in closed areas. Illegal fishing can damage the stocks of a fishery.
As larger, predatory fish have become scarce, commercial fleets have been “fishing down the food chain”—that is, they fish for smaller fish that are prey for the larger fish. The process of fishing down further upsets the ecosystem by depleting food resources, making it difficult for stocks to recover. 
Even if overfishing ceases in a collapsed fishery, fish populations may never recover. After a collapse in the 1800’s, Atlantic cod fisheries eventually returned to producing a small fraction of the previous catch. But they continued to be overfished and collapsed again in 1992. Despite restrictions, Atlantic cod have not significantly recovered. Scientists speculate that their recovery has been prevented by competition from other species in the cod’s former range and the warming of waters caused by climate change.
