Overfishing Facts



Modified: 31 May 2023

Overfishing Facts, 400 tons of Chilean jack mackerel

Scientists today agree that overfishing makes up one of the greatest threats to the future of our oceans. Not only does it threaten so many fish and aquatic species with extinction, but it can also push the oceanic ecosystem to collapse. Learn more about this threat to the natural world with these 40 overfishing facts.

  1. An estimated 34% of the world’s fish stocks suffer from overfishing today.
  2. The Mediterranean and Black Sea’s fish stocks suffer from an estimated 62% overfishing.
  3. The Atlantic Ocean’s fish stocks similarly suffer from an estimated 59% overfishing.
  4. On average, only an estimated 39% of the Pacific Ocean’s fish stocks suffer from overfishing.
  5. Depleted fish stocks cost the global fishing industry an estimated $50 billion every year.
  1. Overfishing destroyed the tuna industry in the Adriatic Sea in 1954.
  2. The Peruvian anchovy industry similarly collapsed thanks to overfishing in the 1970s.
  3. Overfishing wiped out the bull walleye in North America’s Great Lakes in the 1980s.
  4. The collapse of the Newfoundland cod industry led Canada to ban fishing in the Grand Banks in 1992.
  5. In 2002 the Rio+10 Summit warned that overfishing threatened food supplies for millions of people worldwide.
  6. The British government officially admitted in 2007 that overfishing has brought sole populations in the Irish Sea and other nearby waters to the brink of collapse.
  7. The UN stated in 2008 that thanks to shrinking fish populations, up to half of the world’s fishing fleets suffer from redundancy.
  8. Environmental organizations warned in 2015 that fish species like bonitos, mackerel, and tuna, had suffered a 74% population drop since the 1970s.
  9. As of 2021, overfishing has also contributed to a 71% drop in the world’s shark and ray populations.
  10. The Nature journal in 2021 also stated that overfishing has become the biggest threat to the ocean’s biodiversity.
  1. The fishing industry has a financial incentive to oppose anti-overfishing measures.
  2. Illegal fishing accounts for up to 33% of the world’s fish catches.
  3. Overfishing has directly contributed to increased rates of schistosomiasis infection in Africa.
  4. Global jellyfish populations have also risen, thanks to overfishing.
  5. As fish stocks drop, thanks to overfishing, the market price of fish also rises in response.
Table of Contents

Scientists have specifically defined what counts as overfishing.

Overfishing simply means catching so much fish in a given body of water that those left behind can’t reproduce enough to replace those who have been caught. This can take place in both freshwater and marine environments, with underpopulation as its first effect. Other effects of overfishing include resource depletion, reduced growth, and low biomass. While fish can recover from overfishing, it would also depend on whether the ecosystem can support their recovery or not. 

Overfishing can result in what scientists call an ecosystem shift.

Ecosystem shifts involve abrupt, large-scale, and long-lasting changes in an ecosystem. Scientists also call it a regime shift, with a regime referring to the way an ecosystem’s built, as well as how it works. Usually, the loss of one or more parts of an ecosystem will cause changes in the rest. It may also cause it to collapse, but it’s also possible for another species or factor to simply replace the lost part of the ecosystem. This replacement could then completely change how the ecosystem works, resulting in a regime shift.

An example of this involves the overfishing of trout, which may allow carp to replace them as the dominant fish species in a given environment. More than that, the carp become so dominant that trout simply can’t recover from overfishing, or even maintain a breeding population at all.

Bycatch also contributes to overfishing.

Bycatch refers to unintentionally catching other fish and aquatic species with commercial species when fishing. As bycatch typically has no commercial value, fishermen usually just dump it back into the sea. In theory, doing so lets them live back in the sea, but in practice, bycatch usually die from injury or shock from getting caught in the first place. On average, bycatch makes up to 25% of all fish caught, and in some cases, can go even higher. For example, bycatch in shrimp fishing actually accounts for up to five times the commercial catch. This means many fish and other species die for no reason, further adding to the effect overfishing has on the environment.

Overfishing Facts, Shrimp Bycatch
Photo by NOAA from Wikipedia

People have tried to find ways to reduce bycatch.

One way of doing so involves banning fishing in areas where bycatch tends to become high from how so many species live there. Another way involves the use of Bycatch Reduction Devices (BRDs), though, this can become expensive. That said, they do work, with BRDs noted as having reduced bycatch by 30% to 40%.

Governments have also banned longline fishing, as this method can cause very high bycatch rates. Other governments have also banned the practice of throwing away bycatch at all. By forcing fishermen to keep everything they catch, this also forces them to care about bycatch. This, in turn, gives incentive to avoid or reduce bycatch from how they can’t profit off of it.

Bycatch doesn’t always get thrown away, though.

In some countries, usually in Asia, Africa, and Latin America, bycatch may get sold at the market. They usually sell for lower prices, marketed as assorted seafood or even as a seafood medley. In other cases, bycatch gets ground up, usually for making organic fertilizer, but also as fish meal or even as food for fish farms. Asian countries, in particular, use bycatch as an ingredient in producing fish sauce. Bycatch also gets used as an ingredient in making fish paste or fish cakes, either for domestic use or export.

Growth overfishing makes up one kind of overfishing.

This involves catching fish with an average size less than the maximum yield per fish. This, in turn, results in an overall smaller yield per catch than if the fish got caught after growing much bigger. Scientists have pushed to counter growth overfishing by reducing fishing mortality, which would give fish left behind to grow bigger. Doing so maximizes the yield per fish, and in turn, results in an overall bigger yield per catch.

Recruitment overfishing makes up another kind of overfishing.

This makes up the most common kind of overfishing, where the adult population gets so depleted that fish can’t reproduce enough to maintain their population. Scientists and other concerned parties have pushed for various ways to counter this kind of overfishing. These include moratoriums, quotas, and even minimum size limits, all of which work by keeping biomass within acceptable levels. Doing so allows breeding populations to stay stable, which in turn, prevents overfishing overall.

Ecosystem overfishing makes up the final kind of overfishing.

This makes up the most devastating kind of overfishing when an entire ecosystem either collapses or changes as a result. We’ve already mentioned the case of the carp and trout earlier, but another example involves the overfishing of predatory fish. As their numbers drop, the population of prey fish sharply increases in turn. As prey fish typically grow smaller than predatory fish, this can then lead to growth overfishing. Specifically, fishermen must make do with the smaller prey fish, leading to overall smaller yields. This, in turn, can force fishermen to catch more fish to make up for the deficit, making the overfishing problem even worse.

Fishing catch in Uppuveli beach
Image from Adobe Stock

Overfishing does have acceptable levels.

The idea has economic reasons, as fishermen have to make a profit, thus, can’t always strictly follow minimum requirements for their line of work. One form of acceptable overfishing involves biological overfishing, where overfishing only slows down breeding rates, but overall keeps the population stable. Then we have bioeconomic overfishing, where fishing keeps to the maximum profitable yield. Specifically, fishermen don’t always catch the most fish they can, but the most fish they can actually profit from.

Scientists have developed ways to measure fishing capacity.

It depends on whether the focus involves input or output, but the result always aims to show whether the fishing population stays stable or not. An input focus tries to measure fishing capacity based on how much money gets spent to keep a fishing business running. If more money gets spent than made, then it means fishing capacity has become too low to stay profitable. In contrast, an output focus tries to measure fishing capacity based on the maximum profitable yield. In this case, if fishermen stop earning more despite making bigger catches, then they’ve exceeded their fishing capacity.

The UN Convention on the Law of the Sea (UNCLOS) covers overfishing.

Specifically, Articles 61, 62, and 65 all include overfishing in their mandates. Article 61 makes nations responsible for making sure that ocean life in the Exclusive Economic Zones (EEZs) don’t get overexploited. That same article also mandates that nations must work to restore endangered species within their EEZs. Similarly, Article 62 notes that while nations have the right to develop their EEZs, they can only do so within the limits of Article 61. Finally, Article 65 gives coastal nations the right to use any lawful means necessary to protect marine mammals in their territorial waters.

Some observers describe overfishing as an example of a tragedy of the commons.

A tragedy of the commons refers to how people with common access to unregulated resources will not only exploit, but deplete them out of self-interest. The term originally applied to how shepherds and other animal herders in Britain would allow their flocks to graze common grounds to depletion. Now, observers note that the same term could apply to overfishing, or how fishermen deplete fishing grounds in international waters. 

Governments have several ways to control overfishing with.

We’ve already mentioned a few of them before, but those make up only a few of the ways governments try to control overfishing. Other methods include bag limits, which sets a maximum tonnage of catch fishermen can fish at any one time. There are also closed seasons, similar to hunting seasons on land, with fishermen only allowed to fish in that time. The declaration of marine reserves and protected areas also make up another way to control overfishing, giving fish places where they can breed and grow without fear of getting caught.

Fishing subsidies may contribute to overfishing.

Nations use fishing subsidies to reduce the costs local fishermen have to pay in order to operate their livelihoods. This, in turn, encourages larger catches, keeps market prices low, and protects local fishermen from foreign competition. However, while subsidies have plenty of economic benefits, scientists argue that it also encourages overfishing. They argue that removing subsidies would force fishermen to focus less on quantity, and more on quality. This would not only reduce overfishing, but possibly even diversify people’s diets. It would also introduce competition to local markets, which may have economic benefits of its own.

Aquaculture may provide an alternative to overfishing.

Simply put, aquaculture involves fish in captivity, usually in the form of commercial fish farms. This allows for the development of new fish stocks, and privately owned ones at that, which offer an alternative to natural ones. The private nature of fish farms means owners have more incentive to focus on quality as well. Fish farming started out small, and only started to grow in the 1970s, and began to overtake natural fishing in the 1990s.

Today, fish farms actually produce about half of the world’s aquatic harvests, and that percentage continues to grow. In contrast, natural fishing has remained steady over that same time. Many scientists now think aquaculture could eventually replace natural fishing altogether, and end overfishing with it. 

fish farms
Photo by Gordon Leggett from Wikipedia

Some critics disagree that aquaculture could stop overfishing.

In particular, they point to how farming carnivorous fish still takes its toll on the natural environment. Salmon farming, in particular, depends on feeding the captive salmon with fish meal and oil produced from prey fish in the wild. Critics also target how the practice of releasing captive salmon into the wild to supplement the smaller salmon, runs in nature. Doing so increases competition for the naturally bred salmon, and only further damages the environment.

Consumer awareness may also help stop overfishing.

This has led to movements against eating seafood completely or only eating sustainable seafood. The latter involves buying farmed seafood, or from sellers known to have programs aimed at maintaining or even increasing fish stocks at sea. Organizations known to certify sustainable seafood include the Marine Stewardship Council (MSC), as well as Friend of the Sea. 

Google has its own program to help raise consumer awareness about overfishing.

They call it Global Fishing Watch, formed in cooperation with the Oceana and Skytruth NGOs in 2016. The program works by uploading data from over 200,000 ships worldwide into a common website. There, the public can freely monitor fishing activities for themselves and see whether or not violations take place in protected zones and similar places. Other participants in the program include the US State Department, as well as the Leonard DiCaprio Foundation.

Efforts to stop overfishing face various obstacles.

The biggest obstacle of them all involves the fact that most of the ocean counts as international waters. This means that no single nation can enforce its laws there, and even enforcing international law runs into problems like jurisdiction, and even international relations. Other obstacles include the difficulty of enforcing national law in territorial waters, especially in poorer countries. There, fishermen usually come from the poorer classes, which governments tend to act more leniently towards. Recreational fishing also allows individuals to bypass regulations meant to stop or reduce overfishing.

Some countries have even tied overfishing to overpopulation.

Bangladesh and Thailand, in particular, have noted that overpopulation only naturally leads to higher needs for food. Meanwhile, fish makes up a common and affordable source of food in both countries. This has led them both to improve family planning programs, which they tie with their environmental programs. Under this logic, bringing their population growth under control would also reduce their environmental footprint, including overfishing.