What is Overfishing and How Does it Affect the Ecosystem?

Overfishing involves taking more fish from the water than is sustainable, which means the number of individuals removed is more than the breeding or recovery rate of the population.

This leads to a decline in the numbers of these species, which can happen rapidly, causing issues within the ecosystems and affecting the stability of the environment.

Research shows that globally we could experience the collapse of marine seafood populations by 2050, and collapse means the species we rely on for consumption will have declined by a massive 90%.

Today, 3 billion people rely on seafood as a primary protein source and in 2018, global fishing totals are estimated to be around 179 million tonnes each year. Studies show that at least a third of all assessed fishing practices are done so in an unsustainable way, and the species targeted are declining rapidly.

Fishing unsustainably results in economic problems as it leads to less marine life available to catch and therefore sell, but what are the environmental impacts?

What Impacts Does Overfishing Have on the Ecosystem?

1. Overfishing Destroys Delicate Ecosystems

The major problem with overfishing is that it depletes the amount of marine life in the water, which causes ecosystems to collapse. This drives further environmental destruction, as each individual species plays an important role in maintaining the health of the habitat they live within.

Specific species are often targeted in the fishing industry in relation to what consumers want, which leaves many environments depleted of a key member of the food chain.

The coral triangle in Southeast Asia is an area facing overfishing issues of many species, including tuna, which is one of the worst affected.

Big fishing practices often take advantage of marine life that gathers in large numbers, sometimes to hunt, for safety, or to spawn at specific times of the year. Collecting fish in this way can reduce populations very quickly due to many reproducing adults being caught at once, leading to fewer offspring being produced or making it to adulthood.

This negatively impacts species further down the food chain, and when fishing occurs on coral reefs using nets, it is generally the herbivorous fish that are caught. These fish play an important part in keeping the reef healthy, by preventing other species from overpopulating and balancing algae levels.

Fewer marine creatures on the reef to keep it healthy means the coral is more exposed to extreme weather events and climatic changes like increases in water temperature that lead to the death of the coral reefs.

2. Overfishing Leads to More Marine Environments Being Targeted

It is a vicious cycle; overfishing leads to fewer fish in the ocean, so boats must venture into new locations, or trawlers go to deeper parts of the sea, which destroys even more ecosystems.

To put this in perspective, despite the number of fishing boats doubling between 1950 to 2015, the number of fish caught compared to the effort was a fifth less. This means that more areas are being fished, but fewer fish are being caught each time.

Trawling drives overfishing as it involves a wasteful practice of large nets, sometimes miles long, being dragged through the ocean or across the seabed which catches every animal in its path.

3. Overfishing Causes the Decline of Other Marine Animals

Reducing the number of fish in the ocean affects the food sources of many other marine animals and leads to a decline in their numbers.

Overfishing also results in many creatures ending up as bycatch, particularly with trawling fishing practices as the nets catch every creature in the area. This means many marine mammals like whales, dolphins, and porpoises, as well as turtles, sharks, and even seabirds, die in these nets, which has a dramatic impact on the environment.

In fact, one-third of all sharks, rays, and related species are at risk of extinction because of overfishing, and at least 650,000 marine mammals are caught as bycatch in nets each year.

4. Ocean or Lake Dead Zones

Damage to the biodiversity of an ecosystem can cause ocean or lake dead zones, which are areas with low oxygen levels that most organisms cannot survive in. Worldwide, there are around 400 ocean dead zones which equal an area larger than the United Kingdom, or the state of Oregon.

Overfishing can lead to these dead zones because important species, like Cod, are lost, which unbalances the ecosystem and can lead to increases in certain species such as algae.

With no other species to regulate numbers, algae can multiply, leading to large algal blooms that take oxygen out of the water and starve the water.

Populations of other species are therefore forced to leave, or even die out, resulting in damage to the ecosystem.

Why Does Overfishing Happen?

Fishing is not Well Managed or Controlled

Despite research highlighting the negative effects overfishing has from both an environmental and economic perspective, it is still commonplace because the industry is poorly governed and managed.

There is a hesitancy from governments to place stricter controls on fishing or to tackle illegal fishing because of the large economic benefits of the industry.

The nature of the ocean, being so vast with no clearly defined borders, also poses an issue for implementing policies and control measures.

Harmful Subsidies Fuel Overfishing

Subsidies are generally used to support economic growth in specific industries. It is the harmful subsidies that are provided for certain fishing practices that cause problems such as overfishing, as they fund industries that without it, will not make a profit.

An example of this is subsidies to build new fishing vessels or those that go towards industrial trawling boats to cover fuel costs.

Research outlines that in 2018, over $20 billion of subsidies were used to fund unsustainable fishing practices across the world that lead to overfishing.

Subsidies are not necessarily the problem, but it is what this funding is supporting, which currently is a model that results in overfishing – as fish stocks decrease, fishing efforts must increase for the companies to make a profit. This is unsustainable and part of the reason fish stocks are so low.

Fishing is a Big Part of Many Cultures

It is important to outline that there are many cultures and communities that rely on fishing for survival and have done so for many years. Fishing in a small-scale operation using knowledge, experience, and respect for the local ecosystems is not the issue.

It is when organizations take advantage of these resources and local knowledge about species’ behavior or habitat, to create as much profit as possible, that the biodiversity suffers.

What Can We Do to Stop Overfishing?

1. Consume Less Fish

One of the best ways to prevent overfishing is to reduce the amount of fish you consume, and ensure the fish you eat is caught in a sustainable way. This is particularly relevant if you are living in a developed country and eating fish that has been imported from other parts of the world, as you cannot guarantee the sustainability of these fishing practices.

It is not as simple as trusting labels that claim fishing regulations are followed, as globally this is not well managed. If you do purchase fish, shop locally, choose sustainable species, and buy from brands that you trust.

2. Introduce Policies

Governments and global organizations need to work together to end illegal fishing, adjust subsidies so they promote sustainable fishing, and introduce policies that prevent overfishing.

4. Research

Funding research into fish populations, the health of marine ecosystems, and the effects of current fishing techniques will also reduce overfishing as there is clear data to support laws and policy.

Additionally, changes are more likely to occur if we share the idea that there are economic benefits for the fishing industry if we eliminate overfishing, as well as environmental benefits, due to more abundant marine life populations.

5. Creating More Marine Parks

Creating more Marine Parks where fish are protected is a fantastic way to support ecosystems as it provides safe areas for fish to live and reproduce, therefore stabilizing populations.

Research has shown that implementing protected marine areas can increase fish populations by 400% in just 11 years, allowing ecosystems to recover, yet still allowing designated areas where fishing can occur.

6. Support and Promote

Supporting and promoting the rights of local, small-scale fishing communities and learning from them how to appropriately protect marine life will also help to transform ecosystems across the world.

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