Environmental impact of fishing

The environmental impact of fishing includes issues such as the availability of fish, overfishing, fisheries, and fisheries management; as well as the impact of industrial fishing on other elements of the environment, such as bycatch. These issues are part of marine conservation, and are addressed in fisheries science programs. According to a 2019 FAO report, global production of fish, crustaceans, molluscs and other aquatic animals has continued to grow and reached 172.6 million tonnes in 2017, with an increase of 4.1 percent compared with 2016. There is a growing gap between the supply of fish and demand, due in part to world population growth.

Fishing and pollution from fishing are the largest contributors to the decline in ocean health and water quality.^{[citation needed]} Ghost nets, or nets abandoned in the ocean, are made of plastic and nylon and do not decompose, wreaking extreme havoc on the wildlife and ecosystems they interrupt. Overfishing and destruction of marine ecosystems may have a significant impact on other aspects of the environment such as seabird populations. On top of the overfishing, there is a seafood shortage resulting from the mass amounts of seafood waste, as well as the microplastics that are polluting the seafood consumed by the public. The latter is largely caused by plastic-made fishing gear like drift nets and longlining equipment that are worn down by use, lost or thrown away.

The journal Science published a four-year study in November 2006, which predicted that, at prevailing trends, the world would run out of wild-caught seafood in 2048. The scientists stated that the decline was a result of overfishing, pollution and other environmental factors that were reducing the population of fisheries at the same time as their ecosystems were being annihilated. Many countries, such as Tonga, the United States, Australia and Bahamas, and international management bodies have taken steps to appropriately manage marine resources.

Reefs are also being destroyed by overfishing because of the huge nets that are dragged along the ocean floor while trawling. Many corals are being destroyed and, as a consequence, the ecological niche of many species is at stake.

Some fishing techniques cause habitat destruction. Blast fishing and cyanide fishing, which are illegal in many places, harm surrounding habitats. Blast fishing refers to the practice of using explosives to capture fish. Cyanide fishing refers to the practice of using cyanide to stun fish for collection. These two practices are commonly used for the aquarium trade and the live fish food trade. These practices are destructive because they impact the habitat that the reef fish live on after the fish have been removed. Bottom trawling, the practice of pulling a fishing net along the sea bottom behind trawlers, removes around 5 to 25% of an area's seabed life on a single run. This method of fishing tends to cause a lot of bycatch. A study of La Fonera Canyon compared trawled versus non-trawled areas. The results show that areas at 500 to 2000 meters depth that is non-trawled have more biodiversity, biomass, and variation of meiofauna than trawled areas at 500 meters depth. Most of the impacts are due to commercial fishing practices. A 2005 report of the UN Millennium Project, commissioned by UN Secretary-General Kofi Annan, recommended the elimination of bottom trawling on the high seas by 2006 to protect seamounts and other ecologically sensitive habitats. This was not done.

In mid-October 2006, United States President George W. Bush joined other world leaders calling for a moratorium on deep-sea trawling. The practice has shown to often have harmful effects on sea habitat and, hence, on fish populations, yet no further action was taken (Vivek). The sea animal's aquatic ecosystem may also collapse due to the destruction of the food chain.

Additionally, ghost fishing is a major threat due to capture fisheries. Ghost fishing occurs when a net, such as a gill net or trawl, is lost or discarded at sea and drifts within the oceans, and can still act to capture marine organisms. According to the Food and Agriculture Organization's 1995 Code of Conduct for Responsible Fisheries, member states should act to minimize the amount of lost and abandoned gear and work to minimize ghost fishing.

Overfishing is the removal of aquatic animals — primarily fish — from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stocks), resulting in the species becoming increasingly underpopulated in that area. Excessive fishing practices can occur in water bodies of any sizes, from ponds, wetlands, rivers, lakes to seas and oceans, and can result in resource depletion, reduced biological growth rates and low biomass levels. Sustained overfishing, especially industrial-scale commercial fishing, can lead to critical depensation, where the fish population is no longer able to sustain itself, resulting in extirpation or even extinction of species. Some forms of overfishing, such as the overfishing of sharks, has led to the upset of entire marine ecosystems. Types of overfishing include growth overfishing, recruitment overfishing, and ecosystem overfishing. Overfishing not only causes negative impacts on biodiversity and ecosystem functioning, but also reduces fish production, which subsequently leads to negative social and economic consequences.