26 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 by-catch. 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.

Aquarium fishery is the process of fishing wild fish for sale to private and public aquariums.

Introduced Asian carp in North America pose a major threat to the ecology, environment, economy, and way of life in the Upper Midwest and Great Lakes region of the United States and Canada. Asian carp are a group of fish species, which include several known to be invasive, and represent the most urgent potential danger to the ecology of the Great Lakes. The United States Department of the Interior and United States Fish and Wildlife Service presented their first annual report to Congress on the issue in December 2014.

Blast fishing, Fish Bombing, or dynamite fishing is a destructive fishing practice using explosives to stun or kill schools of fish for easy collection. This often illegal practice is extremely destructive to the surrounding ecosystem, as the explosion often destroys the underlying habitat that supports the fish. The frequently improvised nature of the explosives used means danger for the fishermen as well, with accidents and injuries.

Bottom trawling is trawling along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is towing a net at the very bottom of the ocean and demersal trawling is towing a net just above the benthic zone. Bottom trawling can be contrasted with midwater trawling, where a net is towed higher in the water column. Midwater trawling catches pelagic fish such as anchovies and mackerel, whereas bottom trawling targets both bottom-living fish (groundfish) and semi-pelagic species such as cod, squid, shrimp, and rockfish.

Bycatch, in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juveniles of the target species. The term "bycatch" is also sometimes used for untargeted catch in other forms of animal harvesting or collecting. Non-marine species that are caught but regarded as generally "undesirable" are referred to as "rough fish" and "coarse fish".

CalCOFI is a multi-agency partnership formed in 1949 to investigate the collapse of the sardine population off California. The organization's members are from NOAA Fisheries Service, Scripps Institution of Oceanography, and California Department of Fish and Wildlife. The scope of this research has evolved into the study of marine ecosystems off California and the management of its fisheries resources. In 2004, the CalCOFI survey area became one of 26 LTER research sites. This time-series of oceanographic and fisheries data allows scientists to assess the human impact and effects of climate change on the coastal ocean ecosystem. CalCOFI hydrographic & biological data, publications, and web information are distributed for use without restriction under the terms of the GNU Free Documentation License.

Cetacean bycatch is the incidental capture of non-target cetacean species such as dolphins, porpoises, and whales by fisheries. Bycatch can be caused by entanglement in fishing nets and lines, or direct capture by hooks or in trawl nets.

In 1992, Northern Cod populations fell to 1% of historical levels, due in large part to decades of overfishing. The Canadian Federal Minister of Fisheries and Oceans, John Crosbie, declared a moratorium on the Northern Cod fishery, which for the preceding 500 years had primarily shaped the lives and communities of Canada's eastern coast. A significant factor contributing to the depletion of the cod stocks off Newfoundland's shores was the introduction of equipment and technology that increased landed fish volume. From the 1950s onwards, new technology allowed fishers to trawl a larger area, fish more in-depth, and for a longer time. By the 1960s, powerful trawlers equipped with radar, electronic navigation systems, and sonar allowed crews to pursue fish with unparalleled success, and Canadian catches peaked in the late-1970s and early-1980s. Cod stocks were depleted at a faster rate than could be replenished.

Dolphin drive hunting, also called dolphin drive fishing, is a method of hunting dolphins and occasionally other small cetaceans by driving them together with boats and then usually into a bay or onto a beach. Their escape is prevented by closing off the route to the open sea or ocean with boats and nets. Dolphins are hunted this way in several places around the world, including the Solomon Islands, the Faroe Islands, Peru, and Japan, the most well-known practitioner of this method. By numbers, dolphins are mostly hunted for their meat; some end up in dolphinariums.

Drift netting is a fishing technique where nets, called drift nets, hang vertically in the water column without being anchored to the bottom. The nets are kept vertical in the water by floats attached to a rope along the top of the net and weights attached to another rope along the bottom of the net. Drift nets generally rely on the entanglement properties of loosely affixed netting. Folds of loose netting, much like a window drapery, snag on a fish's tail and fins and wrap the fish up in loose netting as it struggles to escape. However the nets can also function as gill nets if fish are captured when their gills get stuck in the net. The size of the mesh varies depending on the fish being targeted. These nets usually target schools of pelagic fish.

The End of the Line: How Overfishing Is Changing the World and What We Eat is a book by journalist Charles Clover about overfishing. It was made into a movie released in 2009 and was re-released with updates in 2017.

Salmon population levels are of concern in the Atlantic and in some parts of the Pacific. Salmon are anadromous - they rear and grow in freshwater, migrate to the ocean to reach sexual maturity, and then return to freshwater to spawn. Determining how environmental stressors and climate change will affect these fisheries is challenging due to their lives split between fresh and saltwater. Environmental variables like warming temperatures and habitat loss are detrimental to salmon abundance and survival. Other human influenced effects on salmon like overfishing and gillnets, sea lice from farm raised salmon, and competition from hatchery released salmon have negative effects as well.

Fishing down the food web is the process whereby fisheries in a given ecosystem, "having depleted the large predatory fish on top of the food web, turn to increasingly smaller species, finally ending up with previously spurned small fish and invertebrates".

Ghost nets are fishing nets that have been left or lost in the ocean by fishermen. These nets, often nearly invisible in the dim light, can be left tangled on a rocky reef or drifting in the open sea. They can entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatures, including the occasional human diver. Acting as designed, the nets restrict movement, causing starvation, laceration and infection, and suffocation in those that need to return to the surface to breathe.

Global Fishing Watch is a website launched in September 2016 by Google in partnership with Oceana and SkyTruth "to provide the world’s first global view of commercial fishing activities." At any moment, 200,000 vessels are publicizing their locations via the Automatic Identification System (AIS).

High Seas Driftnet Fisheries Enforcement Act of 1992 is United States declaration citing an observance of the United Nations international driftnet fishery conservation program to restrict large scale driftnet fishing in high seas or international waters. The Act of Congress acknowledges the United Nations General Assembly Resolutions imposing a global moratorium on all high seas driftnet fishing by December 31, 1992. In accordance with Title 16 section 1857, the United States federal law 102-582 proclaims the Magnuson–Stevens Fishery Conservation and Management Act prohibits the application of large scale driftnet fishing within an exclusive economic zone of any sovereign state and the United States.

Hotspot Ecosystem Research and Man's Impact On European Seas (HERMIONE) is an international multidisciplinary project, started in April 2009, that studies deep-sea ecosystems. HERMIONE scientists study the distribution of hotspot ecosystems, how they function and how they interconnect, partially in the context of how these ecosystems are being affected by climate change and impacted by humans through overfishing, resource extraction, seabed installations and pollution. Major aims of the project are to understand how humans are affecting the deep-sea environment and to provide policy makers with accurate scientific information, enabling effective management strategies to protect deep sea ecosystems. The HERMIONE project is funded by the European Commission's Seventh Framework Programme, and is the successor to the HERMES project, which concluded in March 2009.

Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a sea or ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping. Naturally occurring debris, such as driftwood and drift seeds, are also present.

Fish and shellfish concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organomercury compound. Fish products have been shown to contain varying amounts of heavy metals, particularly mercury and fat-soluble pollutants from water pollution. Species of fish that are long-lived and high on the food chain, such as marlin, tuna, shark, swordfish, king mackerel and tilefish contain higher concentrations of mercury than others.

Muro-Ami is a 1999 Philippine drama film directed by Marilou Diaz-Abaya. It stars Cesar Montano as Fredo, a ruthless captain of 150 muro-ami divers, who employ illegal fishing practices, such as pounding and crushing corals to scare fish, driving them towards the nets. It depicts one of the worst forms of child labor in the illegal fishing system.

Overfishing is the removal of a species of fish from a body of water at a rate that the species cannot replenish, resulting in those species becoming underpopulated in that area. Overfishing can occur in water bodies of any sizes, such as ponds, rivers, lakes or oceans, and can result in resource depletion, reduced biological growth rates and low biomass levels. Sustained overfishing can lead to critical depensation, where the fish population is no longer able to sustain itself. 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, ecosystem overfishing.

The rough scallop, Aequipecten muscosus, grows up to 1.75 in (4.4 cm). It has a small, scallop-shaped shell with about 20 strong ribs which have many erect scales or small spines near the margin. The hinge line has ears.

Shark finning is the act of removing fins from sharks and discarding the rest of the shark back into the ocean. This act is prohibited in many countries. The sharks are often still alive when discarded, but without their fins. Unable to swim effectively, they sink to the bottom of the ocean and die of suffocation or are eaten by other predators. Shark finning at sea enables fishing vessels to increase profitability and increase the number of sharks harvested, as they must only store and transport the fins, by far the most profitable part of the shark; the shark meat is bulky to transport. Some countries have banned this practice and require the whole shark to be brought back to port before removing the fins.

Unsustainable fishing methods refers to the utilization of the various fishing methods in order to capture or harvest fish at a rate which sees the declining of fish populations over time. These methods are observed to facilitate the destructive fishing practices that destroy ecosystems within the ocean, and is used as a tool for over-fishing which results in the depletion of fish populations at a rate that cannot be sustained.