Wild fisheries are natural bodies of water with a sizeable free-ranging fish or other aquatic animal (crustaceans and molluscs) population that can be harvested for commercial value. Wild fisheries can be marine (saltwater) or lacustrine/riverine (freshwater), and rely heavily on the carrying capacity of the local aquatic ecosystem.
Wild fisheries are sometimes called capture fisheries. The aquatic life they support is not artificially controlled in any meaningful way and needs to be "captured" or fished. Wild fisheries exist primarily in the oceans, and particularly around coasts and continental shelves, but also exist in lakes and rivers. Significant wild fisheries have collapsed or are in danger of collapsing, due to the issues of overfishing and pollution.
Overview
The global commercial production for human use of fish and other aquatic organisms occurs in two ways: they are either captured wild by commercial fishing or they are farmed using aquaculture and other fish farming techniques. As a contrast to wild fisheries, farmed fisheries can operate in sheltered coastal waters, rivers, lakes and ponds, or in enclosed bodies of water such as pools or fish tanks. Farmed fisheries are technological in nature, and revolve around developments in aquaculture. While farmed fisheries are expanding, the majority of fish consumed by humans continues to be sourced from wild fisheries. As of the early 21st century, fish is humanity's only significant wild food source.
According to the Food and Agriculture Organization (FAO), the world harvest by commercial fishing in 2010 consisted of 88.6 million tonnes of aquatic animals captured in wild fisheries, plus another 0.9 million tonnes of aquatic plants (such as seaweed). This can be contrasted with 59.9 million tonnes produced in fish farms, plus another 19.0 million tonnes of aquatic plants harvested in aquaculture.Based on data sourced from the FishStat database
In 2024, FAO found that China accounted for 14% of global capture production, and was followed by Indonesia (8%), India (7%), Peru (6%) and the Russia (5%). These five countries accounted for 41% of the total. Marine capture fisheries accounted for 87% and inland fisheries for 13% of global capture fisheries production of aquatic animals. World marine fisheries landed about 80 million tonnes of aquatic animals, an increase of 0.7% compared to the average of the previous three years, but below the peak of 84 million tonnes recorded in 2018. Finfish accounted for about 85% of total marine capture production of aquatic animals, led by anchovy, followed by alaska pollock and skipjack tuna.
Marine fisheries
The productivity of marine fisheries is largely determined by marine topography, including its interaction with ocean currents and the diminishment of sunlight with depth.
Oceanic gyres are large-scale ocean currents caused by the Coriolis effect. Wind-driven surface currents interact with these gyres and the underwater topography, such as seamounts and the edge of continental shelves, to produce downwellings and upwellings.Wind Driven Surface Currents: Upwelling and Downwelling These can transport nutrients and provide feeding grounds for plankton eating forage fish. This in turn draws larger fish that prey on the forage fish, and can result in productive fishing grounds. Most upwellings are coastal, and many of them support some of the most productive fisheries in the world, such as small pelagics (sardines, anchovies, etc.). Regions of upwelling include coastal Peru, Chile, Arabian Sea, western South Africa, eastern New Zealand and the California coast.
Continental shelves are the extended perimeters of each continent and associated coastal plain, and are important fishing areas. The shallowest parts of the continental shelf are called fishing banks.Fishing bank (2008) In Encyclopædia Britannica. Retrieved July 26, 2008, from Encyclopædia Britannica Online These waters are rich in fish resources due to the high number of plankton, on which most fish feed. Combined with the sunlight available in shallow waters, the continental shelves teem with life compared to the biotic desert of the oceans' abyssal plain. Many pelagic fish migrate across these plains in search of spawning or different feeding grounds. Smaller migratory fish are followed by larger predator fish and can provide rich, if temporary, fishing grounds.
Ocean currents The Humboldt Current (Peru Current) produces a cold, low-salinity ocean current that flows north-westward along the west coast of South America from the southern tip of Chile to northern Peru. This results in the most prominent upwelling system in the world, supporting an extraordinary abundance of marine life. Upwelling occurs off Peru year-round and off Chile during the spring and summer. A signigicant amount of the world's fish catch comes from the Humboldt Current, which includes sardines, anchovies and jack mackerel among others.
The California Current is a Pacific Ocean current that moves south along the western coast of North America, beginning off southern British Columbia, and ending off southern Baja California. The cold water of this current is highly productive due to the upwelling, which brings to the surface nutrient-rich sediments, supporting large populations of whales, seabirds and important fisheries. During El Niño events, the California Current is disrupted, leading to declines in phytoplankton, resulting in cascading effects up the food chain, such as declines in fisheries, seabird breeding failures and marine mammal mortality. In 2005, a failure in the otherwise predictable upwelling events, unassociated with El Niño, caused a collapse in krill in the current, leading to similar effects.Carina Stanton. Warmer oceans may be killing West Coast marine life. Seattle Times. 13 July 2005. Retrieved 22 March 2008.
Coral reefs Coral reefs are valuable fishing areas as they are home to a variety of tropical or reef fish, such as parrotfish, angelfish, damselfish, and butterflyfish. Other fish groups found on coral reefs include groupers, snappers, grunts and wrasses. Over 4,000 species of fish inhabit coral reefs.Spalding, Mark, Corinna Ravilious, and Edmund Green. 2001. World Atlas of Coral Reefs. Berkeley, CA: University of California Press and UNEP/WCMC.
Human activity represents the greatest threat to coral reefs around the world. In particular, marine pollution and overfishing are the most serious threats to these ecosystems. Physical destruction of reefs due to boat and shipping traffic is a major concern. The live fish trade has been implicated as a major driver of decline of coral reefs. Hughes, et al., (2003), writes that "with increased human population and improved storage and transport systems, the scale of human impacts on reefs has grown exponentially. For example, markets for fishes and other natural resources have become global, supplying demand for reef resources far removed from their tropical sources."Hughes, et al. 2003. Climate Change, Human Impacts, and the Resilience of Coral Reefs. Science. Vol 301 15 August 2003
Southeast Asian coral reefs are at risk from damaging fishing practices (such as cyanide fishing and blast fishing), overfishing, and pollution. A variety of activities, including education, regulation, and the establishment of marine protected areas are under way to protect these reefs. Indonesia, for example, has nearly of coral reefs. Its waters are home to a third of the world's total corals and a quarter of its fish species. These coral reefs are located in the heart of the Coral Triangle and have been victim to destructive fishing, unregulated tourism, and coral bleaching due to climate change. Coral bleaching in turn leads to bioerosion which threatens marine life on a significant scale.
General estimates show approximately 10% of the coral reefs around the world are already dead.Save Our Seas, 1997 Summer Newsletter, Dr. Cindy Hunter and Dr. Alan FriedlanderTun, K., L.M. Chou, A. Cabanban, V.S. Tuan, Philreefs, T. Yeemin, Suharsono, K.Sour, and D. Lane, 2004, p:235-276 in C. Wilkinson (ed.), Status of Coral Reefs of the world: 2004. It is estimated that about 60% of the world's reefs are at risk due to destructive human-related activities. The threat to the health of reefs is particularly strong in Southeast Asia, where an enormous 80% of reefs are considered endangered. Problems range from environmental impact of fishing techniques to ocean acidification.Kleypas, J.A., R.A. Feely, V.J. Fabry, C. Langdon, C.L. Sabine, and L.L. Robbins, 2006, Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: A guide for Future Research, NSF, NOAA, & USGS, 88 pp.
Inhabitants of Ahus Island, Papua New Guinea, have followed a generations-old practice of restricting fishing in six areas of their reef lagoon. While line fishing is permitted, net and spearfishing are restricted based on cultural traditions. The result is that both the biomass and individual fish sizes are significantly larger in these areas than in places where fishing is completely unrestricted.Cinner, J. et al. (2005). Conservation and community benefits from traditional coral reef management at Ahus Island, Papua New Guinea. Conservation Biology 19 (6), 1714–1723
Seamounts
A seamount is an underwater mountain, rising from the seafloor that does not reach to the water's surface (sea level). Seamounts are hotspots of marine life.Morato, Telmo. Seamounts – hotspots of marine life. ICES. Retrieved 19 June 2008.
Seamounts often project upwards into shallower zones more hospitable to marine life, providing habitats for marine species that are not found on or around the surrounding deeper ocean bottom. In addition to simply providing physical presence in this zone, the seamount itself may deflect deep currents and create upwelling. This process can bring nutrients into the photosynthetic zone, producing an area of activity in an otherwise desert-like open ocean. Seamounts may thus be vital stopping points for some migratory marine animals such as whales. Due to the larger populations of fish in these areas overexpoitation by the fishing industry has caused some seamount fauna populations to decrease considerably.
The primary productivity of the epipelagic waters above the submerged peak can often be enhanced by the hydrographic conditions of the seamount.Boehlert, G. W. and Genin, A. 1987. A review of the effects of seamounts on biological processes. 319-334. Seamount, islands and atolls. Geophysical Monograph 43, edited by B. H. Keating, P. Fryer, R. Batiza, and G. W. Boehlert. This increases the densities of the zooplankton and leads to the high concentrations of fish in these areas. Another theory for this is that the fish are sustained on the diurnal migration of zooplankton being interrupted by the presence of the seamount, and causing the zooplankton to stay in the area. It is also possible that the high densities of fishes has more to do with the fish life histories and interaction with the benthic fauna of the seamount.
During the 1960s, Russia, Australia and New Zealand started to look for new stocks of fish and began to trawl their neighboring seamounts. The majority of the invertebrates brought up are corals, and are mainly used for the jewelry trade. The two major fish species were the orange roughy (Hoplostethus atlanticus) and pelagic armourhead (Pseudopentaceros wheeleri), which were quickly overexploited due to lack of knowledge of the longevity of the fish, late maturity, low fecundity, small geographic range and recruitment to the fishery. As well as the fishes being overexploited, the benthic communities were destroyed by the trawling gear.Black, Richard (2004) Deep-sea trawling's great harm BBC.
Freshwater fisheries