Overfishing

Overfishing is the removal of a species of fish from a body of water at a rate that the species cannot replenish in time, resulting in those species either becoming depleted or very underpopulated in that given area. Overfishing has spread all over the globe and has been present for centuries.[1]

Chilean purse seine
400 tons of jack mackerel caught by a Chilean purse seiner

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.[2]

The ability of a fishery to recover from overfishing depends on whether the ecosystem's conditions are suitable for the recovery. Dramatic changes in species composition can result in an ecosystem shift, where other equilibrium energy flows involve species compositions different from those that had been present before the depletion of the original fish stock. For example, once trout have been overfished, carp might take over in a way that makes it impossible for the trout to re-establish a breeding population.

Global scale

Overfishing has stripped many fisheries around the world of their stocks. The United Nations Food and Agriculture Organization estimated in a 2018 report that 33.1% of world fish stocks are subject to overfishing.[3] Significant overfishing has been observed in pre-industrial times. In particular, the overfishing of the western Atlantic Ocean from the earliest days of European colonisation of the Americas has been well documented.[4]

The fraction of fish stocks that are within biologically sustainable levels has exhibited a decreasing trend, from 90.0 percent in 1974 to 66.9 percent in 2015. In contrast, the percentage of stocks fished at biologically unsustainable levels increased from 10 percent in 1974 to 33.1 percent in 2015, with the largest increases in the late 1970s and 1980s.

In 2015, maximally sustainably fished stocks (formerly termed fully fished stocks) accounted for 59.9 percent and underfished stocks for 7.0 percent of the total assessed stocks.[5] While the proportion of underfished stocks decreased continuously from 1974 to 2015, the maximally sustainably fished stocks decreased from 1974 to 1989, and then increased to 59.9 percent in 2015.[5]

In 2015, among the 16 major statistical areas, the Mediterranean and Black Sea had the highest percentage (62.2 percent) of unsustainable stocks, closely followed by the Southeast Pacific 61.5 percent and Southwest Atlantic 58.8 percent. In contrast, the Eastern Central Pacific, Northeast Pacific (Area 67), Northwest Pacific (Area 61), Western Central Pacific and Southwest Pacific had the lowest proportion (13 to 17 percent) of fish stocks at biologically unsustainable levels.[5]

Daniel Pauly, a fisheries scientist known for pioneering work on the human impacts on global fisheries, has commented:[6]

It is almost as though we use our military to fight the animals in the ocean. We are gradually winning this war to exterminate them. And to see this destruction happen, for nothing really – for no reason – that is a bit frustrating. Strangely enough, these effects are all reversible, all the animals that have disappeared would reappear, all the animals that were small would grow, all the relationships that you can't see any more would re-establish themselves, and the system would re-emerge.

Examples

Examples of overfishing exist in areas such as the North Sea, the Grand Banks of Newfoundland and the East China Sea.[7] In these locations, overfishing has not only proved disastrous to fish stocks but also to the fishing communities relying on the harvest. Like other extractive industries such as forestry and hunting, fisheries are susceptible to economic interaction between ownership or stewardship and sustainability, otherwise known as the tragedy of the commons.

Overfished US stocks 2015
Overfished US stocks, 2015
  • The Peruvian coastal anchovy fisheries crashed in the 1970s after overfishing and an El Niño season[8] largely depleted anchovies from its waters.[9][10] Anchovies were a major natural resource in Peru; indeed, 1971 alone yielded 10.2 million metric tons of anchovies. However, the following five years saw the Peruvian fleet's catch amount to only about 4 million tons.[8] This was a major loss to Peru's economy.
  • The sole fisheries in the Irish Sea, the west English Channel, and other locations have become overfished to the point of virtual collapse, according to the UK government's official Biodiversity Action Plan. The United Kingdom has created elements within this plan to attempt to restore this fishery, but the expanding global human population and the expanding demand for fish has reached a point where demand for food threatens the stability of these fisheries, if not the species' survival.[13]
  • Many deep sea fish are at risk, such as orange roughy and sablefish. The deep sea is almost completely dark, near freezing and has little food. Deep sea fish grow slowly because of limited food, have slow metabolisms, low reproductive rates, and many don't reach breeding maturity for 30 to 40 years. A fillet of orange roughy at the store is probably at least 50 years old. Most deep sea fish are in international waters, where there are no legal protections. Most of these fish are caught by deep trawlers near seamounts, where they congregate because of food. Flash freezing allows the trawlers to work for days at a time, and modern fishfinders target the fish with ease.[14]
  • Blue walleye became extinct in the Great Lakes in the 1980s. Until the middle of the 20th century, it was a commercially valuable fish, with about a half million tonnes being landed during the period from about 1880 to the late 1950s, when the populations collapsed, apparently through a combination of overfishing, anthropogenic eutrophication, and competition with the introduced rainbow smelt.
  • The World Wide Fund for Nature and the Zoological Society of London jointly issued their "Living Blue Planet Report" on 16 September 2015 which states that there was a dramatic fall of 74% in worldwide stocks of the important scombridae fish such as mackerel, tuna and bonitos between 1970 and 2010, and the global overall "population sizes of mammals, birds, reptiles, amphibians and fish fell by half on average in just 40 years."[15]

In management

Several countries are now effectively managing their fisheries. Examples include Iceland and New Zealand.[16] The United States has turned many of its fisheries around from being in a highly depleted state.[17]

Consequences

Surexploitation morue surpêcheEn
Atlantic cod stocks were severely overfished in the 1970s and 1980s, leading to their abrupt collapse in 1992

According to a 2008 UN report, the world's fishing fleets are losing US$50 billion each year through depleted stocks and poor fisheries management. The report, produced jointly by the World Bank and the UN Food and Agriculture Organization (FAO), asserts that half the world's fishing fleet could be scrapped with no change in catch. In addition, the biomass of global fish stocks have been allowed to run down to the point where it is no longer possible to catch the amount of fish that could be caught.[18] Increased incidence of schistosomiasis in Africa has been linked to declines of fish species that eat the snails carrying the disease-causing parasites.[19] Massive growth of jellyfish populations threaten fish stocks, as they compete with fish for food, eat fish eggs, and poison or swarm fish, and can survive in oxygen depleted environments where fish cannot; they wreak massive havoc on commercial fisheries. Overfishing eliminates a major jellyfish competitor and predator exacerbating the jellyfish population explosion.[20] Both climate change and a restructuring of the ecosystem have been found to be major roles in an increase in jellyfish population in the Irish Sea in the 1990s.[21]

Types

There are three recognized types of biological overfishing: growth overfishing, recruit overfishing and ecosystem overfishing.

Growth

Growth overfishing occurs when fish are harvested at an average size that is smaller than the size that would produce the maximum yield per recruit. A recruit is an individual that makes it to maturity, or into the limits specified by a fishery, which are usually size or age.[22] This makes the total yield less than it would be if the fish were allowed to grow to an appropriate size. It can be countered by reducing fishing mortality to lower levels and increasing the average size of harvested fish to a size that will allow maximum yield per recruit.[23][24]

Recruitment

Recruitment overfishing occurs when the mature adult population (spawning biomass) is depleted to a level where it no longer has the reproductive capacity to replenish itself—there are not enough adults to produce offspring.[23] Increasing the spawning stock biomass to a target level is the approach taken by managers to restore an overfished population to sustainable levels. This is generally accomplished by placing moratoriums, quotas and minimum size limits on a fish population.

Ecosystem

Ecosystem overfishing occurs when the balance of the ecosystem is altered by overfishing. With declines in the abundance of large predatory species, the abundance of small forage type increases causing a shift in the balance of the ecosystem towards smaller fish species.

Acceptable levels

The notion of overfishing hinges on what is meant by an acceptable level of fishing. More precise biological and bioeconomic terms define acceptable level as follows:

  • Biological overfishing occurs when fishing mortality has reached a level where the stock biomass has negative marginal growth (reduced rate of biomass growth), as indicated by the red area in the figure. (Fish are being taken out of the water so quickly that the replenishment of stock by breeding slows down. If the replenishment continues to diminish for long enough, replenishment will go into reverse and the population will decrease.)[25]
  • Economic or bioeconomic overfishing additionally considers the cost of fishing when determining acceptable catches. Under this framework, a fishery is considered to be overfished when catches exceed maximum economic yield where resource rent is at its maximum. Fish are being removed from the fishery so quickly that the profitability of the fishery is sub-optimal. A more dynamic definition of economic overfishing also considers the present value of the fishery using a relevant discount rate to maximise the flow of resource rent over all future catches.
Harvest Control Rule graph
The Traffic Light colour convention, showing the concept of Harvest Control Rule (HCR), specifying when a rebuilding plan is mandatory in terms of precautionary and limit reference points for spawning biomass and fishing mortality rate.

Harvest control rule

A model proposed in 2010 for predicting acceptable levels of fishing is the Harvest Control Rule (HCR),[26] which is a set of tools and protocols with which management has some direct control of harvest rates and strategies in relation to predicting stock status, and long-term maximum sustainable yields. Constant catch and constant fishing mortality are two types of simple harvest control rules.[27]

Input and output orientations

Fishing capacity can also be defined using an input or output orientation.

  • An input-oriented fishing capacity is defined as the maximum available capital stock in a fishery that is fully utilized at the maximum technical efficiency in a given time period, given resource and market conditions.[28]
  • An output-oriented fishing capacity is defined as the maximum catch a vessel (fleet) can produce if inputs are fully utilized given the biomass, the fixed inputs, the age structure of the fish stock, and the present stage of technology.[29]

Technical efficiency of each vessel of the fleet is assumed necessary to attain this maximum catch. The degree of capacity utilization results from the comparison of the actual level of output (input) and the capacity output (input) of a vessel or a fleet.

Mitigation

In order to meet the problems of overfishing, a precautionary approach and Harvest Control Rule (HCR) management principles have been introduced in the main fisheries around the world. The Traffic Light color convention introduces sets of rules based on predefined critical values, which could be adjusted as more information is gained.

The United Nations Convention on the Law of the Sea treaty deals with aspects of over fishing in articles 61, 62, and 65.[30]

  • Article 61 requires all coastal states to ensure that the maintenance of living resources in their exclusive economic zones is not endangered by over-exploitation. The same article addresses the maintenance or restoration of populations of species above levels at which their reproduction may become seriously threatened.
  • Article 62 provides that coastal states: "shall promote the objective of optimum utilization of the living resources in the exclusive economic zone without prejudice to Article 61"
  • Article 65 provides generally for the rights of, inter alia, coastal states to prohibit, limit, or regulate the exploitation of marine mammals.

According to some observers, overfishing can be viewed as an example of the tragedy of the commons; appropriate solutions would therefore promote property rights through, for instance, privatization and fish farming. Daniel K. Benjamin, in Fisheries are Classic Example of the "Tragedy of the Commons", cites research by Grafton, Squires and Fox to support the idea that privatization can solve the overfishing problem:[31]

According to recent research on the British Columbia halibut fishery, where the commons has been at least partly privatized, substantial ecological and economic benefits have resulted. There is less damage to fish stocks, the fishing is safer, and fewer resources are needed to achieve a given harvest.

Another possible solution, at least for some areas, is quotas, so fishermen can only legally take a certain amount of fish. A more radical possibility is declaring certain areas of the sea "no-go zones" and make fishing there strictly illegal, so the fish in that area have time to recover and repopulate.

In order to maximise resources some countries (e.g. Bangladesh and Thailand) have improved the availability of family planning services. The resulting smaller populations have a decreased environmental footprint and less food needs to provided.[32]

Controlling consumer behavior and demand is critical in mitigating action. Worldwide, a number of initiatives emerged to provide consumers with information regarding the conservation status of the seafood available to them. The Guide to Good Fish Guides lists a number of these.

Government regulation

Many regulatory measures are available for controlling overfishing. These measures include fishing quotas, bag limits, licensing, closed seasons, size limits and the creation of marine reserves and other marine protected areas.

A model of the interaction between fish and fishers showed that when an area is closed to fishers, but there are no catch regulations such as individual transferable quotas, fish catches are temporarily increased but overall fish biomass is reduced, resulting in the opposite outcome from the one desired for fisheries.[33] Thus, a displacement of the fleet from one locality to another will generally have little effect if the same quota is taken. As a result, management measures such as temporary closures or establishing a marine protected area of fishing areas are ineffective when not combined with individual fishing quotas. An inherent problem with quotas is that fish populations vary from year to year. A study has found that fish populations rise dramatically after stormy years due to more nutrients reaching the surface and therefore greater primary production.[34] To fish sustainably, quotas need to be changed each year to account for fish population.

Individual transferable quotas (ITQs) are fishery rationalization instruments defined under the Magnuson-Stevens Fishery Conservation and Management Act as limited access permits to harvest quantities of fish. Fisheries scientists decide the optimal amount of fish (total allowable catch) to be harvested in a certain fishery. The decision considers carrying capacity, regeneration rates and future values. Under ITQs, members of a fishery are granted rights to a percentage of the total allowable catch that can be harvested each year. These quotas can be fished, bought, sold, or leased allowing for the least cost vessels to be used. ITQs are used in New Zealand, Australia, Iceland, Canada, and the United States.

In 2008, a large-scale study of fisheries that used ITQs compared to ones that didn't provided strong evidence that ITQs can help to prevent collapses and restore fisheries that appear to be in decline.[35][36][37][38]

China bans fishing in the South China Sea for a period each year.[39]

Removal of subsidies

Several scientists have called for an end to subsidies paid to deep sea fisheries. In international waters beyond the 200 nautical mile exclusive economic zones of coastal countries, many fisheries are unregulated, and fishing fleets plunder the depths with state-of-the-art technology. In a few hours, massive nets weighing up to 15 tons, dragged along the bottom by deep-water trawlers, can destroy deep-sea corals and sponge beds that have taken centuries or millennia to grow. The trawlers can target orange roughy, grenadiers, or sharks. These fish are usually long-lived and late maturing, and their populations take decades, even centuries to recover.[40]

Fisheries scientist Daniel Pauly and economist Ussif Rashid Sumaila have examined subsidies paid to bottom trawl fleets around the world. They found that US$152 million per year are paid to deep-sea fisheries. Without these subsidies, global deep-sea fisheries would operate at a loss of $50 million a year. A great deal of the subsidies paid to deep-sea trawlers is to subsidize the large amount of fuel required to travel beyond the 200-mile limit and drag weighted nets.[40]

"There is surely a better way for governments to spend money than by paying subsidies to a fleet that burns 1.1 billion litres of fuel annually to maintain paltry catches of old growth fish from highly vulnerable stocks, while destroying their habitat in the process" – Pauly.[40]

"Eliminating global subsidies would render these fleets economically unviable and would relieve tremendous pressure on over-fishing and vulnerable deep-sea ecosystems" – Sumaila.[40]

Minimizing fishing impact

Fishing techniques may be altered to minimize bycatch and reduce impacts on marine habitats. These techniques include using varied gear types depending on target species and habitat type. For example, a net with larger holes will allow undersized fish to avoid capture. A turtle excluder device (TED) allows sea turtles and other megafauna to escape from shrimp trawls. Avoiding fishing in spawning grounds may allow fish stocks to rebuild by giving adults a chance to reproduce.

Aquaculture

Global total fish harvest.svg&lang=en
Global harvest of aquatic organisms in million tonnes, 1950–2010, as reported by the FAO.

Aquaculture involves the farming of fish in captivity. This approach effectively privatizes fish stocks and creates incentives for farmers to conserve their stocks. It also reduces environmental impact. However, farming carnivorous fish, such as salmon, does not always reduce pressure on wild fisheries, since carnivorous farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish.

Aquaculture played a minor role in the harvesting of marine organisms until the 1970s. Growth in aquaculture increased rapidly in 1990s when the rate of wild capture plateaued. Aquaculture now provides approximately half of all harvested aquatic organisms. Aquaculture production rates continue to grow while wild harvest remains steady.

Fish farming can enclose the entire breeding cycle of the fish, with fish being bred in captivity. Some fish prove difficult to breed in captivity and can be caught in the wild as juveniles and brought into captivity to increase their weight. With scientific progress more species are being made to breed in captivity. This was the case with southern bluefin tuna, which were first bred in captivity in 2009.[41]

Consumer awareness

Sustainable seafood is a movement that has gained momentum as more people become aware of overfishing and environmentally destructive fishing methods. Sustainable seafood is seafood from either fished or farmed sources that can maintain or increase production in the future without jeopardizing the ecosystems from which it was acquired. In general, slow-growing fish that reproduce late in life, such as orange roughy, are vulnerable to overfishing. Seafood species that grow quickly and breed young, such as anchovies and sardines, are much more resistant to overfishing. Several organizations, including the Marine Stewardship Council (MSC), and Friend of the Sea, certify seafood fisheries as sustainable.

The Marine Stewardship Council has developed an environmental standard for sustainable and well-managed fisheries. Environmentally responsible fisheries management and practices are rewarded with the use of its blue product ecolabel. Consumers concerned about overfishing and its consequences are increasingly able to choose seafood products that have been independently assessed against the MSC's environmental standard. This enables consumers to play a part in reversing the decline of fish stocks. As of February 2012, over 100 fisheries around the world have been independently assessed and certified as meeting the MSC standard. Their where-to-buy page lists the currently available certified seafood. As of February 2012 over 13,000 MSC-labelled products are available in 74 countries around the world. Fish & Kids is an MSC project to teach schoolchildren about marine environmental issues, including overfishing.

The Monterey Bay Aquarium's Seafood Watch Program, although not an official certifying body like the MSC, also provides guidance on the sustainability of certain fish species.[42] Some seafood restaurants have begun to offer more sustainable seafood options. The Seafood Choices Alliance[43] is an organization whose members include chefs that serve sustainable seafood at their establishments. In the US, the Sustainable Fisheries Act defines sustainable practices through national standards. Although there is no official certifying body like the MSC, the National Oceanic and Atmospheric Administration has created FishWatch to help guide concerned consumers to sustainable seafood choices. See also a guide to good fish guides.

In September 2016, a partnership of Google and Oceana and Skytruth introduced Global Fishing Watch, a website designed to assist citizens of the globe in monitoring fishing activities.[44][45][46]

Barriers to effective management

The fishing industry has a strong financial incentive to oppose some measures aimed at improving the sustainability of fish stocks.[4] Recreational fisherman also have an interest in maintaining access to fish stocks. This leads to extensive lobbying that can block or water down government policies intended to prevent overfishing.

Outside of countries' exclusive economic zones, fishing is difficult to control. Large oceangoing fishing boats are free to exploit fish stocks at will.

In waters that are the subject of territorial disputes, countries may actively encourage overfishing. A notable example is the cod wars where Britain used its navy to protect its trawlers fishing in Iceland's exclusive economic zone. Fish are highly transitory. Many species will freely move through different jurisdictions. The conservation efforts of one country can then be exploited by another.

While governments can create regulations to control people's behaviours this can be undermined by illegal fishing activity. Estimates of the size of the illegal catch range from 11 to 26 million tonnes, which represents 14-33% of the world's reported catch.[47] Illegal fishing can take many forms. In some developing countries, large numbers of poor people are dependent on fishing. It can prove difficult to regulate this kind of overfishing, especially for weak governments. Even in regulated environments, illegal fishing may occur. While industrial fishing is often effectively controlled, smaller scale and recreational fishermen can often break regulations such as bag limits and seasonal closures. Fisherman can also easily fish illegally by doing things such as underreporting the amount of fish they caught or reporting that they caught one type of fish while actually catching another.[48] There is also a large problem with surveillance of illegal fishing activity. In 2001, the UN Food and Agriculture Organization (FAO), passed the International Plan of Action to Prevent, Deter and Eliminate Illegal, Unreported and Unregulated Fishing (IPOA-IUU). This is an agreement with the intention to stop port states from allowing boats to dock that participated in illegal, unreported or unregulated fishing. It also gives details for port states on effective measures of inspecting and reporting illegal fishing.[49] Some illegal fishing takes place on an industrial scale with financed commercial operations.

The fishing capacity problem is not only related to the conservation of fish stocks but also to the sustainability of fishing activity. Causes of the fishing problem can be found in the property rights regime of fishing resources. Overexploitation and rent dissipation of fishermen arise in open-access fisheries as was shown in Gordon.[50][51]

In open-access resources like fish stocks, in the absence of a system like individual transferable quotas, the impossibility of excluding others provokes the fishermen who want to increase catch to do so effectively by taking someone else' share, intensifying competition. This tragedy of the commons provokes a capitalization process that leads them to increase their costs until they are equal to their revenue, dissipating their rent completely.

Resistance from fishermen

There is always disagreement between fishermen and government scientists... Imagine an overfished area of the sea in the shape of a hockey field with nets at either end. The few fish left therein would gather around the goals because fish like structured habitats. Scientists would survey the entire field, make lots of unsuccessful hauls, and conclude that it contains few fish. The fishermen would make a beeline to the goals, catch the fish around them, and say the scientists do not know what they are talking about. The subjective impression the fishermen get is always that there's lots of fish - because they only go to places that still have them... fisheries scientists survey and compare entire areas, not only the productive fishing spots.[52]Fisheries scientist Daniel Pauly

See also

References

Citations

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Sources

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Bibliography

External links

External image
Biomass distributions for high trophic-level fishes in the North Atlantic, 1900–2000 Flash animation from The Sea Around Us
Ecological resilience

In ecology, resilience is the capacity of an ecosystem to respond to a perturbation or disturbance by resisting damage and recovering quickly. Such perturbations and disturbances can include stochastic events such as fires, flooding, windstorms, insect population explosions, and human activities such as deforestation, fracking of the ground for oil extraction, pesticide sprayed in soil, and the introduction of exotic plant or animal species. Disturbances of sufficient magnitude or duration can profoundly affect an ecosystem and may force an ecosystem to reach a threshold beyond which a different regime of processes and structures predominates. Human activities that adversely affect ecosystem resilience such as reduction of biodiversity, exploitation of natural resources, pollution, land use, and anthropogenic climate change are increasingly causing regime shifts in ecosystems, often to less desirable and degraded conditions. Interdisciplinary discourse on resilience now includes consideration of the interactions of humans and ecosystems via socio-ecological systems, and the need for shift from the maximum sustainable yield paradigm to environmental resource management which aims to build ecological resilience through "resilience analysis, adaptive resource management, and adaptive governance".

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 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. There is a growing gap between the supply of fish and demand, due in part to world population growth.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. Yet again the analysis has met criticism as being fundamentally flawed, and many fishery management officials, industry representatives and scientists challenge the findings, although the debate continues. 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.

Estuary

An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.Estuaries form a transition zone between river environments and maritime environments. They are subject both to marine influences—such as tides, waves, and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The mixing of seawater and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays, harbors, lagoons, inlets, or sounds, although some of these water bodies do not strictly meet the above definition of an estuary and may be fully saline.

The banks of many estuaries are amongst the most heavily populated areas of the world, with about 60% of the world's population living along estuaries and the coast. As a result, many estuaries suffer degradation from a variety of factors including: sedimentation from soil erosion from deforestation, overgrazing, and other poor farming practices; overfishing; drainage and filling of wetlands; eutrophication due to excessive nutrients from sewage and animal wastes; pollutants including heavy metals, polychlorinated biphenyls, radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion.

Factory ship

A factory ship, also known as a fish processing vessel, is a large ocean-going vessel with extensive on-board facilities for processing and freezing caught fish or whales. Modern factory ships are automated and enlarged versions of the earlier whalers and their use for fishing has grown dramatically. Some factory ships are equipped to serve as a mother ship.

Fishery

Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats, purpose of the activities or a combination of the foregoing features". The definition often includes a combination of fish and fishers in a region, the latter fishing for similar species with similar gear types.A fishery may involve the capture of wild fish or raising fish through fish farming or aquaculture. Directly or indirectly, the livelihood of over 500 million people in developing countries depends on fisheries and aquaculture. Overfishing, including the taking of fish beyond sustainable levels, is reducing fish stocks and employment in many world regions. A report by Prince Charles' International Sustainability Unit, the New York-based Environmental Defence Fund and 50in10 published in July 2014 estimated global fisheries were adding $270 billion a year to global GDP, but by full implementation of sustainable fishing, that figure could rise by as much as $50 billion.

Fishing in India

Fishing in India is a major industry in its coastal states, employing over 14 million people. In 2016-17, the country exported 11,34,948 metric tonnes of seafood worth US$ 5.78 billion (₹37,870.90 crore), frozen shrimp being the top item of export. According to the Food and Agriculture Organization (FAO) of the United Nations, fish production has increased more than tenfold since 1947 and doubled between 1990 and 2010.India has 8,129 kilometres (5,051 mi) of marine coastline, 3,827 fishing villages and 1,914 traditional fish landing centers. India's fresh water resources consist of 195,210 kilometres (121,300 mi) of rivers and canals, 2.9 million hectares of minor and major reservoirs, 2.4 million hectares of ponds and lakes, and about 0.8 million hectares of flood plain wetlands and water bodies. As of 2010, the marine and freshwater resources offered a combined sustainable catch fishing potential of over 4 million metric tonnes of fish. In addition, India's water and natural resources offer a tenfold growth potential in aquaculture (farm fishing) from 2010 harvest levels of 3.9 million metric tonnes of fish, if India were to adopt fishing knowledge, regulatory reforms and sustainability policies.

Fishing in the North Sea

Fishing in the North Sea is concentrated in the southern part of the coastal waters. The main method of fishing is trawling.

Annual catches grew each year until the 1980s, when a high point of more than 3 million metric tons (3.3 million S/T) was reached. Since then, the numbers have fallen back to around 2.3 million tons (2.5 million S/T) annually with considerable differences between years. Besides the fish caught, it is estimated that 150,000 metric tons (165,000 S/T) of unmarketable by-catch are caught and around 85,000 metric tons (94,000 S/T) of dead and injured invertebrates.Of the caught fish, about half are used for the production of fish oil and fish meal.

Flemish Cap

The Flemish Cap is an area of shallow waters in the north Atlantic Ocean centered roughly at 47° north, 45° west or about 563 km (350 miles) east of St. John's, Newfoundland and Labrador.

The shallow water is caused by a wide underwater plateau covering an extended area of 42,000 km² (12,000 square miles). Depths at the cap range from approximately 122 m (400 feet) to 700 m (2,300 feet).

The Flemish Cap is located within an area of transition between the cold waters of the Labrador Current and warmer waters influenced by the Gulf Stream. The mixing of the warmer and colder waters over the plateau produces the characteristic clockwise circulation current over the cap.

The waters of the Flemish Cap are deeper and warmer than the Grand Banks of Newfoundland. The 58,000-square-kilometre area may have served as an important refuge for marine species during the last ice age.The Flemish Cap lies outside Canada's 200 nautical mile (370 km) Exclusive Economic Zone established in 1977, and is therefore in international fishing waters. Overfishing has become a serious issue in recent years. Cod and American plaice are particularly endangered here and the numbers of redfish have shown a significant decline.In recent years, Canada had made an effort to prevent overfishing in the region by use of provisions of the Coastal Fisheries Protection Act and the United Nations Fish Stocks Agreement.

The origin of the Flemish Cap's name is unclear. It arguably refers to Flemish fishermen venturing out this far west in the nineteenth century.

Grand Banks of Newfoundland

The Grand Banks of Newfoundland are a group of underwater plateaus south-east of Newfoundland on the North American continental shelf. These areas are relatively shallow, ranging from 15 to 91 metres (50 to 300 ft) in depth. The cold Labrador Current mixes with the warm waters of the Gulf Stream here, often causing extreme foggy conditions.

The mixing of these waters and the shape of the ocean bottom lifts nutrients to the surface. These conditions helped to create one of the richest fishing grounds in the world. Fish species include Atlantic cod, swordfish, haddock and capelin; shellfish include scallop and lobster. The area also supports large colonies of seabirds such as northern gannets, shear waters and sea ducks and various sea mammals such as seals, dolphins and whales.

Overfishing in the late 20th century caused the collapse of several species, particularly cod, leading to the closure of the Canadian Grand Banks fishery in 1992.

Magnuson–Stevens Fishery Conservation and Management Act

The Magnuson–Stevens Fishery Conservation and Management Act (MSFCMA), commonly referred to as the Magnuson–Stevens Act (MSA), is the legal provision for promoting optimal exploitation of U.S. coastal fisheries. Enacted in 1976, it has since been amended in line with sustainability policy.

Regional councils of the National Marine Fisheries Service (NMFS) determine when a stock is overfished, and apply both regional and individual catch limits. The NMFS has implemented the Fish Stock Sustainability Index (FSSI), which measures key stocks according to their overfishing status and biomass levels.

Marine conservation activism

Marine Conservation Activism refers to the efforts of non-governmental organizations and individuals to bring about social and political change in the area of marine conservation. Marine conservation is properly conceived as a set of management strategies for the protection and preservation of ecosystems in oceans and seas. Activists raise public awareness and support for conservation, while pushing governments and corporations to practice sound ocean management, create conservation policy, and enforce existing laws and policy through effective regulation. There are many different kinds of organizations and agencies that work toward these common goals. They all are a part of the growing movement that is ocean conservation. These organizations fight for many causes including stopping pollution, overfishing, whaling, by-catching, and Marine Protected Areas.

Renewable resource

A renewable resource is a natural resource which will replenish to replace the portion depleted by usage and consumption, either through natural reproduction or other recurring processes in a finite amount of time in a human time scale. Renewable resources are a part of Earth's natural environment and the largest components of its ecosphere. A positive life cycle assessment is a key indicator of a resource's sustainability.Definitions of renewable resources may also include agricultural production, as in sustainable agriculture and to an extent water resources. In 1962, Paul Alfred Weiss defined Renewable Resources as: "The total range of living organisms providing man with life, fibres, etc...". Another type of renewable resources is renewable energy resources. Common sources of renewable energy include solar, geothermal and wind power, which are all categorised as renewable resources.

Sparidae

The Sparidae are a family of fish in the order Perciformes, commonly called sea breams and porgies. The sheepshead, scup, and red seabream are species in this family. Most sparids are deep-bodied compressed fish with a small mouth separated by a broad space from the eye, a single dorsal fin with strong spines and soft rays, a short anal fin, long pointed pectoral fins and rather large firmly attached scales. They are found in shallow temperate and tropical waters and are bottom-dwelling carnivores.

There are hermaphrodites in the Sparidae. Protogyny and protandry appear sporadically through this lineage of fish. Simultaneous hermaphrodites and bi-directional hermaphrodites do not appear as much since Sparidae are found in shallower waters. Species of fish that express a hermaphroditic condition usually "lack a genetic hardwire", therefore ecological factors play a role in sex determination.Most species possess grinding, molar-like teeth. Some of the species, such as Polysteganus undulosus, have been subject to overfishing, or exploitation beyond sustainable recovery.

Stock assessment

Stock assessments provide fisheries managers with the information that is used in the regulation of a fish stock. Biological and fisheries data are collected in a stock assessment.

A wide array of biological data may be collected for an assessment. These include details on the age structure of the stock, age at first spawning, fecundity, ratio of males to females in the stock, natural mortality (M), fishing mortality (F), growth rate of the fish, spawning behavior, critical habitats, migratory habits, food preferences, and an estimate of either the total population or total biomass of the stock.

The following data regarding fisheries activities is collected: the kinds of fisherman in the fishery, commercial versus recreational, and the gear that is used (longline, rod and reel, nets, etc.), pounds of fish caught by each type of fisherman, the fishing effort each kind of fisherman expends, the age structure of the fish harvested by each group of fisherman, the ratio of males to females that are captured, how the fish are marketed, the value of the fish to the different fisherman groups, and the time and geographic location of the best catches. Also in the assessment, geographical boundaries of different stocks or populations are defined. From the combined biological and fisheries data, the current status and condition of the stock is defined and managers use this assessment to predict how in the future, stocks will respond to varying levels of fishing pressure. Ultimately managers want to reduce the level of overfishing that occurs and restore stocks that have been overfished.

Sustainable fishery

A conventional idea of a sustainable fishery is that it is one that is harvested at a sustainable rate, where the fish population does not decline over time because of fishing practices. Sustainability in fisheries combines theoretical disciplines, such as the population dynamics of fisheries, with practical strategies, such as avoiding overfishing through techniques such as individual fishing quotas, curtailing destructive and illegal fishing practices by lobbying for appropriate law and policy, setting up protected areas, restoring collapsed fisheries, incorporating all externalities involved in harvesting marine ecosystems into fishery economics, educating stakeholders and the wider public, and developing independent certification programs.

Some primary concerns around sustainability are that heavy fishing pressures, such as overexploitation and growth or recruitment overfishing, will result in the loss of significant potential yield; that stock structure will erode to the point where it loses diversity and resilience to environmental fluctuations; that ecosystems and their economic infrastructures will cycle between collapse and recovery; with each cycle less productive than its predecessor; and that changes will occur in the trophic balance (fishing down marine food webs).

Sustainable seafood

Sustainable seafood is seafood that is either caught or farmed in ways that consider the long-term vitality of harvested species and the well-being of the oceans, as well as the livelihoods of fisheries-dependent communities. It was first promoted through the sustainable seafood movement which began in the 1990s. This operation highlights overfishing and environmentally destructive fishing methods. Through a number of initiatives, the movement has increased awareness and raised concerns over the way our seafood is obtained.

The Black Fish

The Black Fish is an international marine conservation organisation based in Amsterdam, Netherlands. The Black Fish's stated mission is to "end the industrial overfishing of the oceans" and to "empower individuals to get actively involved in building grassroots citizen-led conservation communities". The non-governmental organisation was founded in 2010 and has active local chapters in Germany, Sweden, the Netherlands, Spain the United Kingdom and most recently Finland. To achieve its goals, the organisation uses a combination of investigation, education, and non-violent direct-action. Campaigns have included gathering support for the release of captive cetaceans, actions against dolphin drive hunts and campaigning to end overfishing of the endangered bluefin tuna in the Mediterranean Sea.

The End of the Line (book)

The End of the Line: How Overfishing Is Changing the World and What We Eat is a book by journalist Charles Clover about overfishing. Clover, a former environment editor of the Daily Telegraph (London) and now a columnist on the Sunday Times (London), describes how modern fishing is destroying ocean ecosystems. He concludes that current worldwide fish consumption is unsustainable. The book provides details about overfishing in many of the world's critical ocean habitats, such as the New England fishing grounds, west African coastlines, the European North Atlantic fishing grounds, and the ocean around Japan. The book concludes with suggestions on how the nations of the world could engage in sustainable ocean fishing.

Trachurus

Jack mackerels or saurels are marine fish in the genus Trachurus of the family Carangidae. The name of the genus derives from the Greek words trachys ("rough") and oura ("tail"). Some species, such as T. murphyi, are harvested in purse seine nets, and overfishing (harvesting beyond sustainable levels) has sometimes occurred.It is often used in Japanese cuisine, where it is called aji, and in Turkish cuisine, where it is called istavrit.

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