Overfishing

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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.

Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans. There are more precise biological and bioeconomic definitions which say what is an 'acceptable level'.

Biological overfishing occurs when fishing mortality has reached a level where the stock biomass has negative marginal growth (slowing down 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 slow down for long enough, replenishment will go into reverse and the population will decrease.)

Economic or bioeconomic overfishing additionally considers the cost of fishing and defines overfishing as a situation of negative marginal growth of resource rent. (Fish are being taken out of the water so quickly that the growth in the profitability of fishing slows down. If this continues for long enough, profitability will decrease.)

A more dynamic definition of economic overfishing may also include a relevant discount rate and present value of flow of resource rent over all future catches.

Ultimately overfishing may lead to resource depletion in cases of subsidised fishing, low biological growth rates and critical low biomass levels (e.g. by critical depensation growth properties).

The ability for nature to restore the fisheries is also dependent on whether the ecosystems are still in a state to allow fish numbers to build again. Dramatic changes in species composition may establish other equilibrium energy flows which involve other species compositions than before (ecosystem shift). (Kill nearly all the trout, the carp will take over and make it impossible for the trout to re-establish a breeding population.)

1 Fish production and demand
2 Mitigation
- 2.1 Marine Stewardship Council
3 Instances of overfishing
4 See also
5 References
6 Further reading
7 External links

[edit] Fish production and demand

A major international scientific study released in November 2006 in the journal Science found that about one-third of all fishing stocks worldwide have collapsed (with a collapse being defined as a decline to less than 10% of their maximum observed abundance), and that if current trends continue all fish stocks worldwide will collapse within fifty years.^[1]

The FAO State of World Fisheries and Aquaculture 2004 report estimates that in 2003, of the main fish stocks or groups of resources for which assessment information is available, "approximately one-quarter were overexploited, depleted or recovering from depletion (16%, 7% and 1% respectively) and needed rebuilding."^[2]

The threat of overfishing is not limited to the target species only. As trawlers resort to deeper and deeper waters to fill their nets, they have begun to threaten delicate deep-sea ecosystems and the fish that inhabit them, such as the coelacanth.^[3] In the May 15, 2003 issue of the journal Nature, it is estimated that 10% of large predatory fish remain compared to levels before commercial fishing.^[4] Many fisheries experts, however, consider this claim to be exaggerated with respect to tuna populations ^[5].

Graph showing shark catch from 1950 to 2006

According to a brochure released by Aqua Bounty Farms, edible fish are endangered in 14 of the world's 16 major fishing areas^[6], several of which have since outlawed commercial fishing.

From 1950 (18 million tonnes) to 1969 (56 million tonnes) fishfood production grew by about 5% each year; from 1969 onward production has raised 8% annually.^[7] It is expected that this demand will continue to rise, and MariCulture Systems estimated in 2002 that, by 2010, seafood production would have to increase by over 15.5 million tonnes to meet the desire of Earth's growing population.^[8] This is likely to further aggravate the problem of overfishing, unless aquaculture technology expands to meet the needs of human population.

Overfishing has depleted fish populations to the point that large scale commercial fishing, on average around the world, is not economically viable without government assistance. By the 1980s, economists estimated that for every $1 earned fishing, $1.77 had to be spent in catching and marketing the fish.^{[citation needed]}Some species' stocks are so depleted that consumers are often unlikely to get what they think they are purchasing, due to a phenomenon called "species substitutions," where less desirable species are labeled and marketed under the names of more expensive ones. For example, genetic analysis shows that approximately 70% of fish sold as the highly-prized "red snapper" (Lutjanus campechanus) are other species.^{[citation needed]}

[edit] Mitigation

With present and forecast levels of the world population it is not possible to solve the overfishing issue; however, there are mitigation measures that can save selected fisheries and forestall the collapse of others.

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 colour 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 overfishing in articles 61, 62, and 65.^[9]

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.

Overfishing can be viewed as a case of the tragedy of the commons; in that sense, solutions would promote property rights, such as 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^[10]:

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.

On the other hand, privatisation of the highly regulated crayfish industry of Western Australia threatens its viability.^{[citation needed]}

Technology based on the splicing of certain genes in salmon and other fish, invented by Aqua Bounty Farms, a Newfoundland aquaculture company, has been shown to speed the growth rate of some fish by anywhere from 400 to 600%.^[3] They hope this will allow fish farmers using enclosed tank systems or net pens to raise their production enough to meet worldwide fish demand.

Another possible solution, at least for some areas, is fishing 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.

[edit] Marine Stewardship Council

The MSC ecolabel for sustainable seafood

The Marine Stewardship Council (MSC) is an independent, global, non-profit organization which was set up in 1997 to find a solution to the problem of overfishing. It 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 which have been independently assessed against the MSC's environmental standard and labelled to prove it. This enables consumers to play a part in reversing the decline of fish stocks. As of January 2007, 22 fisheries around the world have been independently assessed and certified as meeting the MSC standard, and there are nearly 500 seafood products sold by retailers in 25 countries around the world. Their ‘where to buy’ page lists all currently available certified seafood.

Fish & Kids is an MSC project to teach schoolchildren about marine environmental issues, including overfishing.

[edit] Instances of overfishing

Examples of the outcomes from overfishing exist in areas such as the North Sea and the Grand Banks on the east coast of North America. The result has been not only disastrous to fish stocks but also to the fishing communities relying on the harvest. Like other extractive industries such as forestry and hunting, fishery is susceptible to economic interaction between ownership or stewardship and sustainability, otherwise known as the tragedy of the commons.

The Peruvian coastal anchovy fisheries crashed in the 1970s after overfishing, following an El Niño^[11] which largely depleted anchovies from its waters.^[12]^[13] Anchovies had previously been a major natural resource in Peru; indeed, 1971 alone yielded 10.2 million metric tons of anchovies. However, in the following year, and the four after that, the Peruvian fleet's catch amounted to only about 4 million tons.^[7] This was a major loss to Peru's economy.

The collapse of the cod fishery off Newfoundland, and the 1992 decision by Canada to impose an indefinite moratorium on the Grand Banks, is a dramatic example of overfishing. ^[1]

The sole (Solea solea) 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 UK has created elements within this plan to attempt to restore this fishery; however, the expanding human population and the expanding demand for fish has reached a point where demand for food threatens the stability of these fisheries, even if not the species' survival.

[edit] See also

[edit] References

↑ "'Only 50 years left' for sea fish", BBC News. 2 November 2006.
↑ "The Status of the Fishing Fleet," The State of World Fisheries and Aquaculture: 2004.
↑ "Dinosaur fish pushed to the brink by deep-sea trawlers", The Observer Newspaper, 2006.
↑ "Rapid Worldwide Depletion of Predatory Fish Communities," Nature. 2003.
↑ "Decline of Pacific tuna populations exaggerated," Nature 434:E1-E2, 28 April 2005.
↑ ^a Aqua Bounty Farms, Update, 1(1), June 1996.
↑ "World Review of Fisheries and Aquaculture," The State of World Fisheries and Aquaculture: 2000.
↑ Text of the United Nations Convention on the Law of the Sea: Part V
↑ Aquaculture, MariCulture Systems. 2004.
↑ Benjamin, Daniel K (2001). "Fisheries are Classic Example of the Tragedy of the Commons," PERC Reports, 19(1).
↑ "Peruvian Anchovy Case: Anchovy Depletion and Trade," Trade and Environment Database, 1999.
↑ "Foreign Assistance Legislation for Fiscal Year 1982," Committee on Foreign Affairs, 1981.
↑ "Peru - Fishing," Federal Research Division of the U.S. Library of Congress.

[edit] Further reading

Clover, Charles. 2004. The End of the Line: How overfishing is changing the world and what we eat. Ebury Press, London. ISBN 0-09-189780-7
Kurlansky, Mark. (1997). Cod: A Biography of the Fish That Changed the World. New York: Walker. ISBN 0-8027-1326-2.
Loder, Natasha. 2005. Point of No Return. Conservation in Practice 6(3):28-34. On overfishing as an evolutionary force and the "Darwinian debt" for future generations.