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Overfishing is a situation where one or more fish stocks are reduced below predefined levels of acceptance by fishing activities. More precise definitions are provided in biology and bioeconomics. 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. Economic or bioeconomic overfishing in addition to the biological dynamics takes into consideration the cost of fishing and defines overfishing as a situation of negative marginal growth of resource rent. A more dynamic definition may also include a relevant discount rate and present value of flow of resource rent over all future catches.

Ultimately overfishing may lead to 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).

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."

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. 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. Many fisheries experts, however, consider this claim to be exagerated with respect to tuna populations .

Fish production and demand

According to a brochure released by Aqua Bounty Farms, edible fish are endangered in 14 of the world's 16 major fishing areas, 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. 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. 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 economially 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. Some species' stocks are so depleted that consumers are often unlikely to get the particular species 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.

Solutions

In order to meet the problems of overfishing principles of 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.

  • 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.

Free market environmentalists propose privatization as a solution to overfishing. 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:

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 otherhand, privatisation of the highly regulated crayfish industry of Western Australia threatens its viability.

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%. They hope this will allow fish farmers using enclosed tank systems or net pens to raise their production enough to meet worldwide fish demand.

Instances of overfishing

Examples of the outcomes from overfishing exist in areas like 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 forestry and hunting, fishery crisis is susceptible to economic interaction between ownership or stewardship and sustainability, or the tragedy of the commons.

The economic system of Peruvian coastal anchovy fisheries crashed in the 1970s after overfishing, and reportedly an El Niño largely depleted anchovies from its waters. 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. This was a major loss to Peru's economy.

See also

References

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

External links

Ecology | Fishing industry Fisheries science Überfischung Overbevissing Sobrepesca

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Overfishing".

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