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   home/sustainability on coral reefs/how much reef do you need

Healthy coral reefs supply plenty of fish; damaged reefs don't.

How Much Reef Do You Need?

Ecosystems can supply a certain amount of food sustainably. Take food faster than it regenerates and the ecosystem becomes unsustainable and productivity drops. Coral reefs are no exception despite being one of the world’s most productive ecosystems. Overfishing strips fish from the reef and erodes ecosystem health. We need to use coral reefs sustainably for a constant supply of food because unhealthy reefs are unproductive.

 How much fish do coral reefs produce?

Studies estimate that 1 km2 (about 250 acres) of high quality reef can sustainably produce between 15 and 20 tonnes (1 tonnes = 2205lb) of fish each year. Poor quality reefs produce less than 5 tons.

 So what does that mean to the people of Pohnpei?

30 000 people live on Pohnpei Island in the Federated States of Micronesia. About 60 miles of reef surround this island giving each person about 10 feet of reef front and an acre of lagoon to gather food in.

This amounts to about 130-200 lbs (60-90 kg) of fish per person that can be sustainably caught from a healthy reef each year. This is enough fish for everyone on the island. In contrast, an unhealthy reef would provide less that 27lb (12kg) of fish per person per year. An unhealthy reef can’t support the people of Pohnpei.

Commercial fishing can catch any excess fish production to gain foreign earnings. But commercial fishing comes with a risk.

 Local vs. commercial fishing

Commercial fishing is necessary to feed the world’s population but fishing unsustainably erodes the health of marine ecosystems making them less productive. This reduces the amount of fish we can take in the long run. Sustainable, local fishing is a key goal for coral reef ecosystems

We are almost too good at fishing. We have been overfishing marine ecosystems for at least 2500 years, and have depleted more than 90% of formerly important fish stocks. The rate that we are depleting marine resources has been accelerating over the last 150-300 years as our numbers boom and fishing equipment becomes more sophisticated. There is even the chance that all present commercial fish stocks will be depleted by 2050.  Modern fishing methods are efficient, but tend to be destructive and can easily strip a reef of fish.

Commercial fishing can be done sustainably if we know how much an ecosystem can produce and we resist the temptation to take too much.

 Reef fish and sustainability

Overfishing lowers a reef's diversity and productivity. This also lowers resilience and makes the reef vulnerable to other types of disturbance. Fishing sustainably preserves productivity and diversity over the long term.

 References

FAO Fisheries and Aquaculture Department. (2007). State of the world fisheries and Aquaculture 2006. The Food and Agriculture Organization of the United Nations. PDF retrieved 5 August 2008 from ftp://ftp.fao.org/docrep/fao/009/a0699e/a0699e.pdf.

Halpern, b. et al. (2008, February 15). A global map of human impact on marine ecosystems. Science 319: 948-952.

Hawkins, M. & Roberts, C. (2004, February). The effects of artisanal fishing on Caribbean coral reefs. Conservation Biology 18(1): 215-226. PDF retrieved 25 August 2008 from http://www.sefsc.noaa.gov/sedar/download/S8DW_18.pdf?id=DOCUMENT.

Henderson, M. Fishing subsidies ‘destroy oceans’ say scientists. Times Online. Retrieved 5 August 2008 from http://www.timesonline.co.uk/tol/news/world/us_and_americas/article1409219.ece.

Jackson, J. et al. (2001, July 27). Historical overfishing and the recent collapse of coastal ecosystems. Science 293: 629-638.

Lotze, H. et al. (2006). Depletion, degradation, and recovery potential of estuaries and coastal seas.  Science 312, 1806-1809. Retrieved 25 August 2008 from http://www.sciencemag.org/cgi/reprint/312/5781/1806.pdf?ijkey=7uCXREKwGAyPw&keytype=ref&siteid=sci.

MSC. MSC environmental standard for sustainable fishing. Marine Stewardship Council.  Retrieved 25 August 2008 from http://www.msc.org/about-us/standards/msc-environmental-standard.

National Academy of Sciences. (2002). Dietary Reference Intakes (DRIs): Recommended Intakes for Individuals. National Academy of Sciences. PDF retrieved 11 August 2008 from http://www.iom.edu/Object.File/Master/21/372/0.pdf.

Parsell, D. (2002, February 26). High-Tech Fishing Is Emptying Deep Seas, Scientists Warn.  National Geographic. Retrieved 11 August 2008 from http://news.nationalgeographic.com/news/2002/02/0225_0226_fishcrisis.html.

Roberts, C. (2007). The unnatural history of the sea. Island Press: Washington.

UN Atlas of the Oceans. (2007, July 17). The value of coral reefs. UN Atlas of the Oceans. Retrieved 28 August 2008 from http://www.oceansatlas.org/servlet/CDSServlet?status=ND0zMTgxOCZjdG5faW5mb192aWV3X3NpemU9Y3RuX2luZm9fdmlld19mdWxsJjY9ZW4mMzM9KiYzNz1rb3M~

White, A. & Savina, G. (1987). Reef fish yield and nonreef catch of Apo Island, Negros, Philippines. Asian marine biology 4: 67-76.

Worm, B. et al (2006, November 3). Impacts of Biodiversity Loss on Ocean Ecosystem Services. Science 314: 787-790. Retrieved 28 August 2008 from http://www.sciencemag.org/cgi/content/full/314/5800/787.

WWF. (2008, February 29). Problem: Poorly managed fisheries. World Wildlife Fund. http://www.panda.org/about_wwf/what_we_do/marine/problems/problems_fishing/index.cfm.

Zabel, R. et al. (2003). Ecologically sustainable yield. American Scientist 91: 150-157. PDF retrieved 25 August 2008 from http://marine.rutgers.edu/courses/expl_oceans/Zabel1.pdf.

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