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As of right now there are several groups that "certify" and put a label on sustainable fish, the most prominent of which is the Marine Stewardship Council, an independent, non-profit organization based in the UK. Established in 1999 as a joint effort between industry (Unilever) and conservation (WWF), the MSC has certified 857 products as of September 2007 (MSC 2007). Before
Also, if producers want to have their fish evaluated and certified, there is a cost barrier that bars out small fishing companies who cannot afford to apply for certification. Since a substantial portion of the fish sold in the U.S. canned tuna, perhaps focusing on labeling tuna that is caught in sustainable fisheries is the first step.
-- (2007). "About MSC." Retrieved on November 18, 2007, from http://www.msc.org/html/content_462.htm
Someone needs to go through this information:
http://oregonstate.edu/dept/IIFET/2000/papers/donath.pdf
http://www.uri.edu/cels/enre/docs_CRoheim/ecolabel.pdf
http://www.msc.org/assets/docs/fishery_certification/InfoSheet4_Costs.pdf