tuna

Personally, years ago so far, i took the decision to eliminate tuna fish from my diet. I used to eat it, to like it. Then thanks to my work, i got knowledge and consciousness about the several different issues surrounding tuna fishing activity, and market. One can choose among several reasons to stop eating tuna, and all of them remain a good valid reason just by itself. Just to name some of them: Overfishing, ocean conservation, high toxic contaminant load in tuna meat, high concentration of mercury, species conservation and the interactions of tuna fishing activity with whales and dolphins. The list is quite long and the above mentioned reasons are just a little part of the whole problem. But regarding the last reason, the negative interactions of tuna fishing with the conservation and protection of whales and dolphins, the issue is quite big and for some aspect controversial.

Just to give you a slight idea of it, in the tropical waters of the Pacific Ocean west of Mexico and Central America, large yellowfin tuna (Thunnus albacares) swim together with several species of dolphins: pantropical spotted, Stenella attenuata, spinner, S. longirostris, and common, Delphinus delphis, dolphins. This ecological association of tuna and dolphins is not clearly understood, but it has had two important practical consequences: it has formed the basis of a successful tuna fishery, and it has resulted in the deaths of a large number of dolphins. This is the heart of the tuna-dolphin issue.

The number of dolphins killed since the fishery began in the late 1950s is estimated to be over 6 million animals, the highest known for any fishery. For comparison, the total number of whales of all species killed during commercial whaling in the 20th century was about 2 million. The bycatch of dolphins in the ETP tuna fishery has now been successfully reduced by more than 99%, but even at the present level of about 1,000 dolphins/year, it remains among the largest documented cetacean bycatch in the world.

From the late 1980s, cans of “dolphin safe tuna” started to appear in U.S. grocery stores. Brands carrying these labels were preferentially purchased by consumers who understood the importance of reducing the massacre of dolphins. But you know what? Not all the “dolphin safe tuna” are actually reliable! The problem was highlighted years ago (example here: “Dolphin-friendly tuna? Don’t believe it“) and now has been proposed again in the report “25 Amazing (and Weird) Facts about How Food is Made and Where it Comes From.

Enjoy your reading and make the right choices (about making the right choices, this might be of help in deciding what to buy and eat – related post fancy mobiles & responsible consumption of natural resources)!

Further reading:

Bearzi G. 2009. When swordfish conservation biologists eat swordfish. Conservation Biology 23(1):1-2.

Gerrodette, T., G. Watters, W. Perryman, and L. Ballance. 2008. Estimates of 2006 Dolphin Abundance in the Eastern Tropical Pacific, with Revised Estimates from 1986-2003. NOAA Tech. Memo. NMFS-SWFSC-422.

Gerrodette, T., G. M. Watters, and J. Forcada. 2005. Preliminary estimates of 2003 dolphin abundance in the eastern tropical Pacific. Southwest Fisheries Science Center, Administrative Report LJ-05-05, 26 p.

Gosliner, Michael L., 1999. The Tuna-Dolphin Controversy. Pages 120-155 in Conservation and Management of Marine Mammals, John R. Twiss, Jr. and Randall R. Reeves (eds.), Smithsonian Institution Press, Washington, D.C.

Joseph, James. 1994. The tuna-dolphin controversy in the eastern Pacific Ocean: biological, economic, and political impacts. Ocean Development and International Law 25, 1-30.

National Research Council, 1992. Dolphins and the Tuna Industry. National Academy Press, Washington, D.C.

Perrin, William F. 1969. Using porpoise to catch tuna. World Fishing 18: 42-45.

Perrin, William F. 2004. Chronological bibliography of the tuna-dolphin problem, 1941-2001. NOAA Tech. Memo. NMFS-SWFSC-356.

Wade, P. R., Watters, G. M., Gerrodette, T., and Reilly, S. B. (2007). Depletion of spotted and spinner dolphins in the eastern tropical Pacific: modeling hypotheses for their lack of recovery. Marine Ecology Progress Series 343, 1-14.

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