Factsheet 1: Tuna
PartIII:TRAFFICRecommends
By-catch of non-target species: There are three main fishing methods for catching tuna: purse seine, pole and line, and long-line. Other methods include troll lines, hand lines and driftnets. In a few high-value fisheries, traditional methods are still used, for example Atlantic blue-fin tunas are taken in traps in the Mediterranean and east Atlantic, and by harpoons off the coast of North America. The level of by-catch varies according to the gear type:
• Long-line fishing, which is the most common method for catching albacore, big-eye and blue-fin, results in the by-catch of sharks, sea turtles, billfish and seabirds.
International long-line fleets are contributing heavily to the long-term decline of some of these threatened or endangered species. The U.S. Atlantic and Hawaiian long-liner fleets are subject to strict by-catch regulations.
• Purse-seining, which is used for several species, is particularly damaging if tuna schools are targeted by encircling dolphins on the surface in order to net tuna
(particularly large yellow-fin) that tend to school beneath them. Both dolphins and tuna are caught in the nets, which in the past has killed millions of dolphins. This practice has been much reduced (see ‘dolphin-safe tuna’
below), but purse seine nets may still catch large amounts of by-catch, although the technique of
slackening nets to allow dolphins to escape reduces the problem. If they are set on floating objects or ‘fish aggregating devices’ (FADs), the by-catch can include young big-eye and yellow-fin tuna, and other pelagic fish and sharks.
• Hook and line, pole and line, harpoon, and trap fishing have very little by-catch. For example, albacore is fished either by trolling with artificial lures on or near the surface and with pole and line, or by using bait to attract the fish, which are then hooked with a jigging pole off the stern and landed individually. Barbless hooks are used, and the lack of nets ensures the fishery is ‘dolphin free’.
©JorgeBARTOLOME/WWF-Canon
Management problems: Although individual countries are responsible for managing tuna stocks that occur and are fished within their own waters, much tuna fishing takes place on the high seas, where it is managed by regional fisheries management organisations (RFMOs). In practice, however, the advice of these RFMOs is sometimes disregarded. Japan, for example, has caught double its quota of Southern blue-fin tunas for the last 20 years and some Mediterranean countries appear to have disregarded quotas, too.
Sea-ranching: The migratory, fast swimming life-style of tuna means that they are not suitable for farming. However, sea ranching is carried out for blue-fin tuna in the
Mediterranean, Mexico and Australia. This involves fattening wild caught fish in floating cages for a few months to two years. The technique has had significant management issues, with environmental problems and an increase in fishing effort, leading to calls for a moratorium on the practice and better enforcement of minimum size for catches of juvenile tuna.
Species to choose
Albacore:
• American Albacore Fishing Association (AAFA) pole and line and troll fisheries in the North and South Pacific.
Marine Stewardship Council (MSC) certified in 2007.
• British Columbia (troll/pole) and Hawaii (troll/pole/hand-line/long-line).MBA ranking: Best choice.
Big-eye:
• Hawaii (troll/pole and hand-line) and worldwide (troll/pole).MBA ranking: Good alternative.
Skipjack:
• Pole and line, and troll fisheries worldwide.MBA ranking:
Best choice – although the Marine Conservation Society (MCS) rates this fishery 3, or cause for concern.
• Hawaii, hand-line.MBA ranking: Best choice.
• Hawaii, long-line.MBA ranking: Good alternative (due to strict by-catch regulations).
Yellow-fin:
• U.S. Atlantic Ocean, pole and troll.MBA ranking:
Best choice.
• U.S. Atlantic Ocean, long-line.MBA ranking: Good alternative.
• Pole and troll worldwide.MBA ranking: Good alternative – although MCS rates this fishery 3, or cause for concern.
• Hawaii, hand-line.MBA ranking: Good alternative.
‘Dolphin-safe or –friendly’ canned skipjack, albacore and yellow-fin:
This is tuna caught using methods that do not involve the deliberate hunting, capture and death of dolphins, e.g.
trolling, pole or hand-line, or with purse seine nets, according to a strict set of standards including:
• No intentional chasing, netting or encirclement of dolphins;
• No use of drift gill nets to catch tuna;
• No accidental killing or serious injury to any dolphins during net sets;
Factsheet 1 continued
©MichelGUNTHER/WWF-Canon
PartIII:TRAFFICRecommends
• No mixing of dolphin-safe with other tuna in individual boat wells, or in processing or storage facilities; and
• Fishing trips in the eastern tropical Pacific Ocean by vessels of a certain size to have an independent observer on board.
Purse seine fisheries for skipjack and yellow-fin tuna in the Atlantic:
Low levels of by-catch and low interaction with marine turtles and marine mammals.
Species of particular concern
• Northern or Atlantic Blue-fin: Whilst individuals caught legally and over 30 kg in size may be sustainable, it is virtually impossible for consumers to know if that was the case prior to filleting and processing.MCS rating: 5 (avoid); MBA ranking: Avoid.
• Southern Blue-fin:MCS rating: 5 (avoid).
• Pacific Northern Blue-fin:MCS rating: 5 (avoid).
• Farmed or ranched blue-fin tunas: Farming of these species relies on capture of juveniles from the wild.
• Long-line caught Big-eye:MCS rating: 5 (avoid); MBA ranking: Avoid.
• Long-line caught albacore in the South Pacific:
MBA ranking: Avoid. This fish is usually larger than other albacore and its meat is pinkish red instead of light brown. It is often marketed under its Hawai’ian name, tombo or tombo ahi.MCS rates albacore from the south Atlantic and Pacific (including Hawaii) as 4 (cause for concern).
• Long-line caught skipjack (except Hawaii) and yellow-fin (except U.S. Atlantic):MBA ranking: Avoid.
Environmental Defense, a U.S. non-governmental
organisation, has issued a health advisory for all long-line-caught tuna, and for all canned tuna, due to elevated levels of mercury. There is no health advisory for troll/pole-caught fish as these involve younger tuna with lower mercury levels.
For more information, see www.oceansalive.org or www.edf.org
Sources of further information
Australia’s Sustainable Seafood Guide – available from the Australian Marine Conservation Society:
http://www.amcs.org.au/default2.asp?active_page_id=137 Blue Ocean Institute Guide to Ocean Friendly Seafood:
www.blueocean.org/seafood
Commission for the Conservation of Southern Blue-fin Tuna:
www.ccsbt.org
Earth Island Institute’s information on certified “dolphin-friendly or -safe” tuna:
www.earthisland.org/dolphinSafeTuna/consumer/
Lack, M. (2007). With an eye to the future: addressing failures in the global management of big-eye tuna. TRAFFIC International and WWF Australia.
Marine Conservation Society’s Sustainable Seafood Guide:
www.fishonline.org
Marine Stewardship Council: http://eng.msc.org/
Monterrey Bay Aquarium Seafood Watch:
www.mbayaq.org/cr/seafoodwatch.asp
Seafood Choices Alliance: www.seafoodchoices.com WWF Seafood Guides – available for Belgium, Denmark, Finland, France, Germany, Hong Kong, Indonesia,
Netherlands, Norway, Poland, South Africa, Spain, Sweden, Switzerland:
http://www.panda.org/about_wwf/what_we_do/marine/our_
solutions/sustainable_fishing/sustainable_seafood/seafood_
guides/index.cfm