Tuna, Atlantic bluefin (Farmed)

Thunnus thynnus

Method of production — Farmed
Production country — Mediterranean
Production method — Marine net pen, capture based aquaculture
Picture of Tuna, Atlantic bluefin (Farmed)

Sustainability rating five info

Sustainability overview

Farming or ranching of Bluefin tuna relies on capture of juvenile wild tunas for on-growing and fattening in open net cages until harvest. Therefore this process is completely reliant on overexploited wild fish stocks, and farming in this way will not lessen the pressure on the species. In the case of Mediterranean sea ranching operations, the capture of tuna for ongrowing is an increasing part of the catch. The ranching of tuna requires large amounts of fresh fish for feeding, with up to 20 kg of wild fish required to produce 1 kg of Bluefin Tuna resulting in a significant net loss of fish protein.

Feed Resources

Criterion Score: -4

Bluefin tuna are fed whole fish the sourcing and sustainability of these is unknown. Tuna grown in fattening pens (as opposed to true fish farming) have a high demand for fish requiring much more that any other farmed finfish species.

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Environmental Impacts

Criterion Score: FAIL

As Bluefin tuna are not truly farmed, they are caught as juveniles and transported to areas for on-growing in fattening cages until they reach harvest size. As this process relies on the capture of juvenile endangered, depleted stocks the assessed for tuna is an automatic red rating - fish to avoid.

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Fish Health and Welfare

Criterion Score: -1

There are no known welfare or humane slaughter standards for Bluefin tuna.

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Management

Criterion Score: -4

With the exception of some countries Aquaculture Zoning and Environmental Impact Assessments there is little transparency in relation to regulations applying opt Bluefin tuna ranching. No independent certification currently applied to this species.

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Production method

Marine net pen, capture based aquaculture

Bluefin tuna can be ‘farmed’, although the farming is unlike other aquaculture. The tuna are captured by purse-seine nets and transferred to a towing sea-cage. These cages are towed out to sea where the tuna are then transferred to grow out sites, where they are fattened on a combination of fresh and pellet feed. This is more accurately termed as ranching.

Alternatives

Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below. Click on a name to show the sustainable options available.

Anchovy, anchovies
Arctic char
Herring or sild
Salmon, Atlantic (Farmed)
Salmon, Chinook, King Salmon
Salmon, Chum, Keta, Calico or Dog salmon
Salmon, Coho , Silver, White
Salmon, Pink, Spring , humpback
Salmon, Sockeye , Red Salmon, Bluebacks, Redfish
Sprat, whitebait
Swordfish
Trout, Rainbow
Tuna, albacore
Tuna, bigeye
Tuna, skipjack
Tuna, yellowfin

Biology

Tuna belong to the family Scombridae. They are large, oceanic fish and are seasonally migratory, some making trans-oceanic journeys. Northern bluefin can grow to over 300 cm and reach more than 650 kg. They can achieve ages of 20 years or more. Maturity is reached at around 4-5 years. They are generally found in schools. Spawning occurs in two areas in the Atlantic: the Gulf of Mexico from April to June and in the Mediterranean from June to August.

References

Ottolenghi, F. 2008. Capture-based aquaculture of bluefin tuna. In A. Lovatelli and P.F. Holthus (eds)

Capture-based aquaculture. Global overview. FAO Fisheries Technical Paper. No. 508. Rome, FAO. pp. 169-182.