I heard that tuna is disseaparing, I "verified" on the Greenpeace link. It seems hard to believe it, is this for real? The "pig" of the oceans, one of the most common, one of the favourites? Or it's about some subspiecies? If so, what cans to avoid?
Here in The Netherlands we have the 'Viswijzer' (link is to Dutch version only). It is an index where you can lookup which types of fish you can buy just fine and which types you should not buy because they are endangered and/or not caught sustainably. I'm not sure about the exact criteria they have but according to this index:
- Albacore Tuna (white) from the Pacific with MSC-certification
- Skipjack Tuna from the Pacific with MSC-certification
- Skipjack Tuna caught by handline* in the Pacific
ORANGE (poor choice):
- White Tuna caught by handline* in the Atlantic
- Yellowfin Tuna caught by handline* in the Pacific, Indian and Atlantic Ocean
- Skipjack Tuna caught by handline* in the Pacific and Indian Ocean and Indonesia
RED (don't buy)
- White Tuna caught (other methods) in the Atlantic, Pacific or Mediterranean
- Yellowfin Tuna caught (other methods) in the Atlantic, Pacific or Indian Ocean.
- Skipjack Tuna caught (other methods) in the Indian and Eastern Atlantic Ocean.
UPDATE: An alternative to MSC-certified tuna is 'fishless tuna'. In The Netherlands it is made by a company called 'Vegetarian Butcher'. I just tried it this week. It's soy-based, tastes suprisingly good, very much like tuna. A quick google search showed that there are also other companies who sell something similar.
Please eat tuna only from the cans with MSC (Marine Stewardship Council) label, avoid pizzas or sandwiches that cannot provide such certification. (See the approved answer of @THelper (and the comments) for more details, this is the short answer!)
In north america we have Seachoice.org. They make a handy pocket guide. Yellowfin tuna is on the red (bad) list. But they say canned Albacore is ok.