Tuna: What’s in the Can?

The troubles with Tuna

Tuna is found in most of the world’s oceans. It ranges from small, mackerel-sized fish to the giant Atlantic bluefin tuna, which is taller than a man.

According to our collective friends at Wikipedia, there are 48 species of tuna found around the world. Of these, there are around five members of the Thunnus genus that are probably most well known to people, and that’s unfortunately through our appetite! At Seafood Watch we have researched the most commonly sought-after species.

In recent years, canned tuna has been the number two seafood item consumed in the U.S. Although consumption has fallen slightly as stories about mercury and contaminants have increased, it still remains one of the most popular seafood items consumed at home and in cafes and restaurants around the country.

Continued consumption drives demand for fishing of tuna, and for some populations this pressure is driving down stocks — some, like bluefin tuna (consumed primarily as a high-end sushi product) to the brink of commercial extinction.

Even for species such as skipjack tuna, whose numbers are not yet depleted, fishing pressure can take a heavy toll. Nets and lines set to catch tuna also indiscriminately catch high amounts of other marine wildlife. This bycatch, which even includes undersized members of the target catch, is discarded dead and dying.

Due to the high demand, falling stocks and high bycatch, the Monterey Bay Aquarium recently moved canned tuna to the “Avoid” list. With one caveat –  unless you can determine the tuna was caught in a sustainable way.

Dolphin Safe

I’m sure many of you have seen the “dolphin safe” label on the tuna cans you buy. I challenge you to find a can of tuna in the U.S. that is not so labeled! In fact, you cannot. It is not permitted in the U.S. to buy from fisheries that set nets around dolphins.

Thanks to a huge public outcry when this practice became known, U.S. consumers demanded to eat dolphin-safe tuna and it was delivered. A great accomplishment. But the little known fact is that this move away from setting nets around dolphins to catch tuna has put other ocean wildlife in danger.

As a conscious consumer, how can I know what to do?

I know that many of you reading this blog will shout “don’t eat it!” and of course that’s a very valid answer.

But what if you would like to help shift the market in favor of sustainable fishing? You can do this by voting with your dollars, and seeking out products that are not just dolphin safe, but shark safe, turtle safe and tiny tuna safe, too!

Four Tips to Tuna Sustainability

1. Look carefully at the label for how the tuna was caught. The key words to look for are “troll,” “pole,” or “pole-and-line.” This method of catching fish targets just the tuna, and results in little or no bycatch.

2. Look for the logo of the Marine Stewardship Council. This logo lets you know the fishery has been certified as sustainable to the standards of the Marine Stewardship Council.

3. Buyer beware — do not confuse “line-caught” with the more traditional pole-and-line fishing. This line is a pelagic longline. Sixty miles of line with baited hooks. These hooks snag unsuspecting seabirds like albatross seeking a meal, or catch passing sharks and sea turtles. Most of the world’s albatross species are in serious decline due to longline fishing.

4. Don’t see a fishing method? You can be a detective based on the type of tuna you’re buying — light or white. White is albacore tuna, this is usually caught by longline, as described above. So look for the pole/troll alternatives.

Light tuna can be yellowfin, skipjack, tongol, bigeye or a combination of these species. Most fishing for these tunas is by purse seine with nets set around artificial floating devices that attract marine life. Everything that seeks the shelter of the device will be netted with the tuna and later discarded.

Good luck sustainable seafood detectives! Let me know where you’re finding it.


Don’t forget to take your Seafood Watch pocket guide, or download our free iPhone app to use when ever you shop for seafood.


Monterey Bay Aquarium
Alison Barratt, Seafood Watch


W. C
W. C9 months ago


William C
William C9 months ago

Thank you.

Jim Ven
Jim Vabout a year ago

thanks for sharing.

Robert Bugtel
Robert Bugtel5 years ago

The Whole Foods store in San Antonio TX sells the "365" brand of wild Skipjack tuna that is pole & troll caught. It doesn't cost an arm and a leg, either.

Duane B.
.5 years ago

Thank you for sharing.

Faith B.
Faith Billingham6 years ago

Thanks for sharing!

Karen Simons
Karen Simons7 years ago

I printed the infornation for my area, which seems to be identical to every other area. The thought of inadvertently eating dolphin makes me sick.

Borg Drone NO MAIL
Past Member 7 years ago

Tuna is horrible, I've even stopped feeding the stuff to my cats.

Tessa D.
Tessa De Veras7 years ago

Good to know !!!!

Colin Hope
Colin Hope7 years ago