|There are several types of tuna – Albacore, Bigeye, Bluefin, Skipjack, and Yellowfin. Bluefin tuna is in severe decline worldwide thus, is never considered sustainable. The sustainability rating of the other species depends on how they are caught. Fresh tuna (ahi, loins, steaks, tombo and sashimi) is usually caught by long-line which has high environmental impact and is discouraged by our program; however we can help you find trolled or handline caught tuna.
Long lines are made up of thousands of baited hooks strung on a line 20-50 miles long and left at sea for days. Not surprisingly, sharks, sea turtles, sea birds, and marine mammals are caught and killed as unwanted “bycatch.” Over 100,000 sea turtles are killed yearly in the global long-line industry, increasing their already high risk of extinction. Juvenile tuna are also indiscriminately caught by long-lines. In some situations over 75% of the tuna caught are juveniles and must be discarded by law. Generally less than half of what is caught is taken to port. This wastefulness is what puts long-lined tuna on the avoid list.
The exception is U.S. caught long-lined tuna, because strict long-lining regulations about how hooks are set and how frequently lines are pulled have reduced the amount of bycatch. Observers on U.S. tuna boats record turtle deaths and the entire fishery is closed for the season when the maximum allowable number are taken (just 17 leatherback turtles total).
Troll/pole or hand-line caught tuna is most common from Hawaii and the western U.S. including the Santa Barbara Channel and Central Coast. It is the best choice for tuna because it targets the tuna specifically to avoid incidental catch of sharks, sea turtles and other unwanted fish. Wild Planet (www.safetuna.com) sells a canned U.S.-caught trolled tuna that is also very low in mercury content and can be ordered in bulk online or through a distributor.
Canned tuna is tricky. “White” canned tuna is usually albacore. About 60% of white tuna sold in the US is internationally caught using longlines and so is on the Avoid list. The other 40% is from US or international troll fisheries, and is considered good. Southern and Central California canned tuna (e.g., American Tuna, Rincon Gold or Wild Planet) is primarily troll/pole caught and is the best choice for canned tuna. These local products also tend to be very low in mercury. “Light” tuna is mostly skipjack but sometimes bigeye. A small amount of light tuna sold in the U.S. is troll/pole caught, and is a recommended choice.
The majority, about 80%, is purse-seine caught, where a large net encircles an entire school of tuna. Schools are targeted by finding pods of dolphin, which travel with tuna because they share their prey. The majority of purse-seine tuna is labeled dolphin safe because efforts are made to minimize dolphin mortality. A fraction of purse-seine tuna, even dolphin safe tuna, is caught using a “fish aggregating device” or FAD that attracts tuna. FAD fishing is associated with high bycatch, and so FAD purse-seined tuna is on the Avoid list. In most cases, you cannot tell from the label whether FADs were used, so all purse-seine tuna should be avoided.
In summary, for canned tuna, your best choice is local troll/pole caught, and second would be international troll/pole caught.