To all seafood and especially sushi lovers take care of what you’re eating. Oceana Study Reveals Seafood Fraud Nationwide and here’s a selection from their report on white tuna.
The majority of the tuna samples in this study were label[l]ed as “white tuna.” Of the 66 white tuna samples, 62 were mislabel[l]ed (94 percent). Eighty*four percent of the white tuna samples were actually escolar ( 52 of the 62) (Figure 10). The remaining white tuna mislabel[l]ing (16 percent) came from the substitution of one type of tuna for another or the use of a non-acceptable market name. A fish product referred to as “white tuna” is only acceptable as a market name when sold in a can. 30 Otherwise, “albacore tuna” or “tuna” is the acceptable market name for that same fish, Thunnus alalunga, when sold outside the can, fresh or frozen.
Swapping escolar for white tuna is not only illegal , but it can also cause serious health problems. Escolar, or oilfish (Lepidocybium flavobrunneum), is not actually a tuna species at all, but is instead a snake mackerel that contains a naturally occurring toxin, gempylotoxin. This toxin can cause mild to severe gastrointestinal problems even for some who eat only a few ounces of the fish. Because of the health problems associated with escolar, Italy and Japan have banned it, several other countries have issued health advisories for it 31 and the FDA advises against the sale of it in the U.S.
59% of the ‘Tuna’ Americans Eat Is Not Tuna, The Atlantic (original page)
Oceana Study Reveals Seafood Fraud Nationwide (PDF)