Two resourceful high school students have done a rather clever investigation of some sushi in New York city. Apparently many of the stores and restaurants have been caught selling product that was not what it claimed to be.
The article does point out that the sample size of the girls' experiment is a little small to draw dramatic conclusions from, but it IS larger enough for one to be "concerned." Clearly more investigation needs to be done.
As someone who has worked in restaurants and grocery stores, I'm going to wager a guess - total guess - that the fault lies not with the stores and restaurants, but with the suppliers. Somebody far up the supply chain is pulling a fast one, but nobody has noticed all the way down.
I know from experience that certain kinds of fish can be very difficult to distinguish from others once they are cut. That is, fillets from two different fish can be almost next to impossible to tell apart, depending on the fish.
If an switch is made far enough up the line, and a fish gets mislabeled, the nobody would notice it ... ever.
I read this a couple days ago in the NY Times. Unfortunately, the only things I thought of were "Wow, these girls will have something really good to write about for their college applications," and "Damn it, I better be paying for white tuna when they say I'm eating white tuna!"