Kate Stoeckle and Louisa Strauss, who graduated from high school this year, have discovered that not all sushi fish is labeled properly. It started over dinner: Katie's dad, Dr. Stoeckle, works with DNA bar coding. "Could you bar code sushi?" Katie asked. He replied, "Yeah, I think you could - and if you did that, I think you'd be the first ones." Katie asked Louisa to help collect her samples. As Dr. Stoeckle put it, "It involved shopping and eating, in which they were already fluent." They went to 4 restaurants and 10 grocery stores in Manhattan, then sent tiny pieces of fish off to a lab in Ontario. Two of the 4 restaurants and 6 of the 10 grocery stores had sold mislabeled fish. White tuna turned out to be Mozambique tilapia. Roe supposedly from flying fish was actually from smelt. (And so on.) Know what you're getting, don't let your sushi chef off the hook! [NY Times, Reuters]
I think, also, that Grouper and Red Snapper being sold in supermarkets (especially not-whole) are not actually Grouper and Snapper. Chilean Sea Bass, as well. The fact is, most fish is mild, and most mild foods taste very similar, and most average people do not have the kind of palates to be able to tell which fish is which, especially when one may have only a minute flavor difference from another.
So for the most part this kind of thing shouldn't bother us — especially not in supermarket sushi, which is, well, supermarket sushi — but if you notice a large price difference in a restaurant and don't feel like what you're eating is really what you thought you were getting, you should raise some hell.
Also: ALWAYS ask the sushi chef what is good that particular day. You will never, EVER regret it.