Post by Eliza Barclay, The Salt at NPR Food

There are so many fish in the sea. But from a diner's viewpoint, peering down at a sliver of white fish atop a bed of sushi rice, a lot of them look the same.
Now a report from the ocean conservation group Oceana confirms that there's a pretty decent chance that fish on the plate or on ice in the seafood case is not what it's labeled to be. That means that seafood wallet cards designed by conservation groups to help steer consumers towards sustainable choices may not be doing much good.
Between 2010 and 2012, Oceana took 1,215 seafood samples from 674 retail outlets in 21 states. When they tested the DNA, they found that 33 percent were mislabeled. Sushi vendors and grocery stores were the most likely outlets to sell mislabeled food, though Oceana says the fraud can happen before it reaches them.
Earlier investigations by Oceana and the Boston Globe revealed that seafood mislabeling is common in cities like New York and Boston, where people eat a lot of fish. But the report out Thursday shows it's happening across the country, and is as bad or worse in places like Texas and Colorado. Some 49 percent of the retail outlets sampled in Austin and Houston sold mislabeled seafood, while 36 percent in Colorado did so.