No one wanted to eat a toothfish. It sounded gross. So in the 1970s, fishmongers marketed Patagonia toothfish (Dissostichus eleginoides) from the southern reaches of our globe as ‘Chilean sea bass’. The long-lived fish was promptly overfished (overfishing is widespread; it’s difficult to feed our growing demand for seafood).

The overfishing of Chilean sea bass got a bunch of attention: Al Gore got in trouble for eating it at his daughter's wedding, the fish was de-shelved at Whole Foods and Wal-Mart and was boycotted by chefs. Then in stepped the Marine Stewardship Council (MSC), which certified a small, distinct population of Chilean sea bass in UK territorial waters, in the midst of heavy overfishing of the Antarctic populations (read more on the back story here). This led to contention during certification, with particular emphasis on the likelihood that the two populations would be mixed in the marketplace. Don’t worry, the MSC said. We have an excellent traceability scheme, even in a seafood market where mislabeling is pervasive. We’ll be able to easily trace and separate the good, abundant fish from the bad, endangered fish.

The worry was justified. Consumers are being duped.

In a study published in Current Biology this week, authors used mtDNA to genetically analyzed 36 samples of MSC-certified Chilean sea bass. Not all the samples were from the certified stock in UK waters. In fact, not all the samples were D. eleginoides – 3 were another species altogether. Out of the remaining 33, 5 were not from the certified area. At least 15% mislabeled. Also looked at 19 not-certified Chilean sea bass samples, 13 of which were labeled as having originated from Chile, 46% (6 of 13) were not from Chile. Read more about the study at Science.

The difficulty with MSC-certified seafood, unlike organic food, for instance, is that the product is similar but the means of production is different. This makes it very difficult to detect fraud, especially in a simple way. These scientists used genetic sequencing to determine if the MSC's claims of traceability were correct. The fact that uncertified fish are masquerading as MSC is more evidence that the MSC makes false promises to consumers who genuinely want to do the right thing. Not only do we need to question whether the certification has meaning, but now we must ask whether eco-labeled fish are actually certified.