A research done at the University of California Los Angeles (UCLA) and Loyola Marymount University (LMU) recently revealed that an estimated amount of 47 percent of fish served in Sushi restaurants in the Los Angeles area are found to be mislabeled. With halibut and red snapper as the biggest offenders, the study's results lead to the question if the issue of mislabeling is out of mistranslation, or a deliberate fraud.

The study, which was conducted from 2012 to 2015 by Biology students as part of their graduate studies, had the researchers order from 26 sushi restaurants in LA, which were determined by their reviews. Targeting some of the most popular fishes used for sushi like red snapper, halibut, mackerel and several types of tuna, they order from the restaurants every year and analyze the DNA of the fish meat to determine its category.

According to the Huffington Post, 47% of the 323 samples they obtained over the course of the study were mislabeled. Flounder was always used as a replacement for halibut, while red snapper was replaced with one of eight different types of fish, with red sea bream being the most common.  Conversely, salmon was mislabeled around 13 percent, while mackerel for eight. Bluefin tuna, out of all the tuna tested, came out as correct all the time.

The study also included three high-end grocery stores. According to Mail Online, 42 percent of fish sold at those stores are also mislabeled.  Samantha Cheng, who is part of the research group, has stated that more commonly known or popular types of fish are found time and time again to be replaced by a variety or a different species of fish. This could point out the bait and switch could be happening somewhere else in the supply chain, as both retailers and consumers fall victim into the swap.

Paul Barber, a professor at UCLA, has pointed out that for some types of fish, the mislabeling may come out of "regulatory semantics" or mistranslation, as "madai" in Japan usually is served with red sea bream snapper, its translation in the US would be red snapper. The FDA, though, has made it clear in its regulations that only northern red snapper can be sold as red snapper in the US.

Aside from possible fraud and misleading customers, this issue also raises some health concerns. Olive flounder, used to replace halibut, has caused a rampant food poisoning in Japan sometime back. 

Fans of this Japanese dish are advised to ask, if possible, the specific species of the fish used and its source.