As NBC 5 Responds continues to dive into seafood fraud, testing from various markets and restaurants around the Chicago area have revealed frequent instances of mislabeled fish being sold.
This fall, NBC 5 Responds investigative reporter PJ Randhawa worked with Dominican University as they tested various fish samples from eateries and markets across the region.
"I was really shocked at how much fish is mislabeled," Dominican student Ryan Barnett said.
A 2019 study from Oceana, an ocean conservation group, found that approximately 20% of fish samples across the U.S. were mislabeled.
“I thought, oh, I can do this [testing]. I'd love to try this with my students,” Dr. Irina Calin-Jagman, a Biology Professor at Dominican University, said. Dr. Calin-Jagman said she’s been doing fish sample testing with her students for the past six years.
Dr. Calin-Jagman invited NBC 5 Responds to join her biology class, as the students fact-checked the labels on their seafood through DNA sequencing.
Each student brought in two fish samples – most from a local grocery store or their favorite sushi restaurants around the Chicago area.
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"One of the things with our study is that it has to be raw fish, so we can't use cooked fish," Calin-Jagman said.
The class brought in a variety of samples, such as red snapper, catfish, swordfish, cod and sea bass.
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Students begin by working to isolate DNA from their fish samples, looking to find what's known as the "barcoding gene," which Calin-Jagman said is the standard used to identify different species.
From there, the samples are sent off to a DNA sequencing lab.
“We can then put it in these nationally available, internationally available databases and we can say, ‘what does it match,'” Calin-Jagman said.
Calin-Jagman was able to evaluate 84 samples, with the results bearing some bad news for fish with white flesh, such as Red Snapper.
“So what we found is not surprising. It’s what I have found for the last several years that I've been doing this, which is red snapper is always is something else other than red snapper, especially when you get it from a restaurant,” Calin-Jagman said.
“I bought a Sea Bass and I bought a Red Snapper sample, and I thought they looked completely different. And it turns out they were the exact same fish,” Barnett said.
Samples of "white tuna" and "super white tuna" turned out to be escolar.
“Escolar is not tuna. It's a completely different species of fish. And it actually has really, really high mercury levels. It can be dangerous for pregnant women, and it's banned from selling in a lot of Europe and in Japan,” Barnett said.
For salmon and other tuna, the testing showed that the fish almost always matched the labeling.
“Salmon is almost always salmon, tuna is very often tuna,” Barnett said.
Although this testing was done on a much smaller scale than Oceana’s study, the results showed Chicago-area fish samples are mislabeled up to 30% of the time.
“I would personally stick to tuna and salmon myself. If you're adventurous, obviously there are lots of other fish you can try at sushi restaurants, but it's both good news and bad news, right?” Calin-Jagman said.
Here are some key takeaways from the Dominican University testing:
- If you're shopping for an expensive fish, such as red snapper, your chances of getting the real deal are much better if purchased at a grocery store.
- When in doubt, buy the full fish.
- Be thoughtful on where you purchase your seafood. Several grocery stores advertise seafood sourcing programs, which allow you to track fish from the sea to the store.
