Bluefin, yellowtail, yellowfin — can most people tell the difference? Based the results found in a paper authored by Demian Willette, an instructor in the Department of Biology in the Frank R. Seaver College of Science and Engineering, it may be important to learn. He and his colleagues during his stint at UCLA conducted a study of species substitution in which students visited more than two dozen sushi restaurants in Los Angeles to see if sushi in dishes they purchased was the same fish species advertised on the menu. They found that 47 percent of the samples they collected were mislabeled. The consequences can be serious in terms of economic costs. People with allergies could unknowingly consume fish they must avoid. And if environmentally threatened fish are being substituted for more plentiful species, there are implications for conservation efforts. We spoke to Willette about his research and some of those issues. He was interviewed by Editor Joseph Wakelee-Lynch. How does species substitution occur? At the consumer end of the supply chain, there is either intentional substitution — switching a less valuable fish for a more valuable one, such as substituting tuna with tilapia. Or you think you’re buying bluefin tuna and it ends up being skipjack tuna, a less valuable tuna, or albacore tuna, which is more abundant. That switching can also be accidental. At the other end of the supply chain, things are being swapped through labeling on the box: The label on the fish is different from what’s actually being delivered. Traceability is very difficult. These fish are caught in the ocean, they can move from boat to boat before they get to the port; if it’s not a U.S. port they can be shipped around the world. In this supply chain, the paperwork and invoices can be lost. You can also have accidental mislabeling due to translation. An example of this involves red snapper. In the United States, the FDA [Food and Drug Administration] says that one species of fish, lutjanus campechanus, is the only fish that you can call red snapper. However, in Japan the fish that is associated with “red snapper” is different — Pagrus major or red sea bream. The one we call red snapper is from the Caribbean. In Japan, you wouldn’t have a red snapper fish from the Caribbean; that fish is actually from the Pacific. How significant are the economic costs of species substitution? It’s called illegal unreported and unregulated fishing — IUU fishing — and it has an estimated cost to the fishing industry of $10 to $23 billion a year. How did you acquire the fish samples that you tested for your study? From 2012–15, a colleague and I taught a marine science class at UCLA. In the year before I started, the teaching assistant, Sara Simmonds, began this study as a class project with the students. They targeted eight fish and went to highly rated restaurants found on Yelp and Zagat. Students went with forceps and small test tubes about 1 inch long containing ethanol. They took a photo of the menu, ordered the fish, put a piece the size of a corn kernel in the test tube, brought it back to the lab and did DNA-sequencing. When I came to UCLA in 2012, I said, “Let’s do it again to compare results.” We did that again the following year. And in the third year, we began to see a consistent pattern and decided to try to publish the results. Was the practice of mislabeling more common in high-end restaurants than in moderately priced restaurants? The restaurants weren’t selected based on cost but based on Yelp and Zagat ratings. We had everything from stand-alone, mom-and-pop restaurants to chains. We did collect price data, but we didn’t publish that because there were discrepancies in how students were taking the data. There has been some interest expressed in looking specifically at high-end restaurants to see if mislabeling is common there, because you might assume that they would trace their food better. However, we sampled 26 restaurants — that’s roughly 10 percent of the sushi restaurants in L.A. — and all of them had at least one case of mislabeling, and some were high-end restaurants. If your study were replicated elsewhere, do you think the results would be similar to those for Los Angeles? I can tell you that in 2015, a study looked at New York, Austin, Texas, and San Francisco. There were comparable rates of mislabeling among those three locations. Their rates were lower than ours, and they did only one year of data-collecting. Our paper has a table with data from around the world. On average, the European mislabeling rates, for example, are lower than those for cities in the U.S. that have been studied. As for why, there may be differences in where the fish come from. In the U.S., 90 percent of the fish are imported. In the European Union, fish are imported into the countries but often they come from other E.U. countries that share the same regulations. So the traceability may be better; we hypothesize that that may be the explanation. But based on the studies that have been done, I think this is a very pervasive problem. Has the U.S. government taken actions to deal with mislabeling? Yes, the Seafood Import Monitoring Program was developed during the Obama administration. It was released by NOAA (National Oceanic and Atmospheric Administration) Fisheries and became effective this past January 9, two days before we released our paper. The law applies to certain fish and fish products; from wherever the fish is caught to the U.S. border you have to show traceability, a paper trail from the ship to the border. There already exists a law known as COOL (Country of Origin Labeling) that applies from the U.S. border to the vendor. So, moving forward, it will be more possible to see if the rate of mislabeling drops, because now we have a comprehensive system of traceability. A few days ago, I received a Fulbright that will allow me to study traceability of fish for next two summers in the Philippines, Ecuador and Thailand, which are among the worst in the world in illegal fishing. Imagine that this coming weekend a friend says to you, “Let’s go out and get some sushi.” Based on what you’ve learned, can you pick a restaurant and be confident that what you’ll order is what you’ll get? No. I know which fish I would order, and I know which ones I would avoid. I wouldn’t order halibut, unless I don’t care and just want to eat fish. Do I taste the difference? No.