The documentation of mislabeling has raised concern over the identity, value, and safety of seafood. A new study characterizes seafood fraud globally and estimates, for the first time, mislabeling rates and their uncertainty for a variety of products. By analyzing >27,000 samples that have been tested for mislabeling, the study demonstrates that for most seafood products mislabeling rates are lower than commonly reported. It also confirms that some products have high rates.

Published in Biological Conservation, the authors use statistical modeling to show that the commonly reported mislabeling rate of ~30% is an inaccurate representation of seafood fraud. Mislabeling is often being overestimated and the uncertainty of estimates, which is rarely reported, is significant. The study estimates mislabeling for 28 products for which there was sufficient data, producing an overall average rate of 8%. The authors found no differences between countries, in contrast to previous claims that European countries have lower rates due to more progressive seafood policies. At the global level, the study also failed to detect any differences between location or product form. Fish filets were just as likely to be mislabeled as sushi, irrespective if it came from a supermarket or restaurant.

The authors uncovered a number of challenges in characterizing seafood mislabeling. Over half of all products tested have been done so with just five or less samples. “While we documented over 300 studies and 27,000 samples, when effort is broken down by product, sample sizes are frustratingly small: most frequently, a study samples a particular product only once—making it of little utility for estimating mislabeling rates,” explains lead author Gloria Luque. More importantly, it can overestimate mislabeling. Dr. Luque uses a coin toss as an analogy, “It is not uncommon to flip a coin four times and get three tails, but that does not mean the probability of getting a tail is 75%.” Mislabeling rates are most often reported using the average rate of a study, which commonly tests a couple of samples from multiple products. For a variety of reasons, the study average overestimates mislabeling. Some products, however, have high rates—confirming previous research that mislabeling is a concerning issue for certain seafood. This includes Northern Red Snapper, grouper, Common Sole, and European Hake. Yet, more than half of the products included in the study have estimated rates of less than 5%.

This does not mean, however, that seafood mislabeling is not having environmental or economic impacts. Mislabeling estimates must be coupled with other data to understand potential consequences,” explains Josh Donlan, Director of Advanced Conservation Strategies and co-author. “Rates must be viewed through a lens of production. For example, over twice as much Atlantic Cod is eaten every year compared to Pacific salmon. The former is mislabeled less often than the latter, but could be precipitating greater impacts because there is more of it out there being mislabeled.”

Despite an increase in seafood fraud research, little is still known about the topic. For many products that are highly consumed, like shrimp, there are an insufficient number of studies to produce useful estimates of mislabeling rates. Even less is known about the potential environmental and economic impacts. This is partially due to the way studies have been conducted, and this oversimplification has been amplified by the media. The authors show that more research on seafood fraud is sorely needed. The new research is an important first step, explains Dr. Donlan, “Our goal was to provide an accurate characterization of seafood mislabeling, which is a critical first step to investigating the causes and consequences of seafood fraud, as well as designing solutions to reduce it.

Download the paper here.

Luque, G.M. & C.J. Donlan. 2019. The characterization of seafood mislabeling: A global meta-analysis. Biological Conservation.