Study finds mislabeled shark meat in U.S. stores includes endangered species
University of North Carolina DNA testing of 30 shark products finds nearly one-third from endangered or critically endangered sharks and pervasive ambiguous labeling
A University of North Carolina at Chapel Hill study found that meat sold as "shark" in U.S. retail settings is frequently ambiguously labeled and that nearly one in three tested products came from endangered or critically endangered shark species.
Researchers purchased 30 shark-product samples from grocery stores, Asian markets, seafood markets and online retailers in Washington, D.C., North Carolina, Florida and Georgia and used DNA testing to identify species. The team successfully sequenced 29 of the samples; 27 of those were labeled only as "shark" with no species information. Eleven species were identified among the 29 samples, and four of those — great hammerhead, scalloped hammerhead, tope (school shark) and shortfin mako — are classified as endangered or critically endangered by the International Union for Conservation of Nature (IUCN).
The study, published Tuesday in the journal Frontiers in Marine Science, examined 19 raw shark steaks and 11 packages of shark jelly, a tissue from the pores of a shark's snout that helps detect electric fields. Prices for the sampled products ranged from about $3 per pound to specialty items selling for up to $100 per pound. The researchers noted it was unclear whether any of the samples derived from illegally harvested animals.
Of the species detected, great hammerhead and scalloped hammerhead populations have each declined by more than 80% over the last 70 years, the IUCN has found; some research cited by the authors suggests there may be fewer than 200 individuals of each remaining in some areas. The tope shark population is listed as critically endangered and has fallen roughly 88% over the past 80 years. The shortfin mako is considered endangered, with population declines estimated between 60% and 96% depending on the region.
Other species identified included vulnerable spinner, lemon, common thresher and blacktip sharks, and near-threatened smooth-hound and Pacific angelshark. Only a single sample identified as blacktip shark had a correct species-level label, the authors said.
Lead author Dr. Savannah Ryburn, co-instructor of UNC Chapel Hill's seafood forensics class that conducted the research, said mislabeling removes consumers' ability to choose what they eat. "For example, two species in our study, scalloped hammerhead and great hammerhead, were ambiguously labeled as 'shark,' even though they are strongly advised against consumption due to their very high mercury levels," she said. "Without accurate and precise labeling, consumers cannot avoid purchasing these products."
The authors highlighted public health and ecological consequences tied to the findings. Several hammerhead species tested in the study are known to bioaccumulate mercury, a neurotoxin that can concentrate in brain, kidney and liver tissue. Long-term mercury exposure can lead to mood changes, memory loss, tremors, paralysis and damage to vital organs, according to the researchers. They also underscored the ecological role of sharks as apex predators that help regulate prey populations; unchecked increases in prey can overgraze reefs and deplete other food sources.
Experts have largely attributed steep declines in many shark populations to overfishing, driven in part by demand for fins and meat, combined with sharks' slow reproductive rates and long lifespans that can slow recovery. The study's authors recommended that sellers in the United States be required to provide species-specific names and that consumers avoid products lacking species-level labeling or traceable sourcing when shark meat is not a food-security necessity.
The research adds to growing calls from conservationists and some policymakers for stricter seafood labeling rules and stronger enforcement to prevent trade in at-risk marine species. The study did not assess the legality of individual samples' harvest or sale, and the researchers said additional, larger-scale surveillance would be needed to determine the broader prevalence of mislabeling across the U.S. market.