Global food markets further threaten endangered sharks, rays

Roughly half of the world's 1,200 species of sharks and manta rays are listed as threatened by the International Union for Conservation of Nature including 20 that may not be traded internationally.

The study, published today in Scientific Reports, used DNA barcoding technology and found 71 percent of dried fins and gills collected from markets and stores came from species listed as at-risk and banned from international trade. Shark finning, which is removing fins from live sharks, is illegal in Canada.

"Despite the controversy around shark fin soup and the fact that many of these species are threatened there is still a large market for shark fins and a growing demand for ray gill plates," Dirk Steinke, an integrative biology professor and member of the Center for Biodiversity Genomics at the University of Guelph, said in a press release.

"It's an area that until now has been hard to enforce because shark fins are dried and processed before they are sold making it difficult to identify the species."

For the study, researchers collected 129 market samples in China, Canada and Sri Lanka representing 20 sharks and ray species. Whale sharks were included in the samples, which are listed as protected and illegal to trade under the Convention on International Trade in Endangered Species.

DNA barcoding allows scientists to identify species of organisms using genetic material.

"DNA barcoding is an ideal tool when identifying dried samples or samples that have been processed," Steinke said. "It provides enforcement agencies with a method for detecting whether the fins and gills that are being sold are legal or illegal imported species."