DNA-based identification reveals illegal trade of threatened shark species in a global elasmobranch conservation hotspot

Abstract

Here, we report trading of endangered shark species in a world hotspot for elasmobranch conservation in Brazil. Data on shark fisheries are scarce in Brazil, although the northern and northeastern regions have the highest indices of shark bycatch. Harvest is made primarily with processed carcasses lacking head and fins, which hampers reliable species identification and law enforcement on illegal catches. We used partial sequences of two mitochondrial genes (COI and/or NADH2) to identify 17 shark species from 427 samples being harvested and marketed on the northern coast of Brazil. Nine species (53%) are listed under some extinction threat category according to Brazilian law and international authorities (IUCN – International Union for Conservation of Nature; CITES – Convention on International Trade of Endangered Species of Wild Fauna and Flora). The number increases to 13 (76%) if we also consider the Near Threatened category. Hammerhead sharks are under threat worldwide, and composed 18.7% of samples, with Sphyrna mokarran being the fourth most common species among samples. As illegal trade of threatened shark species is a worldwide conservation problem, molecular identification of processed meat or specimens lacking diagnostic body parts is a highly effective tool for species identification and law enforcement.

DNA analysis of a large collection of shark fins from a US retail shop: species composition, global extent of trade and conservation - a Technical Report from the Monterey Bay Aquarium

“…Our data bolster several recent retail market surveys that have also concluded that the shark fin market is highly diverse and highly endangered (Cardeñosa et al, 2018; Feitosa et al, 2018; Fields et al, 2018; Steinke et al, 2017). Steinke et al (2017) found 20 species in 72 shark samples from Vancouver, Canada.…”

“…Similarly, Cardeñosa et al (2018) found 82 species and species complexes in Hong Kong among small fin discards in 2016. Feitosa et al (2018) found 17 predominantly nearshore species from 427 fin samples collected in northeastern Brazil. In these cases, and the samples reported here, some similarities emerge.…”

“…The relatively lower number of blue shark fins in retail markets on the US west coast may partially answer this question if there is a strong regional difference in market availability of this species. No blue sharks occur in the Brazil samples, which is dominated by regional sharpnose and Carcharhinus species (Feitosa et al, 2018).…”

“…But coastal species have increasingly been observed. Recently, effort has shifted to tests of retail outlets that likely integrate supply chains over months or years (Cardeñosa et al, 2018; Feitosa et al, 2018; Fields et al, 2018). For example, Fields et al (2018) surveyed 92 retail markets in Hong Kong in 2014-2015 and processed 3,800 samples with a small piece of the COI gene, identifying them to the species level.…”

“…Cardeñosa et al (2018) extended this survey to a total of 9,200 samples between 2014-2016 with 80% identification rate totaling 82 species or complexes. Feitosa et al (2018) surveyed several retail fish markets in northern Brazil from 2014-2016, and from government inspections obtained in 2007, identifying 17 mostly regional and coastally-distributed species from 427 fins. In other cases, reliance on relatively small data sets [ n =72 in (Steinke et al, 2017)] may not show the complete spectrum of commercial species.…”