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

Abstract

We identified shark fins sampled across the entirety of a shark fin shop that had operated on the west coast of the United States until 2014. From these specimens we obtained 963 species identifications with Cytochrome oxidase (COI) sequencing and 1,720 identifications with control region (CR) sequences. We found 36-39 distinct species with COI and 38-41 with CR. Of the species identified, 16-23 are currently listed as Endangered or Vulnerable on the IUCN Red List, an additional 2 are considered data deficient, and 7 currently listed under CITES Appendix II. Of the 2.5 tonnes of fins from this collection, we estimated 56-66% (CR or COI, respectively) come from CITES-listed species or those the IUCN considers threatened or data deficient. Most of these species occur outside of the United States EEZ, comprising a global set of species that is common in most fin surveys. The principal target shark fishery in the United States (spiny dogfish; Squalus acanthias) has no fins in our collection. Fins seen abundantly in our collection include pelagic species such as thresher, mako, oceanic whitetip, silky, blue and hammerhead sharks, as in previous samples of the shark fin supply chain. However, in addition, we see a large flood of blacktip, dusky, sandbar, and smalltail sharks that are common in shallow coastal waters. This may indicate that the global market for shark fins takes sharks from nearshore coastal zones, all over the world. Abundant species in the fin shop included globally-distributed species such as scalloped hammerheads and shortfin mako sharks, but also regionally-restricted species such as finetooth, blacknose, and Caribbean Reef sharks found only in the western Atlantic or Caribbean. Specimens identified from rare species of particular conservation concern included the wedgefish genus Rhyncobatus and the white shark. Both molecular markers performed well in identifying most fins, achieving a similar degree of taxonomic certainty. The universal primers for COI regularly amplified bacteria in wet fin samples, but the CR primers were able to return shark sequences even from these degraded samples. However, the CR primers amplified a second gene, likely a pseudogene, in some important and abundant species, and seriously underestimated some species of high conversation concern such as the thresher sharks.