DNA analysis of traded shark fins and mobulid gill plates reveals a high proportion of species of conservation concern

Dirk Steinke,Rebekah L. Horn,Robert Hanner,Andrea M. Bernard,Paul Hilton,Mahmood S. Shivji

doi:10.1038/s41598-017-10123-5

Dirk Steinke, Rebekah L. Horn + Show 4 more

Open Access

https://doi.org/10.1038/s41598-017-10123-5

Copy DOI

Abstract

Continuously increasing demand for plant and animal products causes unsustainable depletion of biological resources. It is estimated that one-quarter of sharks and rays are threatened worldwide and although the global fin trade is widely recognized as a major driver, demand for meat, liver oil, and gill plates also represents a significant threat. This study used DNA barcoding and 16 S rRNA sequencing as a method to identify shark and ray species from dried fins and gill plates, obtained in Canada, China, and Sri Lanka. 129 fins and gill plates were analysed and searches on BOLD produced matches to 20 species of sharks and five species of rays or – in two cases – to a species pair. Twelve of the species found are listed or have been approved for listing in 2017 in the appendices of the Convention on International Trade in Endangered Species of Fauna and Flora (CITES), including the whale shark (Rhincodon typus), which was surprisingly found among both shark fin and gill plate samples. More than half of identified species fall under the IUCN Red List categories ‘Endangered’ and ‘Vulnerable’, raising further concerns about the impacts of this trade on the sustainability of these low productivity species.

Highlights

Good quality COI barcode sequences were obtained for all 71 dried shark fin samples and 53 of the 58 dried gill plate samples, with sequence lengths varying between 93 and 664 bp
For the five remaining dried gill plates good quality sequences were obtained via 16 S rRNA sequencing; these 16 S sequences varied in length between 505–514 bp
We identified 129 commercial samples using the Barcode of Life Datasystems (BOLD) “species-level” identification tool to query sample barcodes against the BOLD reference database or using National Center for Biotechnology Information (NCBI)’s Basic Local Alignment Search Tool (BLAST) tool, which provided a sequence similarity value greater than 99% in all cases, despite considerable length differences of the query sequences

Summary

Introduction

It is estimated that one-quarter of sharks and rays are threatened worldwide and the global fin trade is widely recognized as a major driver, demand for meat, liver oil, and gill plates represents a significant threat. High demand for their fins to make soup, a celebratory dish in some Asian cuisines, and more recently, for the prebranchial appendages or gill plates (rakers) of mobulid rays (Family Mobulidae) for medicinal purposes is driving the unsustainable exploitation of these vulnerable fishes[1,2,3,4]. Sharks sourced for fins and mobulid rays for gill plates come from various sources such as legal fisheries, by-catch, and illegal, unreported and unregulated (IUU) fisheries. Population declines of 56–86% for mobulids have been reported over the past 6–8 years in key range countries such as Indonesia and Mozambique resulting from increased exploitation and habitat destruction[5, 7,8,9,10]

Methods

Results

Conclusion