DNA barcoding of Mobulid Ray Gill Rakers for Implementing CITES on Elasmobranch in China

Abstract

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) has been counted on for conserving threatened marine fish since it regulates the commercial international trade of these species. Implementation of the international treaty for Mantas included on CITES Appendix II is challenging due to insufficient information on species identification and markets management. To fill the gap in such aspects, we identified five species of Mobulid rays (Mobula spps. and Manta spp) by using COI and NADH2 mtDNA markers in dried ray gill rakers from Chinese markets, namely, Mobula japonica (representing 54.8% of the sample set), M. tarapacana (14.4%), M. kuhlii (13.3%), M. thurstoni (6.4%), along with Manta birostris (11.2%; CITES Appendix II). The utilization and conservation statuses of these species were discussed. Based on combination of DNA barcodes and key morphological characters, we developed a three-step process for identifying the gill rakers of Mobulid rays which has been adopted by frontline enforcement in China. We hope that our work can serve as a foundation and basis to reinforce objectives of international treaties, regulation of consumer-driven markets, regional cooperation, and national fishery management on endangered elasmobranchs in China as well as related countries.

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

“…In a study of 188 market-derived gill plates from southern China, Zeng et al . 4 also reported the occurrence gills from the genus Manta (11.2% of samples). However, they also were unable to distinguish between the two known Manta species based on COI barcodes, nor mitochondrial NADH2 gene sequences, and chose to assign their products to Manta birostris .…”

“…Elasmobranch meat is an important source of protein in many coastal communities. However, 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 – 4 .…”

“…The CITES listing requires international trade in these species to be highly regulated, including an assessment by the exporting country that the trade will not be detrimental to wild populations of the species 15 . Given a paucity of trade records, in part because of species identification difficulties, the relative contribution of each of the nine devil ray species to the global gill plate trade requires further investigation 4 .…”

“…Over the past few decades, molecular techniques have been proposed for elasmobranch species identification, particularly in instances when traditional taxonomic methods fail 17 – 22 . DNA barcoding has been established as a powerful tool for fish species identification 23 , 24 , and several studies have successfully barcoded sharks and rays 25 , 26 , as well as processed material 4 , 27 – 31 . As of February 2017, some 670 of the known 1200 elasmobranch species have been barcoded.…”

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“…Mobula'kuhlii!!and!~USD$350!for!M. 'birostris'in!China' (Zeng!et!al.,!2016).!Mobulids!are!also! taken!as!bycatch,!particularly!in!driftnets!and!purseJseine!nets!targeting!tuna!…”