## Introduction

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is a binding and multilateral environmental agreement with the objective of prohibiting trade of wildlife species in immediate danger of extinction (Appendix I listing) and preventing additional threatened species reaching this critical stage by regulating trade so that it is traceable, legal, and sustainable (Appendix II listing). CITES is the first line of defense against illegal wildlife trafficking, with 183 parties (i.e. signatory nations), and lists over 35,000 animal and plant species1. The vast majority of these species (96%) are listed in Appendix II and exporting parties have the obligation to document that traded specimens are traceable through the supply chain, were legally obtained, and that trade it is not detrimental for the survival of the species2. Importing parties are required to monitor imports and certify that incoming specimens are accompanied by the appropriate documentation2. Failure to properly implement CITES for any listed species can eventually lead to international trade sanctions being placed on offending parties2.

Sharks are a group of marine fish many of which are threatened by overexploitation to satisfy demand for internationally traded products, primarily fins (for use in luxury Asian soup dishes) and meat3,4. Twelve shark species have been listed in CITES Appendix II to date. The first round of shark listings took place from 2001–2004, with the whale shark Rhincodon typus (2001), basking shark Cetorhinus maximus (2001), and great white shark Carcharodon carcharias (2004). These species all share the characteristics of being iconic, extremely large bodied (>4.0 m total length at maturity), and some products from these species (e.g., fins, dressed carcasses) can be readily identified by their very large sizes (except when procured from juvenile stages) or other morphological features (e.g., jaws and teeth for great whites). These species also share the characteristic that Appendix II listing is not as stringent as the domestic protection these species receive in many jurisdictions (i.e., landing and trade prohibition4,5). Products of these species have generally not been detected in post-listing studies of major shark fin and meat markets, suggesting they are rare in trade6,7,8,9,10.