Threatening the endangered: Uncovering endangered elasmobranchs and factors perpetuating the Tanzanian shark-fin trade

Despite global conservation efforts, elasmobranchs still face increased fishing pressure due to high demand for their products. Although certain species have been afforded international and local protection, the high value of their products in international markets incentivises the trade of protected species covertly within marketed fish products. To address the problem, we amplified fragments of the cytochrome oxidase subunit I gene (approximately 595 base pairs) from 164 elasmobranch fins collected from fish markets in Tanzania to test whether protected species and those of conservation concern are among these specimens. Similarly, we conducted 130 in-depth key informant interviews with stakeholders involved in the elasmobranch-fin trade to gather diverse perspectives on the factors perpetuating the trade. Our findings revealed fifteen elasmobranch species, with requiem sharks (Carcharhinidae) and wedgefishes (Rhinidae) accounting for 44.1% and 33.8% of the fins, respectively. Alarmingly, over 70% of the traded fins originated from threatened elasmobranchs, with 36.8% sourced from critically endangered species. Unexpectedly, almost 9% of the traded fins were sourced from two nationally protected species, Carcharhinus longimanus and Alopias pelagicus, highlighting the existence of regulatory gaps that require immediate attention. Similarly, 91.2% of traded fins were sourced from CITES-listed species, emphasising the severity of the problem. The interviews highlighted technological challenges in tracking the trade, limited awareness of trade impacts on elasmobranch sustainability, scarce surveillance resources, inadequate training to identify routes and offenders and lack of public support as the main factors perpetuating the trade. Addressing these issues necessitates a total ban on elasmobranch-fin trade, coupled with increased funding for enforcement agencies, providing specialised training for law enforcement personnel, launching public awareness campaigns and promoting community-based monitoring and collaboration with international organisations. By doing so, Tanzania can effectively safeguard the sustainability of threatened elasmobranchs and advance global conservation efforts for these fishes.