Developed by a team of researchers, a new DNA tool is giving sharks new hope in the race against extinction.
By Diego Cardeñosa and Dr. Demian Chapman
Sharks all over the world are threatened by overfishing in the face of demand for products ranging from meat to shark fin soup. Curbing unsustainable trade – trade that is beyond the shark species’ ability to replenish themselves – is an international priority for shark conservation.
The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is an environmental agreement between 183 countries that either prohibits international trade of threatened animals and plants (Appendix I listed species) or mandates that international trade is conducted legally, sustainably, and transparently through an export permit system (Appendix II listed species).
Twelve threatened shark species exploited for their fins, meat, and other products are now listed under CITES Appendix II, which means that countries importing shark products need to check shipments for these shark species and prosecute importers if they don’t have the correct CITES permits. These threatened species include three large hammerhead species, all three threshers, silky, porbeagles, and great whites. The challenge is that sharks are often traded in high volumes and many of their products are visually indistinguishable, meaning that fins, meat, and other products of CITES listed species can be mislabeled as legally traded ones.
Our team at Florida International University, Stony Brook University, and Bloom Association developed a tool that will help customs inspectors all over the world fulfill their role as champions of shark conservation. The tool, funded by Paul G. Allen Family Foundation as part of their ocean health portfolio, is an inexpensive, portable, and rapid DNA protocol that can detect the majority of commonly-traded CITES-listed shark species. The protocol uses small DNA pieces called primers to amplify - or make millions of copies - of a target DNA sequence from one of the target shark species.
When these copies are being made, it causes a dye to be taken into the DNA molecule and fluoresce, which can be detected in a real time thermal-cycler. We combined primers for each of nine CITES-listed sharks into one reaction, enabling us to test processed and unprocessed products for these species in less than 4 hours start-to-finish. Prior to this, the testing could take days and shipments would not be held.
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This approach helps law enforcement officers identify and prosecute illegal trade of these threatened species. Best of all, the tech can be housed at the border and costs less than $1 per sample, meaning that shipments can be inspected inexpensively in near real time. Several shark-trading nations have already shown their interest in this new technique and are now using it.
Notably, this tech can be adapted to detect other types of wildlife as well and so our new goal is to help establish this tech at every border check- point in the world. We look forward to the day when DNA testing wildlife products in transit to becomes as routine as X-raying them. For now we are hopeful that countries trading sharks take this opportunity to enhance their monitoring and enforcement capacity, which will be a critical part of ensuring the continued survival of these ocean predators.