Taking a Closer Look at the Shark Fin Trade
SHOW NOTES
Diego Cardeñosa is an internationally renowned scientist who specialises in using the very tiniest parts of a shark – its DNA – to better understand and combat the illegal trade in endangered shark species. In this episode, we dive deep into the fin trade and explore how molecular biology, forensic genetics, international policy and conservation can work together to tackle one of the greatest threats facing sharks today.
Now an assistant professor at Florida International University, Diego has built a career around conservation genetics. But as a student, this prospect was far from appealing. “I hated genetics in my bachelor’s degree. I absolutely hated it,” he laughs. “Almost failed genetics in my class.” What changed everything was a teacher who focused not just on theory, but how genetics could be used to solve real-world problems. For Diego, who had always harboured a passion for sharks, this was the light-bulb moment that inspired his future: “There are astronomically more papers in telemetry and movement ecology than in genetics. So I could see a route where I could get into the field and make a bigger contribution…to a subject that can improve the conservation of sharks, which is what I love the most since I can remember.” With that ambition driving him, Diego chose a PhD studying the shark fin trade under the supervision of Damien Chapman – and the rest, as we say, is history.
But before diving deeper into Diego’s contributions to the field, it’s important to explain what is meant by the term ‘shark finning’ [16.08]. The specific practice of finning is very different to simply catching and landing a shark; it refers specifically to catching a shark at sea, removing its fins and discarding the rest of its body back into the ocean. Historically, it was a practice driven largely by economics. Fins were extremely valuable, while shark meat was worth comparatively little. With limited storage space on board, fishers saw a more economical way to store as much of the valuable product as possible. “Imagine if you were fishing and you had to fill that space with dead sharks, big sharks,” explains Diego. “…if I take the fins out of the shark and dump the body, I could fill my space with a lot more fins and make a lot more money per trip as a fisherman.” It’s a practice that now is widely seen as cruel, wasteful and unsustainable, and has received a lot of backlash in recent decades; as a result, a lot of countries have now banned the specific practice of finning, and have regulations that specify any sharks fished have to come back to land with their fins naturally attached.
This distinction is important, particularly when photographs and videos circulate online showing sharks being processed at landing sites. “[If] you see them removing the fins, that does not count as finning because the shark has been landed whole,” Diego stresses. The sight may still be uncomfortable, but it represents a different practice — and understanding the difference is crucial when discussing shark fisheries and their management.
Once landed, the fins are then processed for sale [18.39]. They are dried – often in the sun – which allows them to be stored for long periods. Then, the skin and remaining muscle are removed, and for larger fins, they are cut into a more uniform shape. The offcuts from this latter stage, also known as ‘fin trimmings’, have proved incredibly useful to the work of Diego and his colleagues. Whole fins remain a precious commodity, and buying thousands of them for a long-term scientific survey would be prohibitively expensive. Trimmings, however, are comparatively cheap. By sampling them, researchers like Diego can carry out DNA testing to identify which species are being processed and sold without purchasing the entire fin.
That approach has allowed Diego and his colleagues to monitor the species composition of the Hong Kong shark-fin market for more than a decade [28.05]. Among the larger fins and trimmings, blue sharks dominate the market by far, followed by silky sharks, and then blacktip and hammerheads – namely the scalloped hammerhead and smooth hammerhead. But overall, close to 100 species have been found in the trade, many of which are endangered. Furthermore, many species are listed by the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). This means that countries have agreed to certain regulations in the trade of these species, in a commitment to make trade in protected species more traceable, sustainable and legal. Diego’s work has been instrumental in securing more regulations for endangered shark species through CITES, but the fact [that] these species are still appearing in the trade highlights some critical issues in the implementation of these regulations.
One exception is the porbeagle, Lamna nasus [32.38]. Diego has not seen evidence of this species in the trade since 2017 – since it became CITES-listed. He believes the reason for this largely due to their distribution, and the countries that it falls within. “When you see the distribution range of that shark, [where] they’re caught the most is New Zealand, Australia, Canada, US, European Union. Those are high-capacity nations that have some of the best fisheries management regulations that we have around the world…those high-capacity nations are doing their work to CITES in the correct way, that’s why we see a lower contribution, almost undetectable, to the fin trade,” Diego explains.
But the example of the porbeagle seems to be in the minority. Critically Endangered species, like the scalloped hammerhead, are still a common occurrence. There is also another, largely overlooked, problem – the trade in small fins [30.36]. Diego remembers opening a container in Hong Kong that contained a staggering nine tons of fins. When he opened the sacks, the fins were tiny — many smaller than the palm of his hand. And the small fin market tells a different story from the large fin trade. Here, the milk shark (Rhizoprionodon acutus) dominates, and other smaller-bodied sharks also become much more prominent. But even more worrying still is the presence of juvenile sharks, of larger species. These include the Critically Endangered scalloped hammerhead.
“That’s another big problem,” says Diego. “When you start seeing Critically Endangered hammerheads, especially the scalloped hammerhead, in the trimmings as one of the most common, and in the small fins is one of the most common…that means fisheries around the world are hitting almost every aspect of their life histories.” For a species already struggling to recover from severe population declines, that leaves very little breathing room.
And despite major developments in international protection, the overall composition of the fin trade hasn’t changed dramatically over the past decade. It doesn’t mean international agreements like CITES are useless, but it does point towards gaps in implementation and compliance. Getting a species protected on paper is only the beginning: finding workable, sustainable solutions on the ground is the next challenge.
A huge part of the problem was confirming which species of shark a product came from [34.55]. Once they’ve gone through processing, the final product can be very hard to identify at species level; some fins are ‘trimmed’ to a more uniform shape, losing their identifiable characteristics, or may even be turned into a powder. Even the sheer volume of fins coming through can easily overwhelm enforcement officers. Previously, DNA testing would mean sending a sample to a laboratory for genetic analysis. But when you’re standing beside a shipping container filled with thousands of fins, potentially waiting to cross an international border, that isn’t always practical.
So Diego and his colleagues found a way to bring the laboratory to the officials [37.17]. They developed a rapid, portable DNA test that can identify species from processed fins, frozen meat, shark-fin soup and even dried skin. The whole process takes around two hours, costs roughly US$1–1.50 per sample, and the equipment is small enough to travel with Diego on a plane: “Imagine like a toaster kind of size of machine”. The test targets a section of DNA that can be found across all sharks and rays, but which varies enough between species to create a distinctive genetic profile — something Diego describes almost like a signature.
Once that signature has been generated, a machine-learning tool compares it with a growing database of known species and returns the most likely match, along with a confidence score. At the time of the interview, the database contained over 150 species, and the system had an identification accuracy of around 99.2%.
Perhaps the most important aspect of this tool is its portability. The “lab-in-a-backpack” can (and has) travelled everywhere – from inspection facilities beside shipping containers, hotel rooms and other makeshift workspaces around the world. All it really needs is electricity and somewhere sheltered enough to run the machine. “It’s very powerful to be able to take the lab out of the lab and just put it anywhere you want,” says Diego. Since first developing the tool during his PhD, Diego has taken it around the world, training others in how to use it – including the authorities at the shark fin hub of Hong Kong. It now means that an enforcement officer, anywhere, can analyse an unknown animal product, upload the result and rapidly determine what species it came from – a huge step in the right direction.
But after more than a decade studying the shark-fin trade, is Diego seeing any signs that the trade is slowing down [49.24]? In some ways, yes. “We see a decline in the number of fins that are being imported into Hong Kong year after year. So there is a reduction,” he says. “You can argue whether there’s fast enough or not – but there is a change.” But there is still a mountain to tackle. Reducing demand for shark fins requires cultural shifts, and enforcing regulations across an enormous global supply chain remains extremely difficult. At the international level, countries need better implementation and enforcement of existing regulations. “We have the right tools to do this,” Diego stresses. “We just need to improve the implementation to increase compliance.”
There is no easy solution – but there is hope:
“I think one of the signs of hope is…Seeing everybody pulling towards the same goal. And seeing hundreds and hundreds and hundreds of people from all these different countries pulling towards the same goal, using all their knowledge, using all these different tools. I think we’re moving in the right direction.
We need to keep pushing. We need to keep going. But there is momentum, and there’s a lot of us doing good work on our countries and different aspects. So I think if we keep going, we’ll achieve a lot.”
If you want to read more, you can find links to Diego’s research here.
ABOUT OUR GUEST
Diego Cardeñosa is an Assistant Professor at Florida International University (FIU). He uses molecular and forensic tools to fight the illegal trade in endangered sharks, from Hong Kong to Latin America. His latest focus is on understudied small shark fins, many of which are taken from protected species, and he has also proposed a study in coordination with several national governments in Latin America to develop new protocols for interrupting illicit trade in sharks and other species. Dr. Cardeñosa is working in the Predator Ecology and Conservation Lab and supporting the anti-trafficking efforts of the Tropical Conservation Institute and the International Forensic Research Institute. He is also a member of the Explorers Club 50, an organisation that recognises 50 extraordinary people who are doing remarkable work to promote science and exploration.
