As the shark fin trade wanes, we need to curb the roaring trade of rhino ray fins

I still vividly remember my first walk through the Sheung Wan district of Hong Kong in late 2013, the dried seafood part of this port city. I saw fins from tens of thousands of sharks that day, with each shop packed fuller than the last and some even displaying fins out into the street. The pungent smell of fins permeated the air, and it was clear that this handful of city blocks was the terminus of a vast and unfettered flow of fins from all over the world. To be sure, there were other dried seafood products on sale. But the shark fins were the product that dominated the scene. I probably saw more ‘sharks’ in those few hours than I had seen live sharks for years working at sea.

The Sheung Wan district of Hong Kong is likely the world’s largest shark fin retail market and has been the epicentre of the trade for decades. Photo © Demian Chapman

My team has been working in Hong Kong for over a decade now, and as part of our Save Our Seas funded project ‘DNA testing for Rhino Rays’ I visited the market again in late 2023. The neighbourhood looked pretty much the same as it did years ago, but I was struck by how much the trade in shark fins had receded. Sure, there were fins in nearly every shop, but now for the most part they were just one of several products. If anything, it seemed that fish maw, the swim bladders of bony fish, adorned every shop window like golden balloons while shark fins were tucked away on the back shelves. I knew from my collaborator and friend Stan Shea from Bloom Association’s work looking at fin import records that Hong Kong’s primacy in the fin trade had been waning over time, but I wasn’t expecting the difference to be so stark. My taxi driver had given me a hint, though. He told me that sharks were endangered and their fins were prohibited – missing much of the nuance about the actual legal status of shark imports – but illustrating that a sea change is afoot.

Rhino ray fins for sale in Hong Kong retail market. Photo © Demian Chapman

What is driving the change? Almost certainly it is a preponderance of things: increasing public awareness, reduced demand for fin soup, and an anti-corruption drive leading to fin soup being avoided for official functions. Trade has also likely been affected by the listing of over two thirds of the shark species involved on Appendix II of the Convention on International Trade of Endangered Species (CITES), which makes importing shark fins more complicated than some other products. The reason I am visiting Hong Kong is to help the Agriculture Fisheries & Conservation Department (AFCD) upgrade their DNA testing capacity, which thanks to Dr. Diego Cardenosa from Florida International University is keeping pace with the rapid expansion of listed shark species they need to test for if a fin shipment comes in without CITES documents. AFCD has seized hundreds of tons of shark fins at the border without CITES permits and prosecuted the importers. But it wasn’t shark fins I had returned to Hong Kong to help AFCD hunt for.

A 'rhino ray' fin. Photo © Demian Chapman

It sounds like a bad joke- ‘waiter, there is a ray in my shark fin soup’, but many people are surprised to hear that the fins of some of the shark-like rays – the wedgefish and giant guitarfish or “rhino rays” – are the most valuable ‘shark’ fins in the market. The internal support structures of the fin, called ceratotrichia, form the noodles of the soup and give it the desired texture. Rhino ray ceratotrichia have a unique texture and ‘mouthfeel’ that are especially sought after, and their large, tall fins fetch premium prices. These species are often caught alive in various net and line fisheries operating in coastal areas and the fin export value has prompted fishers to keep them. As a result, nearly all rhino rays are critically endangered. Convincing fishers release them when caught will be key to rhino ray recovery – a tricky proposition when the fins, especially from large ones, are so valuable. CITES could create barriers to export markets unless landings are fully documented and certified as being sustainable. A loss of fin export potential might just lower the value of rhino rays enough that fishers could be more easily convinced to release them or avoid catching them in the first place. With this goal in mind, all rhino rays were listed on CITES starting in 2020. At the end of 2025, CITES Parties may also add a zero quota for these species, a temporary global ban of international trade.

Valerie Hagan Shark Program Coordinator at Mote Marine Laboratory & Aquarium teaches Agriculture Fisheries and Conservation Department (AFCD) personnel how to use new PCR thermal cycler to identify shark and ray fins. Photo © Demian Chapman

CITES listing is a step towards conservation, but only a step. One potential issue is that fin traders might try to smuggle premium rhino ray fins in shipments containing shark fins, but without the required ray export permits. My team has been monitoring the species composition of the fin trade since 2014 and we have found no change in the occurrence of rhino rays before and after the CITES listing, which we interpret to mean that the ray fin market is being sustained by illegal trade. So, this is how Stan and I find ourselves in the dried seafood district hunting for rays. Our goal was to build up our rhino ray sample library as we worked with Diego to develop a PCR test that could differentiate ray fins from shark fins, thus giving AFCD a new tool in their arsenal. Although the shark fin trade is greatly diminished it didn’t take us long to find a stack of rhino ray fins in a shop, the conspicuous white polka dots telling us they were from a bowmouth guitarfish (Rhina anclystomus). We paid a small fortune for one of these fins, taking it back to the lab to subject it to the putative ray PCR test. Diego’s primer design skills did not disappoint and within a few weeks we have a working test and AFCD has a new real time thermal cycler to run it in thanks to the Save Our Seas Foundation.

AFCD is used to catching rhino horn smugglers and will now use their new PCR thermal cycler to catch rhino ray fin smugglers. Photo © Demian Chapman

Does this PCR test give me hope for rhino rays? Yes, but not in isolation. It will certainly be used to detect and help deter illegal trade as rhino ray fins cross borders, which is inarguably a major driver of rhino ray decline. Many fin traders may eventually quit buying rhino ray fins if the risk of importing them is too great. But we have to think of the fishers who will have to make the decision to release or retain these rhino rays. We are asking a lot of them- to lose or forgo a catch that may have fed their family for weeks or months when they could sell the fins. I am hopeful, however, when I hear about people who are working with these fishing communities to incentivise rhino ray release or helping these communities move away from destructive fishing practices in general – the ‘carrot’ to the CITES ‘stick’. Effectively implemented CITES listing can surely drive the economic value of rhino rays down, but it is equally important to ensure fishers are still able to make a living without killing these rays. At the end of the day, rhino ray conservation will be affected by what happens at the border, but it will be won – or lost – by people’s decisions on the water. The sea change on shark fins in Hong Kong we have seen in the last decade gives me some hope that we may eventually see a similar change for rhino ray fins.