For two decades the standard answer to the shark fin trade has been to regulate the cut. Ban the practice of slicing off fins at sea and dumping the carcass, the theory ran, and the market would shrink behind it. A new study says that is not what happened.
Researchers led by UC Santa Barbara, working with The Nature Conservancy and Renmin University of China, matched shark-finning regulations against trade flows country by country. Their finding, published in Nature Communications, is a null one: finning rules had no statistically significant effect on exports, imports, domestic consumption or the number of trade partners.
"We evaluated a lot of different things and found that there's really no clear-cut answer to our research question," said co-lead author Echelle Burns, a project scientist at UC Santa Barbara's Environmental Markets Lab.
Until recently the question could not be asked at all. Fishery landings data and trade data live in different systems and different units, which makes it near-impossible to follow a fish past the pier or trace a fillet back to an ocean. That changed with the Aquatic Resource Trade in Species dataset, released by the University of Washington in 2024, which tracks fishery products across trade networks and supply chains.
"This research highlights the complex dynamics between fishing practices and trade," said co-lead author Sara Orofino, an ocean scientist at The Nature Conservancy. The two systems, she noted, have traditionally been studied apart because there was no way to connect them.
The method was deliberately conservative. Because countries adopted finning rules at different times, the team compared each country's trade and consumption against its own record before and after adoption, then compared that difference across countries, using nations with no regulations as a control.
What makes the null result interesting is that the plausible outcomes ran in opposite directions. "One idea is that if we prevent shark finning, and fishers decide to stop targeting sharks, then maybe the market for shark products will shrink," Burns explained. The counter-scenario worried researchers just as much. "For example, if a country requires that fishing vessels must land sharks with their fins still attached, the influx of shark meat supply could stimulate a market expansion for shark products," said co-lead author Kaiwen Wang, an economist at Renmin University of China.
Neither showed up in the data.
Senior author Gavin McDonald, a senior project scientist at UCSB's Environmental Markets Lab, was direct about why the team published anyway. "This sort of null result can initially be disappointing for us as researchers," he said. "But it is still incredibly important to share these types of findings. All too often, analyses with null results are abandoned and not shared or published, which can be a huge missed opportunity for advancing science and policy."
Wang read it as a caution rather than an acquittal: "Our findings are an important warning that real-world changes along the supply chain of shark products are much more complicated than we would have thought."
The obvious follow-up question is enforcement, and there separate work has already returned an uncomfortable answer. A Science Advances study led by Dr Diego Cardenosa of Florida International University with Dr Demian Chapman of Mote Marine Laboratory ran DNA analysis on nearly 20,000 shark fin samples from Hong Kong markets collected between 2014 and 2021. Fins from four of the five species listed under CITES in 2013 -- scalloped, smooth and great hammerheads, and oceanic whitetip -- turned up year after year, despite almost no legal certified trade being reported.
"There's a huge gap between what's on paper and what's happening in the real world," Cardenosa said. "DNA evidence clearly shows these protected species are still entering the global market at alarming rates. There are 70 times more fins from oceanic whitetips and 10 times as many hammerhead fins than would be expected based on legal and certified reporting."
"Our findings show that while global trade regulations are a powerful tool, their effectiveness depends on countries actually enforcing them," Chapman said. "We're seeing clear evidence of widespread noncompliance, illegal trade is still happening on a massive scale."
Put the two studies side by side and the picture sharpens. Finning rules, aimed at how a shark is processed, did not move the market. Trade listings, aimed at what crosses a border, are being ignored at scale. The regulatory patchwork -- finning bans, retention bans, gear restrictions, import controls, international trade listings -- is real, overlapping, and apparently far weaker in effect than in intent.
What neither study disputes is the biology underneath. Sharks grow slowly, mature late and produce few young. "Many shark species face extinction because they're frequently caught by fisheries -- sometimes on purpose and sometimes [by] accident," Burns said. Cardenosa framed the stakes without hedging: "We are reaching a major tipping point where if the fishing and trade of these species is not meaningfully reduced, then these sharks will disappear."
