Chondrichthyans are cartilaginous fishes including sharks, rays, and chimeras. They are some of the most threatened vertebrates in existence, according to the International Union for the Conservation of Nature (IUCN). In fact, research shows that more than one-third of all chondrichthyans are now threatened with extinction. The leading cause of this threat is unsustainable fishing. But what leads to unsustainable fishing?

Chondrichthyans are consumed as food or traded as high-value export products, for instance as dried fins. In this study, researchers propose that the international trading of chondrichthyans as high-value products may be a driver of unsustainable fishing. To that end, they purchased shark fin trimmings over multiple years from fish vendors in Hong Kong to identify the species being sold. They hypothesized that if international trade is driving unsustainable fishing, then threatened species would be traded at disproportionately high levels (compared to non-threatened species). Besides this hypothesis, the researchers also investigated whether any of the identified species were managed or regulated. 

From 2014-2018,  the researchers purchased and identified about ten thousand fin trimmings. They detected a total of 86 different chondrichthyan species and checked the extinction status of each of them. Of the 86 species that the researchers identified, 61 (71%) are listed as threatened with extinction by the IUCN Red List. The most frequently identified species was the blue shark (Prionace glauca), which is listed as Near Threatened. Of the top 10 most identified species, the remaining nine were classified as Threatened. 

Only a very small number of species identified in this study were under a trade prohibition or considered “sustainably managed.” Even when certain populations of threatened species are managed or regulated, such protection is not always global. For instance, the populations of some coastal species such as the sandbar shark or the milk shark are actively being managed in certain nations such as the U.S., Australia, and New Zealand. However, the populations of the same coastal species that occur outside of these high-capacity nations are not managed. Regionally, these coastal species are still under the threat of extinction. 

The researchers also suggest that species who live in unregulated regions (e.g., smalltail sharks or broadfin sharks) are likely to face broad regional extinction. That’s why they call for global trade regulations or methods to improve local management practices. An example of a local management approach is applying a limit-based catch management system to make sure that certain species are not fished disproportionately. They argue that even improvements on a limited local scale can play a role in conserving these animals. 

The researchers identified a disproportionately high number of species with fins that are highly valued in international trade. This, however, does not mean that species with low-value fins are not in danger. In fact, they suggest that being classified as “low value”  may drive fishing at a larger scale to increase profits by selling larger quantities of a given fin. Thus, focusing conservation or regulation efforts only on highly sought-after species may put other threatened species in more danger. 

Based on their findings, the researchers suggest that international trade may indeed be the ultimate threat to sharks, rays, and chimera species. Imposing trade regulations can help with conservation efforts, but they also suggest opportunities for low-capacity nations. If setting up marine protected areas isn’t an option, countries should consider catch limits combined with fishing gear modifications to prevent accidental harm caused to chondrichthyans. In addition to calling for these changes, animal advocates should continue to work with consumers to reduce shark fin consumption.