A global strategy to combat cetacean and other marine megafauna bycatch in the growing trade for fish maw (swim bladders)
As previously reported (see our 2023 article: Escalating threat to marine wildlife from trade demand for croaker fish swim bladders), the IUCN Cetacean Specialist Group has a long history of engagement in efforts to save the vaquita porpoise (Phocoena sinus) from extinction due to bycatch in gillnets targeting the totoaba croaker (Totoaba macdonaldi) for its maw (swim bladder). Similar to shark fins, larger maws—particularly from croakers—are in high demand, primarily in China, as a luxury or status food and as a financial investment, while smaller maws are ground into powder for purported medicinal and cosmetic uses.
As restrictions on international trade in shark products under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) have reduced the availability of shark fins, maw is increasingly sought as an alternative. Imports of dried maws to Hong Kong alone are now valued at approximately US$280 million annually, with individual large maws fetching thousands of dollars at the point of capture. This growing “gold rush” has transformed fisheries that once treated maw as a by-product into targeted operations, with fishers often discarding the carcass and retaining only the maw. The resulting increase in fishing effort, particularly in coastal and estuarine habitats where croakers aggregate, has significantly elevated bycatch risk for already threatened small cetaceans and other marine megafauna, including sharks, rays and marine turtles, sharing these areas. Impacted small cetacean species include the Irrawaddy dolphin (Orcaella brevirostris), Indo-Pacific humpback dolphin (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) in South and Southeast Asia, as well as snubfin (Orcaella heinsoni) and humpback dolphins (Sousa sahulensis) in Papua New Guinea.
Endangered Irrawaddy dolphin caught in gillnet that catches Blackspotted croakers
Fisheries targeting maw frequently operate with limited monitoring or management, often involve illegal, unreported and unregulated (IUU) fishing, and are attracting the interest of organized criminals. These are all issues which, in addition to sustainability, must be addressed at the domestic level in each country. But multilateral environmental agreements, including the Convention on the Conservation of Migratory Species of Wild Animals (CMS) and CITES, which can regulate the take and trade of fish maw, have a vital role to play. The CSG has been collaborating with other IUCN specialist groups and NGOs to support a wide-reaching strategy to raise awareness of the impact of the maw trade, and identify action that needs to be taken. The CSG provides expert technical advice on this strategy, which includes targeted engagement and preparation for IGO meetings, including CITES, CMS and International Whaling Commission (IWC), where decisions can help to improve awareness, monitoring and, most importantly, mitigation of bycatch related to maw fisheries.
Most recently, the CSG contributed to a side event at the March 2026 CMS Conference of Parties. Collaborating NGOs prepared a briefing document, and the CSG contributed to the event with a presentation on the impacts of the maw trade on cetaceans (insert photos here). During the meeting, CMS Parties adopted a resolution and decisions recognizing the maw trade as an emerging issue of concern and establishing collaboration with CITES and the IWC to address its impacts. This provides an important foundation for the coordinated international action that is needed, including improved trade monitoring and the development of targeted mitigation strategies to reduce bycatch of small cetaceans.
Alex cetacean presentation at side event
Alex at side event
To strengthen the evidence base for this international action, the CSG has circulated an online survey to its members to better understand the links between demand for croaker maws and fisheries that incidentally capture small cetaceans. The results will help detect bycatch hotspots, inform domestic and international conservation priorities, and identify target species that may benefit from regulation under CMS and CITES. If this approach proves useful and informative, it is hoped that a similar approach will be adopted by other IUCN Specialist Groups to support a comprehensive and coordinated response to the impacts of the global maw trade.