Emerging from the murk: threats, challenges and opportunities for the global swim bladder trade

Fish maw, or swim bladder, has long been used as food and medicine in Asia, particularly in southern China. Considering its history as luxury and nutritious seafood, surprisingly little information on volumes, values, source of maw or species composition involved in the trade is available. In 2015, Hong Kong, the global trade hub for maw, introduced a ‘maw’ commodity code enabling a first global look at its trade. This study finds that 3144–3882 t of dried fish maw was imported annually to Hong Kong from 2015 to 2018, coming from about 110 countries/territories, with a declared import value of 264–394 million USD. These volumes and values, similar to those of the better-known sea cucumber and shark fin trades, highlight the growing importance of maw. Prices can involve massive mark-ups, with investment speculation associated with the most valuable maw categories. Similar volumes to those imported are re-exported annually, mostly to Vietnam. By volume, 50% of maw came from Uganda, Brazil, Tanzania, India and Vietnam. Species composition was dominated by croakers ( Sciaenidae ), with Lates perch ( Latidae ), pufferfish ( Tetraodontidae ), various catfish ( Siluriformes ) and pike conger ( Muraenesocidae ) also traded, among other species. This lucrative trade has two components, high value maw and cheaper maw for regular consumption, and is expanding into new markets, such as shark fin substitution. There is loose association between trade category and species which can lead to confusion for consumers. Considering possible threats to biodiversity and evidence of illegal and secretive trade, management is called for to harness benefits and reduce risks.