Singapore's Dried 'Fish Gills' Are Critically Endangered Rays, DNA Reveals

Scientists walked into 20 dried seafood shops and one wholesale vendor across Singapore between February and March 2026 and bought 439 samples of dried gill rakers, the filter-feeding structures sold under labels like "fish gills" or "peng yu sai." Prices ran from about $14 to $470 USD per kilogram, depending on size and perceived quality. Once dried and packaged, the parts lose the physical features used to tell species apart, so the team ran DNA barcoding instead.

Every sample that barcoded successfully belonged to a manta or devil ray. Five species turned up, but two ran the market: the Spinetail Devil Ray (Mobula mobular) and the Sicklefin Devil Ray (Mobula tarapacana), which together accounted for about 80% of identified samples. Across all five species, 84% of successful identifications came from animals classified as Critically Endangered. Twenty-four samples failed to amplify, likely because processing had degraded their DNA.

The paperwork doesn't line up with the shelves. Some products were labelled as coming from India, yet the researchers found no record of gill plate trade between India and Singapore in the international CITES database. Official records show only two permits for commercial trade in mobulid gill rakers involving Singapore between 2016 and 2025. Vague product descriptions, the researchers suggest, help explain the underreporting and make oversight harder — though they don't establish that every undocumented item was deliberately mislabelled.

The study lands just as protections tighten. In March 2026, all ten recognised mobulid species moved to Appendix I of CITES, generally banning their international commercial trade. Previously, confusion between species complicated enforcement; now every mobulid carries the same top-level protection, which could simplify decisions on whether a shipment is legal. The findings give regulators a baseline to measure future changes in Singapore's trade against.

The conservation math is brutal. Females typically birth just one pup every two to five years, so populations can't quickly replace animals taken by fishing, and more than 264,000 mobulid rays are estimated to be caught annually through targeted fisheries and retained bycatch. Some regional populations have dropped by close to 99%. Gill rakers are marketed for circulation, detox and even cancer claims, but there's no credible scientific support — and past research has found arsenic, lead and mercury in mobulid products.