Is the demand for fish swim bladders driving the extinction of globally endangered marine wildlife?

Abstract

Abstract International trade in croaker swim bladders or maws and incidental catches in fisheries targeting croakers for their maws pose a global problem that needs addressing to protect target croakers and globally threatened small cetaceans, sharks, rays and marine turtles. The lesson of the likely imminent extinction of the vaquita porpoise (Phocoena sinus) in the Gulf of California, Mexico, owing to entanglement in gillnets targeting the totoaba croaker for its maw, is that the underlying threats to marine species must be addressed well before precipitous declines make their extinction inevitable. Opportunistic interviews with fishers and fish traders in Bangladesh indicate that the increasing demand for fish maws, selling for as much as 5,000 USD per kg, may be intensifying small‐scale coastal fisheries and bycatches of globally threatened marine wildlife, especially due to the potential for a windfall profit. In 137 croaker catches made in gillnets, sharks were bycaught in 22%, marine turtles in 8% and rays in 3% of catches. Of particular concern were six bycatches of 125 Critically Endangered scalloped hammerhead sharks (Sphyrna lewini), 11 bycatches of 20 Vulnerable (VU) olive ridley turtles (Lepidochelys olivacea) and two bycatches of 13 VU longtail butterfly rays (Gymnura poecilura). A recent IUCN Motion for ‘Controlling and monitoring trade in croaker swim bladders to protect target croakers and reduce incidental catches of threatened marine megafauna’ recommends conducting an analysis on the impacts of the demand for and trade in fish maws on croaker species and threatened marine megafauna, regulating trade in fish maws through national laws and developing a potential proposal to list croaker species in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). To prevent species extinctions, additional measures focusing on fishery management will be needed.