A stroll through a Chinese street market offers a glimpse into centuries-old traditions, showcasing jars and pouches filled with herbs, spices, medicinal ingredients, and even dried seahorses and fish. Among these, swimming bladders—known as the “cocaine of the seas”—have become a prized item on display.

But why has this particular anatomical feature, found in select fish, surged in demand and threatened ecological devastation?

According to a report published in Nature, demand for the swimming bladder—a vital organ helping fish maintain buoyancy—has skyrocketed, so much so that it has earned the nickname “cocaine of the seas,” as its profitability has attracted organized crime. Typically found in sturgeon, the bladder is a culinary delicacy in Chinese cuisine, as well as a source of collagen, protein, and nutrients. It is believed to strengthen the kidneys, improve vitality, and benefit those with respiratory or anemia issues. Its medicinal value has driven prices up to $15,000 per kilogram for species like Nibea squamosa.

In Papua New Guinea, fishing for these prized fish has become so profitable that local fishermen have traded canoes and fishing rods for motorized boats and nets to ensure larger catches.

Yet, overfishing poses severe consequences for marine ecosystems. Unselective fishing methods capture various species, including dolphins and sea turtles, while other species lose essential food sources, potentially disrupting entire ecosystems.

In the past, Mexico banned fishing for Totoaba macdonaldi in the Gulf of Mexico due to overharvesting for the valuable bladder. However, illegal fishing and online trafficking continue, as documented in a report by the Environmental Investigation Agency (EIA) last February, showing platforms like WeChat facilitating trade despite the ban.

“Fishing has helped alleviate significant poverty issues,” marine biologist Michael Grant from James Cook University in Townsville, Australia, explains. Grant, who studies sharks and rays in Papua New Guinea’s Kikori Delta, one of the last of their habitats, warns that the surge in bladder fishing could threaten local ecosystems and people reliant on these marine species for food and income.

The International Union for Conservation of Nature (IUCN) recently raised alarms about the growing trade at the July meeting of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). According to reports, two endemic dolphin species, classified as vulnerable by the IUCN, are among the victims of this trade, putting their populations at risk.

Despite these environmental threats, local fishing activity remains robust due to substantial profits, as reported by Nature. “Local fishermen acknowledge sustainability concerns, but overall, everyone seems pleased for now,” Grant notes, adding, “The next step will be studying whether these profits will reinvest in community development.”