Fishermen wading barefoot through a writhing ball of venomous serpents can pay a high price for participating in the Gulf of Thailand's (map) sea snake harvest. Some die from snakebites, according to a recent study that suggests the snake catch may be one of the biggest hauls of marine reptiles in the world.

Scientists published estimates of the catch size in the journal Conservation Biology in December, along with some of the first research documenting who's buying and selling sea snakes and the fishery's indirect role in rhino poaching.

Fishermen bitten by their deadly catch believe that drinking ground-up rhino horn—or putting chunks of horn on the wound—can cure them. (See "Why African Rhinos Are Facing a Crisis.")

Some scientists are raising concerns about the practice. Little is known about the region's sea snakes, including what species and how many live there, so it's not clear whether the harvest is sustainable.

An overharvest, these researchers worry, could jeopardize potential medicinal discoveries. Compounds in venom, once processed and administered in controlled amounts, can be beneficial in treating human ailments like heart disease.

The sea snake catch—a side job for the region's Vietnamese squid fishers—takes in over 80 tons (73 metric tons) of the marine reptile annually. That's roughly 225,500 individual sea snakes per year, valued at over $3 million.

The fishery of opportunity occurs during squid hunts conducted each lunar cycle before the moon gets too bright.

Most of the sea snakes end up in China and Vietnam, says the study's lead author Zoltan Takacs, whose work was funded by the National Geographic Society. Restaurants use the meat in soups and employ either the whole animal or just its blood in alcoholic beverages.

The snake's organs, including the heart and gallbladder, play central roles in concoctions meant to relieve maladies such as joint pain, anorexia, and insomnia.

Lost Medicines?

Hunting snakes for food or medicinal purposes is nothing new, says John Murphy, a sea snake researcher at the Field Museum in Chicago. "[And] the Gulf of Thailand harvest seems to be driven by the Chinese market," says the biologist, who was not involved in the study.

Snakes figure prominently in traditional Chinese medicines, Murphy says. Coupled with the country's strong economy, "the demand for snakes—not just sea snakes—is huge." (See why "China's Expanding Middle Class Fuels Poaching, Decadence in Myanmar.")

The demand extends to Western medical practices in other parts of the world, says Takacs, a pharmacologist specializing in animal toxins at ToxinTech in New York City.

"Out of the top three heart attack medications, two of them come from snake venoms," he says.

The potential uses of venoms in the sea snakes in the Gulf of Thailand haven't been studied, says Takacs. "So we absolutely have no idea what kind of venoms or toxins we are eating away."