Sharks tested positive for cocaine off the coast of Brazil: Why does it matter?

A recent study published in the journal Science of the Total Environment confirmed that sharks off the coast of Brazil were found with traces of cocaine in their systems.

The study, titled “‘Cocaine Shark’: First report on cocaine and benzoylecgonine detection in sharks,” covered the details of the positive drug tests in Brazilian sharpnose sharks.

While scientists are still “teasing out the implications of this finding,” per the Smithsonian Magazine , experts are becoming concerned with the environmental effect of illegal human drug use.

The affected sharks

Thirteen Brazilian sharpnose sharks were tested off the coast of Rio de Janeiro, according to CNN . The species was chosen for its small size and coastal habitat.

Cocaine was found in the liver tissue of all of the sharks, with three times as much found in the muscle tissue of each shark. Additionally, female sharks had “higher cocaine concentrations in muscle tissue compared to males.”

“We were actually dumbfounded,” Rachel Ann Hauser Davis, a biologist and co-author of the study, told The New York Times . “We were excited in a bad way, but it’s a novel report. It’s the first time this data has ever been found for any top predator.”

The animals indicated a chronic exposure to cocaine. According to the BBC , the concentrations of the drug were as many as 100 times the amount found in other aquatic animals.

Scientists speculate that cocaine is finding its way into the water through illegal labs or through drug users’ excrement. There is also a possibility that packs of the drug are being be lost or tossed by traffickers at sea.

Dr. Hauser Davis shared with The New York Times that wastewater treatment plants can’t filter substances like cocaine very effectively, dumping them into the ocean instead.

A future threat?

Scientists are not totally sure what the side effects may be for sharks and other marine wildlife that have ingested cocaine.

In a joint statement, co-authors of the study Mendes Saggioro and Rachel Ann Hauser Davis said that previous research shows the harm that can be done to fish and mussels by the drug.

“It is probable, although not yet proven that exposure would have deleterious physiological effects on the sharks,” they said, per CNN .

According to NPR , a study done in 2018 found that cocaine-exposed eels had trouble mating. Environmental engineer Tracy Fanara told NPR about the potential other potential effects and sharks and marine wildlife.

“Exposure to recreational drugs can slow down their processes to the point where they miss migration periods that are essential for the survival of their species,” she said.

Fanara, who also led a research team for a documentary called “Cocaine Sharks,” told The New York Times that cocaine is only a small part of a bigger problem.

“Cocaine gets people interested,” she said. “But we have antibiotics, antidepressants, pharmaceuticals, sunscreen, insecticides, fertilizers. All of these chemicals are entering our ecosystem.”