Brazilian Sharks Test Positive for Cocaine

Cocaine Shark is already a horrible looking B-movie, but it’s also a reality as trace amounts of the drug have been detected in sharks near Brazil.

While a rampaging cokehead great white would undoubtedly make for an excellent antagonist, the reality is slightly less exciting and far more alarming in the grand scheme of things. Cocaine makes its way into the ocean through several avenues, including release from inadequate sewage treatment facilities and stray packets dropped into the water by smugglers that then get bitten open by wildlife (the latter scenario sounding rather familiar).

Due to these processes, traces of cocaine have been detected in sewage and surface waters in at least 37 countries between 2011 and 2017. The drug has also infiltrated various forms of aquatic life, including mollusks, crustaceans, and bony fish. But with all that said, no studies had ever looked into whether sharks are affected.

In a paper published last week in the journal Science of the Total Environment, Brazilian researchers sought to rectify that by capturing 13 Brazilian sharpnose sharks off the coast of Rio de Janeiro. The species is relatively small, measuring under three feet (0.9 meters) in length, and it feeds mostly on small fish and squid.

After capturing the sharks, the scientists dissected them to get samples of their muscles and livers, which were then analyzed for signs of cocaine and related chemicals. The results were shocking: Every single shark tested positive for cocaine, while 12 of the 13 had benzoylecgonine—a chemical produced when cocaine is filtered through the liver—in their systems.

While the study focused exclusively on Brazilian sharpnose sharks, the researchers didn’t rule out the possibility that other species could also be exposed to water-borne narcotics. They noted that many shark species are facing serious decline due to overfishing. Being exposed to cocaine could result in severe damage to shark health, including harming their DNA, affecting their ability to metabolize fats, or causing behavioral changes.

“Considering the psychotropic effects of drugs of abuse on vertebrates, behavioural changes may occur, which, although sub-lethal, could impact the species’ survival in ways that remain unexplored,” the researchers wrote. 

While Jaws on drugs might seem like a nightmare scenario, the possible effects on humans of cocaine being ingested by the carnivorous fish is slightly more subtle. 

“These findings are indicative of potential human health risks, as sharks are highly consumed in the state of Rio de Janeiro, in fact, throughout the entire Brazilian territory and indeed, worldwide,” they wrote.