It’s not a B movie: scientists say sharks are ingesting cocaine in drug-tainted water

Transcript

ARI SHAPIRO, HOST:

Now, a very serious story about cocaine in sharks. I mean it. Scientists in Brazil have evidence that sharks are being exposed to cocaine, and - shocker - it is not good for them. Here's reporter John Otis.

JOHN OTIS, BYLINE: Scientists at Brazil's Oswaldo Cruz Foundation dissected 13 wild sharpnose sharks caught near Rio de Janeiro. Rachel Davis, a biologist who worked on the study, told NPR that all 13 tested positive for cocaine in their muscles and livers.

RACHEL DAVIS: The key findings of the study are the presence of cocaine in sharks. The actual high levels of cocaine detected in muscle is indicative of chronic exposure.

OTIS: Narco traffickers being chased on the high seas often toss bales of cocaine overboard. But Davis says it's more likely the sharks in the study were exposed to Rio de Janeiro wastewater contaminated with the drug.

DAVIS: The main source would be human use of cocaine and metabolization and urine and feces discharge. And the second source would be from illegal refining labs.

OTIS: Davis points out that cocaine impacts the brain and could lead to hyperactive behavior among sharks, though she says the issue needs more research. The findings in Brazil add to a growing body of research on marine wildlife and cocaine. For example, a 2018 study in the U.K. found that eels exposed to cocaine were having trouble mating.

TRACY FANARA: Exposure to recreational drugs can actually slow down their processes to the point where they miss migration periods that are essential for the survival of their species.

OTIS: That's Tracy Fanara, an environmental engineer at the University of Florida. She took part in a documentary last year called "Cocaine Sharks" in which scuba divers tried to determine whether sharks were being exposed to the drug.

(SOUNDBITE OF DOCUMENTARY, "COCAINE SHARKS")

UNIDENTIFIED PERSON: Whoa, hammerhead. Hammerhead right there.

OTIS: Cocaine isn't the biggest problem sharks face, but Fanara says the documentary was an excuse to remind people that all kinds of human pollution is wreaking havoc on ocean life.

FANARA: You know, this could be really catastrophic, but cocaine does a good job of getting people's attention.

OTIS: For NPR News, I'm John Otis. Transcript provided by NPR, Copyright NPR.