A first-of-its-kind discovery.
Remember Cocaine Bear? Well, we might have a sequel on our hands: Nearly 40 years after a 175-pound black bear died of a cocaine overdose and went on to inspire a hit movie, sharks off the coast of Brazil tested posted for the illicit substance.
In findings published last week, researchers who analyzed 13 Brazilian sharp-nosed sharks found evidence of cocaine and benzoylecgonine — a metabolite produced when cocaine is broken down in the body — in all of them. In fact, the concentrations were as much as 100 times higher than in other aquatic life that may swim in drug-contaminated waters, suggesting chronic exposure.
So far, it’s unclear whether cocaine damages the sharks’ health or prompts the kind of mind-altering behavior that is present in human users. As scientists call for more research, here’s why marine experts say these findings are a small part of a much larger problem.
Behind the study
The Brazil study, which was published in the journal Science of The Total Environment, was prompted after researchers discovered high levels of cocaine in the rivers that form Rio de Janeiro’s drainage basin or watershed.
Among researchers’ more notable findings, cocaine levels were around three times higher in muscle tissue than in liver tissue, and female sharks had higher cocaine concentrations in muscle tissue compared to males. But they don’t cite an explanation for why this was the case, and further research is likely needed.
Other marine biologists have also looked into the presence of this substance in these aquatic creatures. For instance, the 2023 documentary Cocaine Sharks explored whether sharks were devouring cocaine from dumped packages off the coast of Mexico. However, in the end, their findings were inconclusive.
That means the Brazil report is the first proof that scientists have of the animals being exposed to the substance in the wild. Researchers now worry about cocaine reentering the food chain, as the sharks are often fished for their meat. “We were actually dumbfounded,” biologist Rachel Ann Hauser Davis, who worked on the study, told The New York Times. “It’s the first time this data has ever been found for any top predator.”
Wait, how did sharks ingest cocaine in the first place?
Researchers don’t know exactly how the sharks were exposed to the drug, but they have two main theories. The first is that packages from illegal cocaine labs could be lost or dumped into the ocean by drug traffickers. But researchers don’t believe that’s the primary cause in this case. “We don’t usually see many bales of coke dumped or lost at sea [in Brazil], unlike what is reported in Mexico and Florida,” study co-author Enrico Mendes Saggio told CNN.
So what could it be instead? The researchers believe cocaine is “probably discharged in raw sewage in the rivers and urban canals that flow into the coastal study region.” And it’s no coincidence that the study was conducted off the coast of Brazil: The authors note that the country has the second-largest market for the drug in South America, a region where about 22 percent of cocaine users live (that amounts to about 4.8 million people).
This cocaine contamination is also affecting all water, including the kind we drink. According to The New York Times, most wastewater treatment plants around the world can’t effectively filter this substance, and it has been detected in Brazil’s drinking water at levels similar to the amount of caffeine in coffee and tea.
And yet, cocaine isn’t the biggest problem sharks face.
Though these top predators have endured a lot over the course of their 450 million years on Earth, the study’s authors note that 31.2 percent of shark species are facing extinction. This is only exacerbated by other threats, such as the commercial fishing industry, which frequently targets sharp-nosed sharks for their meat or bait. Like many other shark species, they’re also accidentally caught by shrimp fisheries.
As for the cocaine, it’s just one of the many dangerous substances floating around in our seas and waterways. All kinds of human pollutants, including antibiotics, antidepressants, and fertilizers, wreak havoc on ocean life.
Yet pharmaceutical waste — whether it comes from legal or illegal drugs — is a woefully understudied issue for wildlife in oceans, rivers, and lakes. Researchers note that only a tiny fraction (6.9 percent) of shark species are at risk of becoming extinct because of pollution as a contributing factor. Still, they believe more studies are needed to accurately measure the impact of pollution on sharks’ ability to thrive because it could have a broader impact on other marine life.
“Sharks and rays play crucial roles in marine ecosystems as predators, shaping marine trophic chains, and are recognized as sentinel species for environmental contamination,” Hauser Davis writes in the study. “Additionally, they represent a valuable protein source and are extensively consumed worldwide.”
With this latest report, researchers hope the findings will prompt additional research on testing the drug on other animals, including sea turtles.
