Scientists have discovered traces of cocaine in wild sharks off the coast of Brazil, highlighting the environmental risks posed by the illegal cocaine trade. The Brazilian sharpnose sharks were captured by fishing fleets near the state of Rio de Janeiro in southeastern Brazil between September 2021 and August 2023.
The study, published in the journal Science of the Total Environment, tested 13 sharks—three male and 10 female—all of which were found to have cocaine in their muscle tissue and livers. The drug, along with benzoylecgonine, the major metabolite of cocaine, was detected in these sharks, marking the first time cocaine has been identified in wild sharks globally.
Researchers are uncertain about the exact route of exposure but suspect that cocaine traces were likely discharged into coastal waters through raw sewage in rivers and urban canals. Another potential source could be cocaine packs drifting in water, which may pose a risk if sharks bite into them.
This phenomenon is not unprecedented. Another apex predator, infamously known as Cocaine Bear, a 500-pound black bear in Georgia, overdosed on cocaine believed to have been discarded by a drug smuggler. The bear’s remains were discovered in 1985 by narcotics investigators, and the story inspired a 2023 horror movie where the bear went berserk. In reality, authorities believe the bear overdosed swiftly.
The findings indicate significant ecological impacts of illicit drugs in marine environments. Researchers are particularly concerned about the potential reentry of cocaine into the food chain since these sharks are fished for their meat.
Illegal drugs and legal medications accumulating in waters are a global issue. In São Paulo state, cocaine contamination poses an ecological threat to marine life, including mussels and oysters. The level of cocaine in waters around São Paulo is reportedly similar to the amount of caffeine in coffee and tea, which researchers describe as a “huge concentration.” Cocaine has also been detected in the state’s drinking water.
In 2019, British researchers found freshwater shrimp were exposed to cocaine and other pharmaceuticals in the country’s rivers, further highlighting the widespread issue of drug contamination in aquatic environments. Global cocaine consumption has soared in recent decades, with Brazilians being among the biggest consumers in South America.
The Brazilian researchers selected the sharpnose shark for their study due to its small size and its habitat in areas significantly contaminated by sewage, making it an “environmental sentinel.” They found that cocaine levels were three times higher in the muscle than in the liver, with female sharks showing higher concentrations in muscle tissue compared to males. The detected levels of cocaine and benzoylecgonine in these sharks exceeded those reported for fish and other aquatic organisms by up to two orders of magnitude.
These alarming findings emphasize the urgent need for measures to address the environmental impacts of the illegal drug trade on marine life and broader ecosystems.
