Sharks are getting high on cocaine due to drug-contaminated water in Brazil

Sharks off the coast of Brazil have been found with traces of cocaine, and scientists are concerned about the drug’s potential effects on their behavior.

While a drug-fueled great white shark might sound like the stuff of fiction, the reality is both troubling and alarming for marine life.

Cocaine seeps into the ocean through various means, including insufficient sewage treatment and discarded drug packets, leading to unexpected consequences for aquatic species.

Cocaine contamination and its discovery

Recent research reveals that cocaine has infiltrated marine ecosystems globally, with traces found in sewage and surface waters across 37 countries between 2011 and 2017. The drug has been detected in a range of aquatic organisms such as mollusks, crustaceans, and bony fish.

However, this is the first study to investigate its presence in sharks. The findings highlight a troubling level of contamination.

Brazilian researchers analyzed 13 Brazilian sharpnose sharks (Rhizoprionodon lalandii) off Rio de Janeiro’s coast for this study. These small sharks, under three feet in length, primarily feed on small fish and squid.

The researchers dissected the sharks and analyzed samples from their muscles and livers.

The results were alarming. Every shark tested positive for cocaine, and 12 out of 13 had benzoylecgonine—a byproduct of cocaine metabolism—present in their systems.

Dr. Rachel Ann Hauser-Davis, a British scientist from the Oswaldo Cruz Foundation and a member of the research team, explained that this high level of cocaine contamination is likely due to human activities.

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

The study points to illicit drug manufacturing as a key source of cocaine entering the ocean . The researchers also explored the possibility of sharks consuming cocaine discarded by smugglers but deemed this less likely.

The primary concern is chronic exposure to the drug, which could have severe health impacts on these sharks.

Potential effects on shark health and behavior

The impact of cocaine on sharks could be significant. Cocaine exposure may impair their vision, alter their hunting abilities, and potentially reduce their lifespan.

The study found that the cocaine levels in these sharks were 100 times higher than those previously detected in other aquatic creatures. Chronic exposure to such high levels of cocaine could damage their DNA, affect their metabolism, and lead to behavioral changes.

While the idea of “cocaine-fueled” sharks making headlines may seem sensational, the real concern is the drug’s effect on their health and survival. The researchers emphasized that these findings could have broader implications for ecosystems and human health. As sharks are consumed widely in Rio de Janeiro and other parts of Brazil, there could be potential risks to humans as well.

As reported by The Telegraph , Dr. Tracy Fanara, an ecotoxicologist and environmental engineering expert from the University of Florida, commented on the study’s implications, “They may not be going nuts from the cocaine but it could reduce their life expectancy.”

This raises worries about how drug pollution could indirectly affect human health through the food chain.

Broader context and related findings

The research aligns with earlier warnings from marine biologists about drug-addled sharks. In July 2023, concerns were raised about sharks in Florida potentially being exposed to cocaine dumped by smugglers.

During Discovery’s Shark Week, marine expert Tom Hird and his team observed unusual behavior among sharks and noted that when a fake cocaine package was dropped into the water, the sharks rushed to bite it.

These findings highlight the urgent need to tackle drug pollution in oceans and its effects on wildlife.

The study shows how human activities are affecting marine ecosystems, stressing the importance of better waste management and environmental protections to keep both sea life and people healthy.

The research was published last week in the journal Science of the Total Environment .