Scientists find Brazilian sharks on cocaine

No, Cocaine Shark is not a sequel to the recent Cocaine Bear movie (based on a true story). It is, however, a real thing.

Researchers from the Oswaldo Cruz Foundation recently detected cocaine in Brazilian sharpnose sharks living off the coast of Rio de Janeiro. This marks the first instance of the drug being found in free-ranging sharks, raising concerns about the impact of human activities on marine ecosystems.

Cocaine and sharks

The study tested 13 Brazilian sharpnose sharks and discovered cocaine in both the liver and muscle tissue of all specimens. According to the research published in the journal Science of the Total Environment, cocaine levels were approximately three times higher in muscle tissue than in liver tissue. Additionally, female sharks exhibited higher concentrations in their muscle tissue compared to males.

Enrico Mendes Saggioro, co-author of the study and an ecotoxicologist at the foundation, said the finding is primarily due to sewage discharge contaminated by general drug use and by illegal drug production laboratories.

“We don’t usually see many bales of coke dumped or lost at sea here, unlike what is reported in Mexico and Florida,” Saggioro said.

The study highlights the growing issue of cocaine pollution in coastal waters, exacerbated by increased drug consumption and inadequate sewage treatment infrastructure. Brazil, the second-largest consumer market for cocaine in South America, faces significant environmental challenges due to these factors.

The results showed “chronic exposure due to human use of cocaine in Rio de Janeiro and the discharge of human urine and feces by sewage outfalls, as well as from illegal labs,” said Rachel Ann Hauser-Davis, a member of the research team from the foundation.

Potential ecological impact

The potential health effects of cocaine on sharks are still unknown. Previous research has shown that cocaine can harm other aquatic species, such as fish and mussels, leading researchers to believe it could also have detrimental physiological effects on sharks.

The study also raises concerns about the broader ecological impact, suggesting that other marine creatures, including the prey of these sharks, may also be contaminated with cocaine. This contamination can potentially enter the human food chain, as sharks are routinely consumed in Brazil and many other countries.

One expert not involved in the study cautioned that although little current data indicated the drug was driving the sharks into crazed frenzies, it could have long-term effects on their health. The University of Florida’s Tracy Fanara, an ecotoxicology and environmental engineering specialist, suggested that it might affect the sharks’ growth and breeding rates.

“They may not be going nuts from the cocaine but it could reduce their life expectancy,” she told The Telegraph. “This is representative of problems all over the world, whether it involves cocaine or fertilizer or herbicides. We are releasing these chemicals into the environment and the question is, how are we affecting the ecosystem?”

Addressing a growing concern

Fanara took part in the Discovery Channel film Cocaine Sharks, which explored whether sharks in the Gulf of Mexico were feeding on cocaine packages dumped by traffickers.

The research team plans to extend their studies to other species of sharks and rays, particularly those living in river estuaries, to assess the extent of cocaine contamination in various marine environments. They also aim to investigate migratory fish, such as mullet, to determine if migratory behavior influences cocaine accumulation.

This study is part of a broader context of drug contamination in aquatic environments. In 2021, researchers found that brown trout can become addicted to methamphetamine in contaminated waterways. Similarly, studies have reported traces of illicit drugs, pharmaceuticals, and pesticides in freshwater shrimp in the UK and oxycodone in mussels in Puget Sound, USA.

To address this emerging environmental issue, the researchers recommend enhanced monitoring through regular surveillance programs to assess the extent of cocaine and other drug contamination in marine environments. Improving sewage treatment infrastructure to prevent drug discharge into coastal waters is also important.