Bahamas sharks test positive for cocaine and caffeine

Eighty-five sharks sampled in the Bahamas carried traces of common pharmaceuticals and stimulants including caffeine and cocaine, according to a study published in the journal Environmental Pollution. Researchers detected chemicals such as acetaminophen and the antidepressant sertraline in Caribbean reef sharks, Atlantic nurse sharks and lemon sharks, with some of the highest signals reported in heavily visited coastal areas.

The findings add to a growing literature on “contaminants of emerging concern” turning up in marine predators, often in places marketed as pristine. The Bahamas has banned commercial shark fishing and trade in shark products through the Bahamas Shark Sanctuary, yet the study’s authors argue that protection from fishing does not shield animals from chemical exposure when wastewater inputs rise alongside coastal development.

According to Global News’ summary of the paper, the researchers link the pattern to tourism-driven pressure on local sewage systems: more visitors, more short-term rentals and more vacation homes increase both the volume and the chemical mix of wastewater. Sharks spend time in shallow coastal waters where outfalls and nearshore contamination are most likely to accumulate, making them a practical sentinel species for what is entering the broader food web.

The study also reports associations between contaminant exposure and changes in blood chemistry. Stimulants such as caffeine and cocaine are tied to hyperglycaemia in other animals, and the authors say sharks that had consumed these chemicals showed altered triglycerides, urea and lactate levels—markers that can reflect stress and disrupted energy metabolism. The paper does not claim behavioural intoxication in the pop-culture sense; it documents measurable residues and physiological correlations that warrant follow-up.

Cocaine in sharks is not unprecedented: researchers off Brazil reported cocaine residues in more than 10 sharks in 2024. What is new here, the authors say, is the combination of compounds and the location. The Bahamas study is described as the first to detect caffeine and acetaminophen in any shark species worldwide, and the first to report these contaminants alongside potential physiological responses in Bahamian sharks.

The chemicals detected are not exotic: painkillers, antidepressants and stimulants are widely used on land, incompletely removed by many wastewater systems, and persistent enough to be measured in marine organisms. The study’s implication is that the limiting factor is not whether a place has wildlife protections on paper, but whether it has the infrastructure to keep human effluent from becoming part of the ocean’s baseline chemistry.

The Bahamas’ shark sanctuary was created to stop fishing boats, not to filter wastewater. The sharks are still swimming through whatever comes out of the pipes.