A new study reports that sharks in the Bahamas have tested positive for consuming cocaine, caffeine and other substances.
According to the findings, published in the journal Environmental Pollution, pharmaceuticals such as acetaminophen and sertraline, as well as caffeine, cocaine and other chemicals were present in the systems of three shark species.
Known as CEC, or contaminants of emerging concern, these substances were found to be particularly prevalent in tourist areas.
Of the 85 sharks analyzed in the study, Caribbean reef sharks, Atlantic nurse sharks and lemon sharks were found to have varying levels of the painkillers diclofenac and acetaminophen in their bodies, as well as cocaine and caffeine.
A Caribbean reef shark.
Photo by Lawson Wood / SplashdownDirect / Rex Features
Stimulants such as cocaine and caffeine are linked to hyperglycemia, which can interfere with the sharks’ capacity to manage blood sugar and can also disrupt the ability to metabolize fats.
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Research also found that sharks that had consumed CECs “showed altered triglycerides, urea, and lactate levels,” which may cause “physiological responses” in species that test positive for contaminants.
The study is the first to detect caffeine and acetaminophen in any shark species worldwide.
Five species of sharks were captured for research purposes, including lemon, Atlantic nurse, blacktip, Caribbean reef and tiger sharks.
This is not the first time cocaine has been detected in sharks — more than 10 sharks off the coast of Brazil tested positive for cocaine in 2024 — but it is the “first report concerning CECs and potentially associated physiological responses in sharks from The Bahamas,” the study says. It also notes that the archipelago is often referred to as “pristine,” meaning it is considered an unspoiled environment with a thriving, well-preserved ecosystem.
In 2011, the country established the Bahamas Shark Sanctuary, protecting its entire ocean territory by banning commercial shark fishing and trade in shark products.
Aerial shot of Paradise Island in the Bahamas. A 10-year-old boy was airlifted to the U.S. after being bitten by a shark at a resort in Paradise Island.
Laurie Chamberlain/Getty Images
The study attributed its findings in part to tourism, which it says is a “major economic driver” that, when coupled with an increase in the number of vacation homes and rental properties, “significantly heightens the volume and chemical complexity of local wastewater.”
Many sharks inhabit shallow coastal areas where tourism traffic is high, which increases their exposure risk, the study added.
This has been a year of firsts for shark-related discoveries.
In Febraury, researchers released footage of a sleeper shark, captured in January 2025, traversing a barren Antarctic seabed, a finding that contradicted a widely held belief that the deep-sea dwellers don’t live in the region.
The shark was large, estimated at between three and four metres long, and was spotted swimming at a depth of 490 metres in temperatures hovering just above 1 degree Celsius.
Data on sharks’ travel patterns and ranges in the region are relatively scarce due to its remoteness, experts said. And while climate change could be a contributing factor in the shark’s sighting, it’s also possible that slow-moving sleeper sharks were already in Antarctica and nobody ever noticed.
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