People are taking so much cocaine that it’s spilling out into the ocean and dosing up sharks.
Scientists tested 13 of the predators caught in Brazilian waters, and they all had high levels of the drug in their muscles and livers – sometimes as much as 100 times as much as ever previously found.
They are exposed to cocaine through pollution, although the exact mechanism is not known.
It could be via waste water, with sewage containing urine and faeces from humans who consumed it flowing into the ocean.
Researchers writing in Science of the Total Environment said that another likely possibility was drainage from illegal labs processing the drug.
It was less likely that these sharks were directly nibbling on bales of coke lost or dumped in the sea, because these are not as commonly found in Brazil as they are near Mexico or Florida.
In the study “Cocaine Shark”: First report on cocaine and benzoylecgonine detection in sharks, researchers measured cocaine and its main metabolite benzoylecgonine in the bodies of 13 Brazilian sharpnose sharks caught in the wild on small fishing vessels.
They were chosen because they spend their lives in coastal waters and were most likely to be affected by pollution.
The problem of ‘cocaine sharks’ has gained attention in recent years, and has even been the subject of a Discovery TV programme looking at how they chomp on bales of the drug dumped by smugglers.
A 2023 horror film was renamed ‘Cocaine Shark’ after the success of ‘Cocaine Bear’, though it was not well received by viewers with one reviewing it as ‘the worst thing I have ever seen’.
The real-life cocaine sharks are likely to be negatively affected by their unintentional drug consumption, researchers said.
High levels could harm their eyesight, making it harder for them to hunt.
One way cocaine may damage sharks’ health is by affecting their eyesight, affecting their capacity to hunt.
Ecotoxicity expert Dr Tracy Fanara, from the University of Florida, told The Telegraph: ‘You might start to see lower fecundity and growth rates.’
It is possible that the cocaine could also affect their behaviour, making them more aggressive or even sparking feeding frenzies, though more research is needed.
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