'Cocaine sharks' found in the Atlantic - and 'drug use' may be changing their behaviour
23 July 2024, 14:49
Sharks have tested positive for cocaine off the coast of Brazil, scientists claim - and it could be affecting their behaviour.
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Marine biologists found high levels of cocaine in the livers and muscles of 13 sharpnose sharks swimming in the sea near Rio de Janeiro.
The concentrations were nearly 100 times higher than levels previously found in fish.
Scientists believe that the cocaine is probably making its way into the water via illegal labs or through the excrement of drug users.
It could also be getting into sharks' systems after being dumped or lost at sea by drug traffickers, researchers claim - although this is a less probable explanation.
Scientists have not worked out if the cocaine is changing sharks' behaviour - but it is a possibility, they have said.
"Cocaine targets the brain, and hyperactive and erratic behaviour has been noted in other animals", said Dr Enrico Mendes Saggioro, an ecotoxicologist from the Oswaldo Cruz Institute.
"It’s a possibility and further studies are required."
But consuming the drug could be having other effects on the health of sharks - including life expectancy and fertility.
"You might start to see lower fecundity and growth rates", according to Dr Tracy Fanara, an expert in ecotoxicology and environmental engineering from the University of Florida.
"They may not be going nuts from the cocaine but it could reduce their life expectancy," she told the Telegraph.
She added: "This is representative of problems all over the world, whether it involves cocaine or fertiliser or herbicides.
"We are releasing these chemicals into the environment and the question is, how are we affecting the ecosystem?"
