Off the coast of Brazil, scientists have for the first time detected cocaine residues in sharks. Thirteen Brazilian sharpnose sharks (Rhizoprionodon lalandii), caught near Rio de Janeiro, were examined. The analyses revealed alarmingly high concentrations of the drug in the muscles and livers of the animals, sometimes up to 100 times higher than ever measured before in other marine creatures.
How Does Cocaine Enter the Sea?
The research, conducted by the renowned Oswaldo Cruz Foundation, suggests that cocaine enters the oceans through various routes. On the one hand, through illegal laboratories where the drug is produced, and on the other, through human excretions after consumption. Less likely, but not ruled out, is the possibility that smugglers throw or lose cocaine packages into the sea.
“The findings are very important and potentially concerning,” explained Sara Novais, a marine ecotoxicologist at the University of Leiria, to the journal Science.
Unknown Consequences for Sharks and Their Offspring
Notably, all the female sharks examined were pregnant. The impact of cocaine on the unborn young is still completely unclear. Researchers point out that substances like cocaine could have similar effects on animals as they do on humans, which could have far-reaching consequences for shark populations.
The scientists emphasise that further studies are urgently needed to understand possible behavioural changes in the sharks as well as long-term damage to the marine ecosystem. Previous investigations in other regions had already shown that chemical residues from drugs in the sea are not uncommon. For example, last year traces of benzoylecgonine, a cocaine metabolite, were found in seawater off the UK’s south coast.
The discovery off Rio highlights how much illegal drug trafficking affects not only societies but also nature and its sensitive ecosystems.
