Cocaine-laced sharks: Alarming discovery off Rio de Janeiro coast

Scientists examined 13 sharks off the coast of Brazil and found high concentrations of cocaine in each of them. The concentration was 100 percent higher than previously reported in marine creatures. How did drugs end up in these predators?

Marine biologists examined 13 Brazilian sandbar sharks caught off the coast of Rio de Janeiro. Scientists from the Oswaldo Cruz Institute in Brazil purchased the sharks from small fishing boats that caught these and other species and then conducted tests on them. According to the BBC, all samples tested positive, and the concentration of cocaine was even 100 times higher than previously reported in other aquatic species.

Scientists point out that the drug enters the water primarily from illegal laboratories, where cocaine is produced, as well as from the excrement of people using this drug. The source of cocaine in the water may also be packages thrown by smugglers.

Sara Novais, a marine ecotoxicologist at the Center for Marine and Environmental Sciences at the Polytechnic Institute of Leiria, told the journal "Science" that the discoveries are significant and potentially concerning.

These findings are indicative of potential human health risks, as sharks are highly consumed in the state of Rio de Janeiro, in fact, throughout the entire Brazilian territory and indeed, worldwide – scientists add.

Last year, the media reported the strange behaviour of sharks near the Florida Keys archipelago. American environmental engineer Tracy Fanara and British marine biologist Tom Hird described them. Their concern was raised by a sand shark swimming in circles as if trying to catch something researchers couldn't see. Equally disturbing was the behaviour of a hammerhead shark, which approached divers, although it usually avoids contact with humans.

As "The Guardian" points out, scientists began to suspect that drugs might influence the unusual behaviour of the sharks. This cannot be ruled out as Florida is on the drug trafficking route. Scientists then decided to conduct an experiment involving throwing identical packages meant to imitate drug packages into the water. No shortage of sharks tore the packages apart.