Cocaine-laden sharks raise alarm in Brazilian waters

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 bought 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. It is possible that the source of cocaine in the water is also 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 "very important and potentially concerning."

These discoveries indicate a potential health risk to humans, as sharks are commonly consumed in the state of Rio de Janeiro, throughout Brazil, and even worldwide – scientists add.

Last year, the media reported strange behavior of sharks near the Florida Keys archipelago. They were described by American environmental engineer Tracy Fanara and British marine biologist Tom Hird. 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 behavior of a hammerhead shark, which approached divers, even though it usually avoids contact with humans.

As "The Guardian" points out, scientists began to suspect that the unusual behavior of the sharks might be influenced by drugs. This cannot be ruled out as Florida is on a drug trafficking route. Scientists then decided to conduct an experiment, which involved throwing identical packages meant to imitate drug packages into the water. There was no shortage of sharks that tore the packages apart.

When we were filming in the Florida Keys, bales of cocaine were washed ashore twice in just one week, so it is truly a common problem — said Fanara in an interview with "The Guardian" journalists.