Sharks Tall sharks off Rio worry scientists Benjamin Ekroth
Published 13.48
The sharks off the coast of Brazil receive a "constant supply" of cocaine, according to a new study. Photo: Carlos Grillo/Getty Images
Brazilian sharks have been found to have high levels of cocaine in them.
According to researchers, they have ingested significantly more than a line, if you are a shark.
- The findings are very important and potentially worrying, says marine researcher Sara Novais to the magazine Science.
Quick version Brazilian researchers note that it is common for sharks off the coast of Rio de Janeiro to have high levels of cocaine in their system.
In a new study, the researchers examined thirteen whitetip sharks that all had cocaine in their livers and muscle tissues. According to the study, the level of cocaine was in some cases 100 times higher than what had previously been observed in marine animal species, writes the New York Times.
- We were completely dumbfounded, says Rachel Ann Hauser Davis, biologist and co-author of the study.
"Worrying"
The findings suggest that it is not a one-time occurrence and that the sharks would have accidentally ingested cocaine in some strange way. The researchers believe that it is probably due to a constant supply of cocaine in the water where sharks live.
- The findings are very important and potentially worrying, says marine researcher Sara Novais to the magazine Science. She has not worked on the new report but says further research is now needed. This is to determine if the level of cocaine is harmful to the sharks – or to people who eat them, as it is common to eat shark in Brazil.
Shark is common on the plate in Brazil, now we have to investigate whether the cocaine content is harmful to humans. Photo: Ricardoffj / Getty Images
It cannot be ruled out that it could be cocaine dumped in the water by smugglers because cocaine is water soluble. But the researchers' main hypothesis is that the cocaine ends up in the water via the sewage from illegal labs - and via unclean sewage from homes.
- We believe that the biggest source is excretion through urine and feces from people who use cocaine, says Rachel Ann Hauser Davis to the New York Times, who writes that most of today's treatment plants have difficulty filtering cocaine residues effectively.
Can be affected
Previous studies and observations indicate that aquatic animals are affected by drugs in the water. Last year there were reports from the coast of Florida where sharks were observed behaving strangely, they could, among other things, circle imaginary objects in the water. It was then suspected that the sharks had ingested cocaine that ended up in the water due to smuggling, skwrites Spiegel.
Cocaine on the rise in the Mediterranean. Photo: Italian Financial Police / AP
According to the British Guardian, scientists believe that the cocaine could interfere with the sharks' vision, which would make them worse hunters. Another concern is that cocaine may interfere with sharks' ability to reproduce, according to Science.
Can become addictive
There are also studies that have shown that fish can develop an addiction. A 2023 study from the University of Agriculture in Prague showed that trout ingesting methamphetamine, at the same concentrations found in water treated from sewage treatment plants, became addicted. They became less active and showed withdrawal symptoms, according to Spiegel.
But there are more serious things than drugs that can end up in the water.
- Cocaine makes people curious. But there are antibiotics, antidepressants, pharmaceuticals, sunscreen, insecticides and fertilizers – all chemicals that make their way into the ecosystem, says Tracy Fanara, an environmental scientist in Florida, to the New York Times.
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