Sharks off Brazilian coast found with cocaine, raising behavior concerns
Marine biologists have discovered alarming levels of cocaine in sharks off the coast of Brazil, sparking concerns that the drug may be altering their behavior. A recent study involving 13 Brazilian sharpnose sharks from waters near Rio de Janeiro revealed high concentrations of cocaine in their muscles and livers.
Sources of cocaine exposure
While the exact source of the cocaine remains unclear, scientists have several theories. It is believed that the drug could have entered the ocean through the drainage of illegal drug labs or from the excrement of drug users via untreated sewage. Another possibility is that the sharks fed on bundles of cocaine lost or dumped in the sea by drug smugglers. However, a scientist told The Telegraph, “We don’t usually see many bales of coke dumped or lost at sea here, unlike in Mexico and Florida,” suggesting it is highly unlikely the sharks ingested cocaine from dumped packages.
Chronic exposure and potential effects
The test results indicated “chronic exposure” to cocaine in the sharks. While scientists estimate the drug is harmful to them, the extent of its impact on their behavior remains uncertain. Dr. Enrico Mendes Saggioro, an ecotoxicologist, noted, “This may be the case, as cocaine targets the brain, and hyperactive and erratic behavior has been noted in other animals. It’s a possibility and further studies are required.”
Researchers collected the small sharks near Rio de Janeiro, dissected them, and tested their organs. They found cocaine concentrations up to 100 times higher than previously recorded in other marine animals. Every sample tested positive for cocaine, with 92 percent of muscle samples and 23 percent of liver samples also testing positive for benzoylecgonine, one of cocaine’s main metabolites. This marks the first evidence of cocaine being identified in free-ranging sharks.
Unknown long-term effects
The long-term effects of cocaine on these sharks are still unknown. Scientists suspect that the drug could damage their eyesight, impairing their hunting abilities. While the cocaine may not cause the sharks to exhibit extreme behaviors, it could potentially reduce their life expectancy. A scientist mentioned, “They may not be going nuts from the cocaine, but it could reduce their life expectancy.”
This discovery underscores the need for further studies to understand the full impact of cocaine on marine life and the broader ecosystem. The presence of such high levels of cocaine in sharks highlights the far-reaching consequences of human activities on wildlife and the environment.
