Some Swedish scientists decided to drug salmon with cocaine and then release them. It happened just what was expected
There is more than just fish and algae in the world’s rivers. More or less diluted amounts of chemicalsincluding pesticides, pharmaceuticals and illegal drugs. He checked it a few years ago a team from King’s College that, after taking samples in various parts of the county of Suffolk, in England, found cocaine and ketamine residues. Researchers have long known that wildlife is exposed to these compounds, but one question remained: How do drugs affect them in their natural environment? To find out in Sweden have drugged to dozens of salmon. Drugging salmon? That’s how it is. It sounds strange, but it is exactly what a group of scientists from Griffith University, the Zoological Society of London and the Max Planck Institute, among other organizations, have done. They basically took 105 salmon (salmo salar) from a fish farm, they divided them into several groups and added implants that supplied them with drugs. Then they released them. More or less as in the famous case of Cocaine Bearbut in a planned way. How did they do it? 35 of those salmon were implanted with a special device that slowly released coca into their bodies. A similar system was incorporated into others, although modified to provide benzoylecgoninethe main metabolite of cocaine. The third group did not receive any substance to act as a control. Once prepared, the salmon, all young specimens, were released into Lake Vätternsouth of Sweden. For eight weeks the researchers dedicated themselves to finding out how each group behaved. The specimens in the experiment wore a special tracking device, so (with the help of sensors installed around the lake) scientists could follow their trail and calculate how far they swam. And what did they find out? That the drugged salmon behaved very differently from the ‘sober’ ones. Especially those who received benzoylecgonine. After releasing the fish on the southwest bank of the Vättern, the researchers found that the salmon exposed to coca swam on average five more kilometers than the ‘clean’ ones, a considerable difference that falls short, however, when the specimens to which the metabolite was supplied are analyzed. They swam almost 14 km more, which led them to enter the northern area of the lake. “The team found that fish exposed to benzoylecgonine swam up to 1.9 times farther per week than those not exposed and dispersed up to 12.3 km farther,” duck Griffith University. The agency also clarifies that the changes “became more evident” as the days passed, which shows that exposure to coca alters the behavior of fauna. Why is it important? Let the drugged salmon swim more kilometers and cover more space than others without ‘doping’ is more important than it may seem. These behavioral changes influence aspects such as what places the fish occupy, where they feed or the risks they face. More kilometers also translates into greater physical effort, which forces the salmon to look for more sources of nutrition to recover energy. “Where fish go determines what they eat, what eats them, and how populations are structured,” comment Dr. Marcus Michelangeli. “If pollution is driving these patterns, it has the potential to affect ecosystems in ways we are only beginning to understand.” But that was already known, right? Yes. And no. We knew that aquatic fauna is exposed to the drugs that we consume. The 2019 study in Suffolk and others, such as the made in 2016 in Puget (Washington), during which researchers detected traces of Prozac, Lipitor and cocaine in the body of salomes. We also knew that these substances alter the behavior of wildlife. In fact, scientists they already checked how water fleas exposed to coca swim faster or crabs are more reckless. The really interesting thing about the study carried out in Sweden is that it has allowed us to go one step further: to leave the laboratories, which were the isolated space in which these types of experiments had been carried out until now, and carry out research in natural environments and the same conditions that fauna is found. It hasn’t been easy. Although the team guarantees that the entire experiment has been done in safe conditions for the ecosystem and humans. Obtain all necessary permits, they confess researchers, it was “a tedious process.” And what to do now? Dr. Jack Brand, from the Swedish University of Agricultural Sciences, recognize that more studies are needed to fully understand the consequences of pollution in rivers, lakes and seas. It is an important issue, among other reasons because the substance that has most altered salmon is benzoylecgonine, which has a special impact. “It was the metabolite, which we know is found in higher concentrations in nature, that had a much more profound effect on the behavior and movement of the fish,” warns in statements to Guardian. “This suggests that if we perform evaluations without including compounds such as these metabolites and their derivatives, we could be overlooking an important part of the environmental risks to which we expose these animals.” Images | Colin Davis (Unsplash), Katmai National Park and Preserve (Flickr) and Scazon (Flickr) In Xataka | In 2001, a yacht took refuge on a remote island in the Atlantic. Days later its inhabitants breaded fish with coca