Study Reveals Cocaine Pollution Alters Salmon Behavior

A new study has revealed that cocaine pollution in waterways is altering the behavior of wild Atlantic salmon, causing them to swim farther and more recklessly than usual. Researchers from the Swedish University of Agricultural Sciences, Griffith University, the Zoological Society of London, and the Max Planck Institute of Animal Behavior conducted the first field experiment demonstrating these effects in a natural habitat, tracking 105 juvenile salmon in Sweden's Lake Vättern over eight weeks.

The team divided the hatchery-reared fish into three groups of 35: one exposed to cocaine via slow-release implants, another to benzoylecgonine, the drug's primary metabolite often found in higher concentrations in wastewater, and a control group with inert implants. All fish were fitted with electronic tracking tags and released into the lake. Initially, all groups explored widely, but differences emerged as the study progressed. Control fish gradually settled, ranging about 20 kilometers from the release site. Those exposed to cocaine traveled slightly farther, but the benzoylecgonine group showed the most pronounced changes, swimming up to 1.9 times farther each week and dispersing...