Overview
- Researchers tracking juvenile Atlantic salmon in Sweden’s Lake Vättern found that fish exposed to benzoylecgonine, the main cocaine byproduct, swam more and spread out farther than unexposed fish.
- The peer-reviewed experiment followed 105 hatchery-raised salmon for eight weeks using acoustic tags and slow-release implants to compare cocaine, its metabolite, and a control.
- The metabolite produced stronger and more consistent changes than cocaine itself, which showed weaker effects on movement.
- Scientists and independent toxicologists say the extra swimming could drain energy, change foraging, and raise predation risk, though effects on survival and reproduction remain unknown.
- Because many treatment plants do not fully remove drug metabolites that people excrete, experts urge broader monitoring and wastewater upgrades as similar residues have been found in other species.