Overview
- Researchers in Sweden ran a peer‑reviewed field test that tracked 105 hatchery‑raised Atlantic salmon in Lake Vättern for eight weeks.
- Juvenile fish exposed to cocaine‑related chemicals grew more active over time and traveled farther than unexposed controls.
- The cocaine breakdown product benzoylecgonine caused the largest shift, with some fish moving nearly twice as far each week and being detected up to 12.3 km from release.
- Exposure levels matched concentrations measured near sewage outlets, and scientists note standard treatment often fails to remove benzoylecgonine.
- Researchers said long‑term ecological effects remain unclear and urged closer monitoring, noting separate work has found drug traces in other marine species such as Bahamian sharks.