Hunter-gatherers introduced fish to a mountain lake 7000 years ago

Hunter-gatherers in Norway transported brown trout into isolated mountain lakes at least 7000 years ago, as evidenced by ancient fish traps found in Lake Tesse. The lakes, previously covered by an ice sheet, could not have been naturally populated due to geographical barriers like waterfalls. Radiocarbon dating of traps places their construction around 4950 BC, with ongoing maintenance until 2650 BC.