Hunter-gatherers in Norway transported brown trout to an isolated mountain lake at least 7000 years ago to secure a reliable food source during summer trips. The finding represents the oldest known case of humans moving fish between bodies of water.
Researchers led by Axel Mjærum at the University of Oslo reached this conclusion after studying wooden fish traps uncovered at Lake Tesse when water levels dropped. The lake sits at about 850 metres elevation and was covered by ice until roughly 8400 years ago.
Radiocarbon dating placed the oldest trap around 4950 BC, with later posts felled in 2669 BC and 2657 BC. The structures show ongoing maintenance, indicating sustained fishing activity from around 5000 BC to 2650 BC.
The team ruled out natural fish dispersal due to waterfalls blocking upstream migration. Transport likely involved waterskins, allowing extended family stays in the mountains for hunting and fishing.
Earlier evidence of managed fishing exists elsewhere, including eel traps built in Australia about 8600 years ago.