Hunter-Gatherers Stocked Norwegian Lake With Trout 7000 Years Ago

Archaeologists dated wooden fish traps at Lake Tesse in Norway to around 4950 BC, establishing that hunter-gatherers transported brown trout into the isolated mountain lake at least 7000 years ago. The finding marks the oldest documented case of human-mediated fish translocation, according to Axel Mjærum at the University of Oslo. Lake Tesse sits at about 850 metres elevation.

It remained under the Fennoscandian ice sheet until roughly 8400 years ago. Once the ice retreated, the lake held no fish until people carried brown trout upstream. Large waterfalls prevented natural migration, and most Norwegian mountain lakes contained only this species.

The traps came to light in 2022 when hydropower operations lowered the lake level. Radiocarbon dating placed the oldest structure near 4950 BC. Tree-ring analysis fixed two later posts to the spring of 2669 BC and the winter of 2657-2656 BC.

Mjærum said the structures were maintained from approximately 5000 BC to 2650 BC. Before the lake was converted to hydropower storage in the 1940s, it produced nine tonnes of brown trout each year. Mjærum noted that a reliable food supply would have allowed entire family groups to remain in the mountains through part of the summer rather than limiting stays to small hunting parties.

2026.10392, places the Norwegian traps after eel-catching channels built in Australia 8600 years ago but centuries before farming began in Scandinavia.