Archaeological evidence suggests humans transported brown trout to an isolated mountain lake in Norway thousands of years before farming began in the region.
Key facts
- •Lake Tesse was covered by the Fennoscandian ice sheet until roughly 8,400 years ago.
- •Natural fish migration into the lake was prevented by geographical features such as large waterfalls.
- •The oldest fish traps found at the site date to approximately 4950 BC.
- •Before being used for hydropower in the 1940s, the lake produced 9 tonnes of brown trout annually.
- •Evidence of earlier fish farming exists elsewhere, such as eel traps in Australia dating back 8,600 years.
Hunter-gatherers introduced brown trout to Lake Tesse in Norway at least 7,000 years ago to secure a food source for summer foraging trips. Axel Mjærum of the University of Oslo states this is the oldest documented instance of human-mediated fish translocation globally. The lake, located at an elevation of 850 meters, was previously covered by the Fennoscandian ice sheet until approximately 8,400 years ago, making natural fish migration impossible due to geographical barriers like waterfalls.
By the numbers
Evidence from ancient fish traps
Researchers discovered elaborate fish traps in 2022 after water levels in Lake Tesse were lowered. Radiocarbon dating of the wooden remains indicates the oldest traps date back to around 4950 BC. By analyzing tree ring chronologies, the team confirmed that younger posts were felled between 2669 BC and 2656 BC, suggesting the traps were maintained and utilized for thousands of years.
Environmental management before farming
The introduction of fish to the lake represents an early form of environmental management, occurring centuries before the arrival of agriculture in Scandinavia. While the specific method of transport remains unknown, researchers suggest hunters may have used waterskins to carry the fish. This reliable food supply likely allowed entire family groups to stay in the mountains for longer periods during the summer.
Timeline
- 8400 years agoThe Fennoscandian ice sheet retreated from the Lake Tesse area.
- 4950 BCThe oldest identified fish traps were constructed.
- 2657-2656 BCAnother wooden trap post was felled, 12 years after the previous one.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by New Scientist.
