The River Teno salmon run monitoring

Salmon ascending to the Teno river are counted with sonars at Polmak, c. 55 km upstream from the river mouth. Sonar monitoring is started annually on late-May early-June after the highest spring flood has decreased. Monitoring continues until mid-September.

At the monitoring site in Polmak the river is c. 120 m wide and 1-6 m deep. Two sonar units are used, one in each shore. The river is slightly narrowed by using guiding fences which leaves c. 100 m to be monitored with sonars.

Daily salmon (fish) numbers are being updated to this page as fast as possible and at least on weekly basis. Weekends causes some delays in updating the fish numbers. All the fish numbers presented in here are preliminary numbers and they are prone for changes. The final numbers will be ready only after the season, in September-October.

During odd years (2019, 2021, 2023) considerable numbers of pink salmon ascend the Teno river nowadays. Pink salmon are c. 40-65 cm in length and their separation from small salmon is difficult during the monitoring season. There are also other species (e.g. sea trout) migrating past the monitoring site, which cannot be separated from salmon during the monitoring period.

The final estimate of the total salmon run is therefore only available after the monitoring period during Autumn when all different datasets have been analyzed


Daily numbers of ascending fish in 2022 and 2023


Cumulative numbers of ascending fish


Daily numbers of ascending fish in 2018-2021

The sonar counting of salmon (fish) ascending to the River Teno is conducted in the lower river at Polmak where the river is narrow and the flow velocity is low. There are tow sonar units, one on each shore. Short guiding fences ensures that fish are not migrating behind the sonar units. Photo: Mikko Kytökorpi.

Additional information:

Researcher Panu Orell, tel. 029 532 8757,

Research assistant Mikko Kytökorpi, tel. 029 532 2625,