Anadromous whitefish of the Torne

The project includes two complementary sections, which investigate the status of the migratory (anadromous) whitefish population in the Torne (Tonionjoki / Torne älv), their migration behaviour and their survival during the migration. The first section assesses whitefish samples that will provide important information on the body size, body condition, sex ratio and age distributions in the population. In addition, the novel data will be compared with previously collected data from in the 1980s, 1990s and early 2000s. In the second section, a network of acoustic receivers set into the river and around the river mouth will identify the movements and spawning areas of tagged whitefish individuals. Such acoustic telemetry tagging will produce valuable spatial and temporal data on the whitefish spawning migration.

Overall, the project will provide important information on the migratory whitefish population in Finland's largest free-flowing river discharging into the Baltic Sea. The information can be used to assess the population status, population structure, overall fishing pressure (especially via age distribution), changes compared to the previous decades, and the migratory behaviour of whitefish. The commercial fisheries importance of whitefish and their declining catches highlight the need for such research knowledge.