IMIS - Marine Research Groups

Anadromous fish such as Sea trout (Salmo trutta) hatch in freshwater and leave their natal river as young fish (smolt) to migrate to sea, where they will spend months to years foraging to attain a larger size, and thus higher fecundity (Jonsson & Jonsson 2003). In late autumn/early winter, during the breeding season, they return to their natal rivers to spawn (Thorstad et al. 2016). Some individuals die after spawning, but most survive and migrate seaward to repeat the cycle (Jonsson & Jonsson 2002, Bendall et al. 2005). Those survivors are termed kelt (Bendall et al. 2005, Östergren & Rivinoja 2008). Most of our knowledge on sea trout migrations towards the sea is in systems with fjords (Finstad et al. 2005, del Villar-Guerra et al. 2014, Kristensen et al. 2019). Very little is known about the smolt and the kelt that migrate from rivers that flow directly into the sea, thus our understanding of the threats they may face in these systems remains poor. This project will investigate the behaviour and threats that brown trout face in such systems using telemetry. Acoustic receivers (THELMA BIOTEL) will be deployed in the river Hevring to detected brown trouts tagged with acoustic telemetry tags (THELMA BIOTEL)