Author(s): Morten Stickler; Eva C. Enders; Curtis J. Pennell; David Cote; David A. Scruton; Knut Alfredsen
Linked Author(s): Morten Stickler, Eva Enders, Knut Alfredsen
Keywords: Tlantic salmon (Salmo salar); Physical habitat; Movement; River ice; Gradient
Abstract: Though there has been an increased focus on the interaction between the physical habitat and the behaviour of Atlantic salmon parr (JAS; Salmo salar L. ), only a few studies have attempted to link winter conditions using hydraulic variables and ice conditions with behaviour and habitat use in natural flow environments. In this study, mobility of Atlantic salmon parr was studied during a freeze up event in late January in a small, natural river located in north-east Newfoundland, Canada. Two river sections with different gradients were selected as study reaches. The low gradient section (LGS) had a bed slope of 0.3 % and the high gradient section (HGS) had a bed slope of 1.8 %. Passive Interactive Transponder (PIT) technology was used to collect data on movement of 71 parr by using both fixed antennae and mobile tracking devices. Meteorological and physical conditions were continuously monitored. In the LGS, formation of surface ice dominated, giving stable conditions. In the HGS, formation of anchor ice and anchor ice dams occurred periodically leading to a dynamic environment. Parr inhabiting LGS moved significantly more than parr in HGS indicating a higher activity. In both sections the parr did not tend to explicit exploit ice edges, nor day or night. However, parr in HGS inhabited locations closer to the edge compared to parr in LGS. The obtained results imply different behavioral strategies within the fish population in relation to local, physical winter habitat conditions. Furthermore, the results underline the importance of considering the physical habitat when monitoring fish behavior and movement in lotic environments.
Year: 2006