Spawning microhabitat selection by brown trout in the Linthkanal, a Mid-Sized River

摘要

The Linthkanal, a medium sized artificial river canal (mean discharge 55 m~3 s~-1), does not fit the usual concept of a spawning water for brown trout. Nevertheless, during the spawning seasons of 1995/1996 and 1996/1997 100-150 redds were observed. Microhabitat parameters such as depth, current velocity, bottom substrate composition, and proportion of fine sediment at both spawning and random sites had been measured. At the spawning sites mean values for current velocity were 56 cm s~-1 and for depth 159 cm. These values are notably higher than those recorded in other studies. Microhabitat preferences for spawning sites were analyzed using multivariate logistic regression. The result was significant, indicating that the microhabitat parameters at chosen spawning sites were different from other areas in the canal. To elucidate these differences further, suitability and electivity indices were calculated.