Capacité de la méthode des microhabitats à prédire l'habitat de reproduction de la truite commune

Abstract

The Instream Flow Incrémental Method was applied to brown trout reproduction, in 205 morphodynamic units of 6 Pyrénées mountain streams. The corrélation between Weighted Usable Area (WUA) and redd density was higher when using a local habitat suitability curve, instead of the standard cun/e of BOVEE (1978). However, WUA was high in some units with low redd density. This was due to an over-estimation of the WUA in some types of unit where the gravel taken into account in WUA calculation was scattered between coarse material and thus unusable for trout spawning. This study underlines the importance of using an aggregation criterion when describing the substratum for spawning salmonids.