Results
The estimated population density, assessed based on a standardised daily
mark-release procedure, was ca. 1 individual per 1 m section of the
river, which is an intermediate density for the species (Chaput-Bardy et
al., 2010; Kuitunen et al., 2010; Stettmer, 1996).
All behavioural traits related to courtship and boldness were
significantly repeatable. In contrast, among the traits connected to
aggression only “number of hits” was repeatable (Tab. 2).