Angling impact on conservation of Spanish stream-dwelling brown trout Salmo trutta

Spanish brown trout, Salmo trutta L., populations are currently overexploited as a result of unsuitable management activities, and their genetic uniqueness is threatened by introgression of foreign genes because of stocking. In this study, the status and management of trout fisheries were reviewed and the effects of fishery management on abundance, production and life history of trout in Spain assessed. Angling exploitation has reduced the mean age, the age diversity and number of trout exceeding the minimum size in exploited sections. Likewise, exploited areas show a general decrease in overall abundance parameters and production, as well as a depletion of the breeding stock and population fecundity. Current minimum size limit control reduces the spawning chances in fast-growing populations because of higher susceptibility to angling harvest. The effects of fishery management on population dynamics, production and life-history characteristics exhibit different patterns among Spanish rivers, and seem to depend on the environmental and biological characteristics of the populations. The current declining trend of brown trout could be reduced by river-specific management and alternative fishing regulations.