Author(s): Antoni Palau; Rafel Rocaspana; Enric Aparicio; Jorge Alcazar
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Abstract: The construction of fish-pass in dams and weirs is an environmental measure of recognized importance in the case of migratory species. The brown trout (Salmo trutta) has often been considered a species that makes important longitudinal movements along the rivers, especially during the breeding period, thus justifying the need to build fish-pass. In the present study it has been found that trout populations in Pyrenean rivers (NE Spain) are very sedentary and that only a small fraction of specimens (< 6%) show a certain mobile behavior, although it cannot be considered migration. It has been proven that the differential behavior between sedentary and mobile trout specimens may have a genetic basis. The role of these more mobile specimens within the population is unknown. They may have a function linked to the conservation of the gene pool of the species, but because of their greater mobility, it seems that they can play an important role as repopulation of stretches of river affected by major natural (floods, avalanches, .. .) or human (pollution, .. .) disturbances. The results obtained indicate that the trout fish-pass do not always seem to be necessary for the conservation of the species.
Year: 2018