Creixement i demografia de les poblacions de l’espècie Salmo trutta introduïdes en diversos estanys d’alta muntanya dels Pirineus

Abstract

Salmo trutta is one of the most studied species in Europe, however, the populations that live in the lakes of the Pyrenees are little known. The most outstanding fact of this lack of knowledge is the ignorance that these fish populations are not native of these habitats and, therefore, they are one of the major causes of the decline of biodiversity of these ecosystems. LIFE + LIMNOPIRINEUS, that began the summer of 2014 and that is going to run for five years, it has the objective of improving the conservation status of species and aquatic habitats in the high mountains of the Pyrenees. The removal of this non-native species is one of the actions to achieve this improving and with the sampled individuals from the lakes it has been possible to do the next research that have the aim to realize a characterization of the populations of Salmo trutta present in the high mountain lakes of the Pyrenees. This characterization is done by the measurements of the furcal length and the determination of the ages of each individual by the otoliths reading, which allow to describe the growth and the survival of the populations present in these habitats by the adjusting of the models Von Bertalanffy and constant survival, respectively. Moreover, has been done an analysis of the body pigmentation pattern of each trout for knowing its linage. The ages obtained by the otoliths readings show unstructured populations with a poor density of young individuals. The parameters obtained by the growth corves indicated moderate asymptotic lengths compared with others freshwater ecosystems and little differences between the growth rates. On the other hand, the mortality rates, obtained by the adjustment of the survival constant model, are quite similar between the different lakes. Nevertheless, these little differences can be related with the lakes characteristics like the depth, the surface or the presence of the specie Phoxinus sp. Finally, the analysis of the body pigmentation pattern shows two different patterns: lakes with dominance of Mediterranean lineage or lakes with a strong presence of Atlantic lineage