Estudi de l’edat, el creixement i la demografia de l’espècie invasora Phoxinus sp. en tres estanys dels Pirineus

Abstract

The common minnow (Phoxinus sp.) is a specie in the family of Cyprinidae that lives in fresh, cold and oxygenated waters. Currently, it is distributed through all Europe, East Asia and Central Asia. This study focuses on the location of the species in the ponds of the Pyrenees, which was introduced at the end of the 20th century as live bait for trout fishing. This has caused an important negative impact, altering the nutrient cycle, transforming the trophic network and causing a diminution and / or elimination of native species. The LIFE + LimnoPirineus project in 2014 was involved with the aim of improving the state of conservation of aquatic species and habitats of these ponds in the Pyrenees of European interest. This study aims to characterize Phoxinus sp. populations which are in three ponds of the Pyrenees; Naorte, Tres Estanys and Bassa Nord de Dellui. In order to carry it out, the growth patterns will be analysed using the Von Bertalanffy model and the demographics, based on the instantaneous mortality rate, for each of the three populations. These analyses will be carried out thanks to calcified bone structures, which are named otoliths. These structures allow to analyse the age of the fish thanks to growth rings, like the trunks of the trees. If there is a bad reading of these rings, later errors will appear in the characterizations of the populations, for this reason, this study also tries to make an improvement of the methodology used until the moment to realize the otoliths reading. The results of this study have concluded that the reading with the new methodology of the otoliths of Phoxinus sp. has been a great progress for the characterization of the populations of the ponds, which have presented high longevity and slow growth rates. Regarding mortality, it has been seen that it is similarly slow in the three ponds, in line with the high longevities presented