Estatus de les poblacions de truita comuna al Pirineu

Abstract

Since the past century, the brown trout populations (Salmo trutta) of the Catalan Prynne's rivers have suffered from large restocking of trouts, with the aim of maintaining or improving the natural river's populations and to favor the sport fishing activity, with hatchery-reared non-native fish from Central Europe. These are genetically different from the native Mediterranean populations, where both groups represent the two groups represent divergent evolutionary lineages. Such measure have become a serious threat to the conservation of the native genetic diversity due to genetic introgression processes. In order to change this situation, improve the genetic state and to prevent futures hybridizations, brown trout genetic refuges were created in several sections of the rivers of the different basins. Between the period of 2014 - 2016, the Autonomous Catalan Government restarted the monitoring of the genetic estate of the wild populations of S. trutta, previously done between 1993 until 2006, in order to actualize the information about their genetic state. Two genetic markers were used, a group of 5 microsatellites and the locus LDH-C1*, as to evaluate the average genetic introgression degree for each section of the rivers sampled. In the present project we created a data base (with a total of 73 samples) with the genetic information collected during this 2014 - 2016 period in the basins of the Ter, Llobregat, Segre, Noguera Pallaresa i Noguera Ribagorçana, and was determined for every sampled point if it was included or not in a genetic refugee at the moment of the extraction. After the analysis of the such data, we found the existence of significant differences for the genetic introgression degree between the different Catalan Pyrenees basins. But differences on the mean introgression degree between analyzed river stretches inside and outside of the genetic refuges were not found. The expansion and creation of new genetic reserves will be essential for an improvement in the conservation of the native genetics populations. We propose the extension of the genetic reserve of N. Pallaresa to include all the sites analyzed in this project and the extension of the genetic reserve of the Segre basin for the Oden River, due to its exceptional low level of introgression