Anàlisi genètica de la truita comuna, Salmo trutta L., a la conca alta de la Noguera Ribagorçana

Abstract

The population structure of brown trout in the upper Noguera Ribagorçana, including areas within the «Aigüestortes i Estany de Sant Maurici» National Park, was assessed by electrophoretic variation at 50 protein coding loci. An important genetic differentiation was detected among samples, basically due to the different genetic impact of the released exogenous hatchery fish. The occurrence of fish of hatchery ancestry is lower in the fished and heavily stocked areas outside the National Park. Apparently, the capture of hatchery fish prior to sexual maturity permits the perpetuation of a predominantly native population in this area. The occurrence of fish of hatchery origin is higher within the National Park, where almost complete displacement of native fish has occurred at Barranc de Morrano. This population represents the main risk for the conservation of the genetic diversity of the specie and the ecosystem. These data suggest important errors in the management undertaken in both fished and protected areas.