The rehabilitation of the Marble trout, Salmo marmoratus in the upper Soca River basin, Slovenia

Abstract

1° Colloque Italo-slovène sur la truite marmorataInternational audienceFollowing repeated restocking of Brown trout (Salmo trutta) dating from 1906, the marble trout (Salmo marmoratus) seems to have disappeared as a result of genetic pollution (hyhridization) from the lower reaches of the' Soca River.in Slovenia. A project for rehabilitating the Marble trout has been undertaken. A priliminary exploratory stage (1993-1995) that resulted in the publication in 1996 of an Action Plan, written in English and Slovenian, suggested that the cause of the disappearance of the Marble trout was hybridization, established the validity of the project in the region in question and provided us with essential information (occurence of genetically pure populations) that could be used to define our future strategy. We chose genetic rehabilitation, i.e. the replacement of a population of introduced and introgressed fish by a population of genetically pure fish of the native species, rather than a programme of eradicating undesirable fish by chemical methods, which would have been incompatible with the region's context. Our overall strategy therefore had two main aims: to ensure the long-term survival of populations of pure Marble trout (species conservation) and to rehabilitate the genes of Marble trout in the hybridization zone until foreign genes have almost been eliminated. Undergoing studies of the phase two of the project are described and preliminary results are presented