Annual testing of marble trout from zone of hybridization

Just like last year, we performed genetic testing of fish from the zone of hybridization. This year we have received fin clips from 33 individually tagged trout from 2 locations: the River Tolminka, tributary of the River Soča and from the River Soča just below the town of Kobarid. These samples were checked for non native genetic characteristic on 5 nuclear genetic markers (each genetic marker in 2 copies, one allele inherited from each parent) and on 1 mitochondrial genetic marker (in 1 copy, inherited from the mother only). Out of 33 samples, 8 show signs of hybridization with non native trout, 1 sample (sample 20) will not be used because of low quality of DNA isolate. Eggs and sperm will be taken from 24 trout with no detectable brown trout genetic characteristics, fertilised and raised in the hatchery and released back in the zone of hybridization.

Below is a simplified table of genotypes. These genotypes are not publishable, since the initial sampling was biased, only marble trout (by general appearance) were sampled, so the actual percentage of non native alleles in sampled locations might differ from our results (6.6%).

Table of genotypes across 1 mitochondrial and 5 nuclear markers. Samples with non native (=brown trout alleles) are marked red and will not be used in restoration program. f - female, m - male, M - marble trout specific allele, B - brown trout specific allele.