Good news for conservation: mitochondrial and microsatellite DNA data detect limited genetic signatures of inter-basin fish transfer inThymallus thymallus(Salmonidae) from the Upper Drava River

Abstract

Key-words:European grayling, Thymallus thymallus, genetic introgression, Drava/Drau River, stocking In the last few decades, numerous populations of European grayling, Thymallus thymallus, have been suffering from stocking-induced genetic admixture of foreign strains into wild populations. Concordantly, genetic introgression was also reported for grayling stocks inhabiting the Upper Drava River, but all published genetic data based on specimens caught at least a decade ago, when stocking load was strong. Here, we applied mitochondrial control region sequencing and nuclear microsatellite genotyping to Upper Drava grayling fry collections and reference samples to update patterns and extent of human-mediated introgression. In contrast to previous data, we highlighted an almost genetic integrity of Drava grayling, evidencing limited genetic signatures of trans-basin stocking for grayling of Northern Alpine Danubian origin. Recent hybridisation was detected only twice among sixty-nine samples, while several cases of later-generation hybrids were disclosed by linking mitochondrial sequence to nuclear genetic data. The observed past, but very limited recent genetic introgression in grayling from Upper Drava seems to reflect shifting stocking trends, changing from massive introduction of trans-basin fish to more conservation-oriented strategies during the last 27 years. In a conservation context, we encourage pursuing the use of local wild grayling for supportive-and captive-breeding, but underline the need for genetic approaches in brood-stock selection programs. Finally, our integrated results from sibship reconstruction validate our strictly fry-based sampling scheme, thus offering a reasonable alternative also for other rheophilic fish species with similar life-history characteristics. RÉSUMÉBonne nouvelle pour la conservation : les données de l'ADN mitochondrial et des microsatellites détectent des signatures génétiques limitées de transfert entre bassins du poisson Thymallus thymallus (Salmonidae) dans le cours supérieur de la rivière Drava Mots-clés :Ombre commun, Thymallus thymallus, Au cours des dernières décennies, de nombreuses populations d'ombre commun, Thymallus thymallus, ont souffert de mélange génétique induit par des alevinages dans les populations sauvages utilisant des souches étrangères. Une introgression génétique a également été signalée pour des stocks d'ombre de la rivière Drava amont, mais toutes ces données génétiques publiées sont basées sur des

Combining Harvest and Genetics to Estimate Reproduction in Wolves

“…The value of estimating counts of parents and family groups through sibship reconstruction has been demonstrated in other systems, such as monitoring abundance of social bee colonies by identifying sisters among foraging workers and estimating the number of female sea turtles (green [ Chelonia mydas ] and Kemp's ridley [ Lepidochelys kempii ] sea turtles) laying multiple clutches per season at the same nesting site (Toquenaga and Kokuvo ; Frey et al , ; Geib et al ). Fisheries and aquaculture systems have used similar methods to shed light on genetic variability between age stages, assess stocking strategies, and reconstruct putative parental genotypes among externally fertilized species (Liu and Ely , Li et al , Meraner et al , Hasanat et al ). These applications, like ours, expand the information gained through genetic monitoring approaches.…”

Defining conservation units in a stocking‐induced genetic melting pot: unraveling native and multiple exotic genetic imprints of recent and historical secondary contact inAdriatic grayling

“… The CR sequence dataset‐set ( N = 644) was achieved by merging haplotype information reported in Meraner and Gandolfi () (sample IDs: 1, 3, 5, 7–20, 24, 25, 29, 30; Table ) and Meraner et al. () (sample IDs: 21–23, 26, 27, 28; Table ). In addition, we obtained CR sequences of 139 specimens (sample IDs: 2, 4, 6; Table ) by adopting the methodology described in Meraner and Gandolfi (). The microsatellite dataset ( N = 683) consisted of a set of reference genotypes reported in Meraner et al.…”

“…In addition, we obtained CR sequences of 139 specimens (sample IDs: 2, 4, 6; Table ) by adopting the methodology described in Meraner and Gandolfi (). The microsatellite dataset ( N = 683) consisted of a set of reference genotypes reported in Meraner et al. () (IDs: 21–28; Table ) and newly genotyped grayling specimens (all remaining IDs; Table ). We assayed 15 microsatellite markers: six tetranucleotide markers, namely TAR100, TAR103, TAR104, TAR108, and TAR110 (Diggs and Ardren ) as well as BFRO013 (Koskinen and Primmer ) and nine dinucleotide markers, namely BFRO004 (Snoj et al.…”

Recreational Fisheries: The Need for Sustainability in Fisheries Management of Alpine Rivers

“…The most important precondition is to select or identify a donor population of suitable genetic origin. In Austria, decades of stocking fish of foreign origin and trans-basin spreading of populations of both brown trout and European grayling substantially altered the genetic integrity of wild fish populations, particularly those of salmonid species (Duftner et al 2005;Pinter 2008;Meraner et al 2013b;Schenekar et al 2014). Nowadays, fish species, predominantly cyprinids, e.g., nase (Chondrostoma nasus) and barbel (Barbus barbus), are stocked with increasing regularity and in increasing quantities.…”

“…Nowadays, different tagging methods for all size classes of fish are established. Even eyed eggs, e.g., of brown trout, can be marked using chemical dyes (e.g., Unfer and Pinter 2013), or their origin can be classified through molecular-biological methods (e.g., Meraner et al 2013b). It is surprising that the majority of fisheries managers spend huge amount of money for stocking but monitoring studies on the success are scarce and often judged as too expensive.…”