Genetic diversity of domestic brown trout stocks in Europe

Berrebi, Patrick; Horváth, Ákos; Splendiani, Andrea; Palm, Stefan; Bernaś, Rafał

doi:10.1016/j.aquaculture.2021.737043

Cited by 16 publications

(11 citation statements)

References 83 publications

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“…To counterbalance brown trout population declines, Mediterranean river basins were extensively restocked during the 20th and at the beginning of the 21st centuries, using non-indigenous hatchery stocks from North Atlantic basins [ 36 , 44 , 98 , 99 ]. All of these stocks share a homogeneous genetic background [ 29 , 36 ]. The genetic impact of restocking in Mediterranean countries is frequently evaluated using the nuclear diagnostic marker LDH-C *.…”

Section: Discussionmentioning

confidence: 99%

“…However, restocking can endanger native populations by disrupting local adaptations due to the introduction of maladapted specimens (e.g., [ 32 , 34 , 35 ]). Most of the hatchery brown trout used for restocking derived from a Central European stock pertaining to the Atlantic lineage, genetically differentiated from native fish [ 29 , 36 ]. The introgression by restocking practices were evaluated using different molecular markers, such as allozymes or microsatellites.…”

Section: Introductionmentioning

confidence: 99%

“…Although restocking practices with allochthonous stocks have mostly been discarded [ 36 , 39 , 44 , 45 ] and replaced by other strategies such as supportive breeding [ 36 ], it is necessary to develop more sophisticated and cost-effective tools to assess the introgression of natural populations as a result of restocking with the following purposes: (1) to implement recovery measures in accordance with the degree of introgression (e.g., increasing fishing quotas over highly impacted populations or eradicating naturalized populations of hatchery origin); (2) to avoid the use of breeders from introgressed populations in supportive breeding programs or to find local stocks; and (3) to identify introgressed populations acting as black spots contributing to the spread of foreign genetic variants.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Genomic Hatchery Introgression in Brown Trout (Salmo trutta L.): Development of a Diagnostic SNP Panel for Monitoring the Impacted Mediterranean Rivers

Casanova

Heras

Abràs

et al. 2022

Genes

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Brown trout (Salmo trutta L.) populations have been restocked during recent decades to satisfy angling demand and counterbalance the decline of wild populations. Millions of fertile brown trout individuals were released into Mediterranean and Atlantic rivers from hatcheries with homogeneous central European stocks. Consequently, many native gene pools have become endangered by introgressive hybridization with those hatchery stocks. Different genetic tools have been used to identify and evaluate the degree of introgression starting from pure native and restocking reference populations (e.g., LDH-C* locus, microsatellites). However, due to the high genetic structuring of brown trout, the definition of the "native pool" is hard to achieve. Additionally, although the LDH-C* locus is useful for determining the introgression degree at the population level, its consistency at individual level is far from being accurate, especially after several generations were since releases. Accordingly, the development of a more powerful and cost-effective tool is essential for an appropriate monitoring to recover brown-trout-native gene pools. Here, we used the 2b restriction site-associated DNA sequencing (2b-RADseq) and Stacks 2 with a reference genome to identify single-nucleotide polymorphisms (SNPs) diagnostic for hatchery-native fish discrimination in the Atlantic and Mediterranean drainages of the Iberian Peninsula. A final set of 20 SNPs was validated in a MassARRAY® System genotyping by contrasting data with the whole SNP dataset using samples with different degree of introgression from those previously recorded. Heterogeneous introgression impact was confirmed among and within river basins, and was the highest in the Mediterranean Slope. The SNP tool reported here should be assessed in a broader sample scenario in Southern Europe considering its potential for monitoring recovery plans.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Genomic Hatchery Introgression in Brown Trout (Salmo trutta L.): Development of a Diagnostic SNP Panel for Monitoring the Impacted Mediterranean Rivers

Casanova

Heras

Abràs

et al. 2022

Genes

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“…This can be difficult to differentiate from natural multiple colonisations except where the lineage involved is unlikely to have colonised naturally. Thus, Atlantic lineage (sensu Bernatchez, 2001) Eurasian trout have been introduced outside their native range into many waters that contain native trout of other major lineages (Berrebi et al, 2021).…”

Section: Evolution Of Salmonid Sympatric Populationsmentioning

confidence: 99%

Identifying and conserving sympatric diversity in trout of the genus Salmo, with particular reference to Lough Melvin, Ireland

Ferguson

Prodöhl

2022

Ecology of Freshwater Fish

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Salmonid (Salmonidae) sympatric diversity is the co-occurrence, in a lake or river, of two or more reproductively isolated populations/subpopulations, or phenotypes resulting from phenotypic plasticity. Sympatric populations can arise through allopatric and/ or sympatric evolution. Subsequently, allopatric lineages can occur in sympatry due to independent colonisation and/or through anthropogenic introduction. Sympatric divergence is often driven by feeding opportunities, with populations segregating as planktivorous, benthivorous and piscivorous ecotypes ("trophic polymorphism"), and further segregation occurring by feeding depth and body size. Subpopulations evolve by natal homing where a water has two or more discrete spawning areas, often resulting in phenotypically and ecologically cryptic sympatry. Most known sympatric populations/phenotypes in trout of the genus Salmo (Eurasian trout aka brown trout) involve sympatric piscivorous (ferox) and lifetime invertivorous trout. Segregation on the benthic-limnetic axis has been poorly studied in Eurasian trout compared with other salmonids but is likely commoner than currently described. While three sympatric populations/species of Eurasian trout are recognised from Lake Ohrid (Albania/ North Macedonia), limited ecological information is available and there are only two lakes with three or four sympatric populations with described benthic, limnetic and piscivorous trophic segregation: Lough Melvin (Ireland) and Loch Laidon (Scotland), the latter having the only identified case of a sympatric profundal benthic feeding populations, possibly due to the absence of Arctic charr (Salvelinus alpinus) in the lake.Many thousands of waters are yet to be examined. Some sympatric populations are extinct, and others are vulnerable with conservation action being urgently required. This should ideally be based on populations/conservation units, but the lack of recognition of intraspecific units in most legislations in the native Eurasian trout range necessitates a pragmatic approach, with species classification, where appropriate, based on integrative taxonomy. Some sympatric populations clearly merit species status and should be formally classified as such if a valid previous name is not available.

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“…Resident brown trout populations inhabit parts of Polish river catchments, mainly in northern and southern Poland, which is generally consistent with the historical range of the migratory form before river-sea connectivity was destroyed by human activity. All river populations are considered to be admixed with domestic strains after more than 40 years of stocking 3 with several domestic lineages 4 .…”

Section: Introductionmentioning

confidence: 99%

Evidence of unidirectional gene flow in a fragmented population of Salmo trutta L.

Bernaś

Wąs‐Barcz

Árnyasi

et al. 2021

Sci Rep

Self Cite

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Selection, genetic drift, and gene flow affect genetic variation within populations and genetic differences among populations. Both drift and selection tend to decrease variation within populations and increase differences among populations, whereas gene flow increases variation within populations but leads to populations being related. In brown trout (Salmo trutta L.), the most important factor in population fragmentation is disrupted river-segment connectivity. The main goal of the study was to use genetic analysis to estimate the level of gene flow among resident and migratory brown trout in potential hybridization areas located downstream of impassable barriers in one river basin in the southern Baltic Sea region. First, spawning redds were counted in the upper river basin downstream of impassable barriers. Next, samples were collected from juveniles in spawning areas located downstream of barriers and from adults downstream and upstream of barriers. Subsequently, genetic analysis was performed using a panel of 13 microsatellite loci and the Salmo trutta 5 K SNP microarray. The genetic differentiation estimated between the resident form sampled upstream of the barriers and the anadromous specimens downstream of the barriers was high and significant. Analysis revealed that gene flow occurred between the two forms in the hybridization zone investigated and that isolated resident specimens shared spawning grounds with sea trout downstream of the barriers. The brown trout population from the river system investigated was slightly, internally diversified in the area accessible to migration. Simultaneously, the isolated part of the population was very different from that in the rest of the basin. The spawning areas of the anadromous form located downstream of the barriers were in a hybridization zone and gene flow was confirmed to be unidirectional. Although they constituted a small percentage, the genotypes typical upstream of the barriers were admixed downstream of them. The lack of genotypes noted upstream of the barriers among adult anadromous individuals might indicate that migrants of upstream origin and hybrids preferred residency.

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Genetic diversity of domestic brown trout stocks in Europe

Cited by 16 publications

References 83 publications

Genomic Hatchery Introgression in Brown Trout (Salmo trutta L.): Development of a Diagnostic SNP Panel for Monitoring the Impacted Mediterranean Rivers

Genomic Hatchery Introgression in Brown Trout (Salmo trutta L.): Development of a Diagnostic SNP Panel for Monitoring the Impacted Mediterranean Rivers

Identifying and conserving sympatric diversity in trout of the genus Salmo, with particular reference to Lough Melvin, Ireland

Evidence of unidirectional gene flow in a fragmented population of Salmo trutta L.

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