A Benchmark for Atlantic Salmon Conservation: Genetic Diversity and Structure in a Southern European Glacial Refuge before the Climate Changed

Atlantic salmon Salmo salar supports highly valuable commercial and recreational fisheries in Europe, but its stocks are currently overexploited and threatened by climate change. Its southernmost populations (in northern Spain) play a key role in conserving the species’ original genetic diversity, w...

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Bibliographic Details
Published in:Fishes
Main Authors: Ana Almodóvar, Graciela G. Nicola, Daniel Ayllón, Sheila Leal, Daniel F. Marchán, Benigno Elvira
Format: Article in Journal/Newspaper
Language:English
Published: MDPI AG 2023
Subjects:
climate change
conservation genetics
effective population size
stocking
genetic variability
introgression
Biology (General)
QH301-705.5
Genetics
QH426-470
Atlantic salmon
Salmo salar
Online Access:https://doi.org/10.3390/fishes8060321
https://doaj.org/article/57e2c4ae573449b181206767ab2163dc
Description
Summary:Atlantic salmon Salmo salar supports highly valuable commercial and recreational fisheries in Europe, but its stocks are currently overexploited and threatened by climate change. Its southernmost populations (in northern Spain) play a key role in conserving the species’ original genetic diversity, which is endangered due to decades-long (1970s to 1990s) massive stocking with non-native stocks. Their decline is well documented, but the effect of stock transfer and conservation efforts is unclear. Nine microsatellite loci were amplified from archival samples (scales from 1958–1959) from eight Spanish rivers to analyse the species’ natural genetic dynamics before its decline started. Allelic richness was high in the historical populations (the 1950s) and above most contemporary estimates. Private alleles were found in most rivers, indicating high local uniqueness and relative isolation among river basins. Some alleles are regional markers since they are rare or absent from contemporary northern European populations. Effective population size suggested good conservation status, with higher values than those estimated for contemporary populations. Strong population structure and genetic differentiation between rivers were found, with limited gene flow, restricted to geographically close populations. Our estimates of historical genetic diversity and structure from southernmost salmon populations are a powerful benchmark to guide conservation programs.

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