Making sense of the relationships between Ne, Nb and Nc towards defining conservation thresholds in Atlantic salmon (Salmo salar)

Ferchaud, A-L.; Perrier, Charles; April, Julien; Hernández, Cecilia; Dionne, Mélanie; Bernatchez, Louis

doi:10.1038/hdy.2016.62

Cited by 52 publications

(66 citation statements)

References 79 publications

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“…There was no significant correlation between N b and N c across 10 years in the River Nivelle. Indeed, N b and N c did not co‐vary across years leading to high inter‐annual variation of N b : N c as previously reported for the species (Palstra et al, ; Ferchaud et al, ; Perrier et al, ). This typical variation in N b : N c in combination with lack of correlation between N b and N c may indicate that variance in reproductive success could be an important factor in N b variation in this population, in addition to the number of individuals that effectively reproduced (Luikart et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…In this context, genetic monitoring of effective population size has been recognized as a complementary resource for conservation planning (Dodson et al, ). Routine implementation in population management, however, has not followed, probably due to the continuous development of refined methods over the past decade (Wang et al, ) and the limited number of studies showcasing practical applications in the context of population management (but see Ozerov et al, ; Whiteley et al, ; Ferchaud et al, ; Perrier et al, for recent examples). A second objective of this study is to bridge the gap between academia and resource management practice.…”

Section: Introductionmentioning

confidence: 99%

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Estimating the effective number of breeders from single parr samples for conservation monitoring of wild populations of Atlantic salmon Salmo salar

Bacles

Bouchard

Lange

et al. 2018

Journal of Fish Biology

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This study assesses whether the effective number of breeders (N ) can be estimated using a time and cost-effective protocol using genetic sibship reconstruction from a single sample of young-of-the-year (YOY) for the purposes of Atlantic salmon Salmo salar population monitoring. N was estimated for 10 consecutive reproductive seasons for S. salar in the River Nivelle, a small population located at the rear-edge of the species distribution area in France, chronically under its conservation limit and subjected to anthropogenic and environmental changes. Subsampling of real and simulated data showed that accurate estimates of N can be obtained from YOY genotypes, collected at moderate random sampling intensity, achievable using routine juvenile electrofishing protocols. Spatial bias and time elapsed since spawning were found to affect estimates, which must be accounted for in sampling designs. N estimated in autumn for S. salar in the River Nivelle was low and variable across years from 23 (95% C.I. 14-41) to 75 (53-101) and was not statistically correlated with the estimated number of returning adults, but it was positively correlated with the estimated number of YOY at age 9 months. N was found to be lower for intermediate levels of redd aggregation, suggesting that the strength of the competition between males to access females affects reproductive success variance depending on redd spatial configuration. Thus, environmental factors such as habitat availability and quality for spawning and YOY development predominate over demographic ones (number of returning adults) in driving long-term population viability for S. salar in the River Nivelle. This study showcases N as an integrated parameter, encompassing demographic and ecological information about a reproductive event, relevant to the assessment of both short-term effects of management practices and long-term population conservation status.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Estimating the effective number of breeders from single parr samples for conservation monitoring of wild populations of Atlantic salmon Salmo salar

Bacles

Bouchard

Lange

et al. 2018

Journal of Fish Biology

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“…Heggenes et al., ; Østergaard et al., ), whereas others have failed to detect it (e.g. Ferchaud et al., ; Palstra & Ruzzante, ; Vähä et al., ). Some mutually non‐exclusive explanations may account for this discrepancy.…”

Section: Discussionmentioning

confidence: 99%

Short‐term temporal instability in fine‐scale genetic structure of masu salmon

2017

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Identifying spatial extent and temporal patterns of population genetic structure is important for understanding evolutionary relationships among local populations and for designing conservation programmes. However, little attention has been devoted to understand whether genetic structure is temporally stable or unstable, and how genetic characteristics may change over time. The goal of this study was to assess the temporal stability of the genetic structure of masu salmon (Oncorhynchus masou). To examine the temporal component of genetic variation in genetic structuring within a river system, we used 810 masu salmon collected from eight tributaries of the Atsuta River, Hokkaido, Japan, over three consecutive years (i.e. 2007–09). We assessed the temporal stability of the genetic structure in 15 microsatellite loci by comparing genetic diversity, effective population size and the relationships between genetic and geographical distances among samples collected from different tributaries and over time. Significant genetic differences were observed among most of the temporal samples collected from the same tributary, and analysis of molecular variance indicated that the temporal component explained about 10 times more of the genetic variation (1.98%) than did the spatial component (0.18%). Isolation by distance (IBD) was detected only in 2009. In addition, a significant correlation in population genetic structure was observed between samples collected in 2008 and those in 2009. In 2007, decomposed pairwise regression analysis identified one population as an outlier population and, following exclusion of the outlier sample, IBD was observed in 2007. This population is small and physically isolated by waterfall, in which the effective population size or effective number of breeders would be expected to be small. We found that fine‐scale genetic structure in masu salmon populations was temporally unstable, due perhaps to genetic drift in small isolated populations, temporal changes in environmental conditions (e.g. drought), and a combination of these factors. This study also highlights that the genetic structure among populations could easily be affected by temporal and/or sampling issues. Studies focused on temporal genetic structuring are likely to be important for conservation of species inhabiting unstable or isolated habitats such as freshwater fish.

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“…Most taxa still have little N b /N c data emerging, but sufficient data have become recently available in three fishes from the Salmoninae subfamily (Chinook salmon, Atlantic salmon and brook trout); these species form the basis of our quantitative analysis of N b /N c relationships. The studies examining these species have largely found positive relationships between N b and N c (e.g., Bernos & Fraser, ; Ferchaud et al., ; Perrier et al., ; Van Doornik, Waples, Baird, Moran, & Berntson, ; etc. ); we collated data across studies to produce models for converting N b to N c (and vice versa) in each species.…”

Section: Introductionmentioning

confidence: 99%

A critical assessment of estimating census population size from genetic population size (or vice versa) in three fishes

Yates

Bernos

Fraser

2017

Evolutionary Applications

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Technological and methodological advances have facilitated the use of genetic data to infer census population size (Nc) in natural populations, particularly where traditional mark‐and‐recapture is challenging. The effective number of breeders (Nb) describes how many adults effectively contribute to a cohort and is often correlated with Nc. Predicting Nc from Nb or vice versa in species with overlapping generations has important implications for conservation by permitting (i) estimation of the more difficult to quantify variable and (ii) inferences of Nb/Nc relationships in related species lacking data. We quantitatively synthesized Nb/Nc relationships in three salmonid fishes where sufficient data have recently accumulated. Mixed‐effects models were analysed in which each variable was included as a dependent variable or predictor term (Nb from Nc and vice versa). Species‐dependent Nb/Nc slope estimates were significantly positive in two of three species. Variation in species slopes was likely due to varying life histories and reinforce caution when inferring Nb/Nc from taxonomically related species. Models provided maximum probable estimates for Nb and Nc for two species. However, study, population and year effects explained substantial amounts of variation (39%–57%). Consequently, prediction intervals were wide and included or were close to zero for all population sizes and species; model predictive utility was limited. Cost‐benefit trade‐offs when estimating Nb and/or Nc were also discussed using a real‐world system example. Our findings based on salmonids suggest that no short cuts currently exist when estimating population size and researchers should focus on quantifying the variable of interest or be aware of caveats when inferring the desired variable because of cost or logistics. We caution that the salmonid species examined share life‐history traits that may obscure relationships between Nb and Nc. Sufficient data on other taxa were unavailable; additional research examining Nb/Nc relationships in species with potentially relevant life‐history trait differences (e.g., differing survival curves) is needed.

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Making sense of the relationships between Ne, Nb and Nc towards defining conservation thresholds in Atlantic salmon (Salmo salar)

Cited by 52 publications

References 79 publications

Estimating the effective number of breeders from single parr samples for conservation monitoring of wild populations of Atlantic salmon Salmo salar

Estimating the effective number of breeders from single parr samples for conservation monitoring of wild populations of Atlantic salmon Salmo salar

Short‐term temporal instability in fine‐scale genetic structure of masu salmon

A critical assessment of estimating census population size from genetic population size (or vice versa) in three fishes

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