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

• Published in: Journal of Fish Biology
• Main Authors: Bacles, Cécile, Bouchard, Colin, Lange, Frédéric, Manicki, Aurélie, Tentelier, Cédric, Lepais, Olivier
• Other Authors: Ecologie Comportementale et Biologie des Populations de Poissons (ECOBIOP), Institut National de la Recherche Agronomique (INRA)-Université de Pau et des Pays de l'Adour (UPPA), This project was funded by the Agence Française pour la Biodiversité, project 2016–18 A13 ‘NombReEff. Estimation du nombre de reproducteurs efficaces un nouvel indicateur de l’état des populations’.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: colony; genetic monitoring; Nb; population genetics; sibship reconstruction; young-of-the-year; salmon; atlantic; nature conservation; salmo salar; reproducteur; genetique des populations; colonie; population sauvage; conservation; nivelle; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Atlantic salmon; Salmo salar
• Online Access: https://hal.archives-ouvertes.fr/hal-01716615; https://doi.org/10.1111/jfb.13537

International audience This study assesses whether the effective number of breeders (Nb) 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. Nb 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 Nb 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. Nb estimated in autumn for S. salar in the River Nivellewas lowand 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. Nb 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 Nb 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.