Determination of the conservation limit for Atlantic salmon (Salmo salar) : sensitivity analysis based on the case study of the Nivelle River (Basque Country, France)

• Main Author: Flais, Benjamin
• Other Authors: Institut Agro Rennes Angers, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), UMR ECOBIOP, 173 route de Saint-Jean-de-Luz, 64310 Saint-Pée-sur-Nivelle, Étienne Rivot, Étienne Prévost
• Format: Master Thesis
• Language: French
• Published: HAL CCSD 2022
• Subjects: Atlantic salmon; Nivelle; Conservation limit; Stock; Recruitment; SR relationship; Saumon atlantique; Limite de conservation; Recrutement; Relation SR; [SDV]Life Sciences [q-bio]; Salmo salar
• Online Access: https://dumas.ccsd.cnrs.fr/dumas-03868023; https://dumas.ccsd.cnrs.fr/dumas-03868023/document; https://dumas.ccsd.cnrs.fr/dumas-03868023/file/2022_Flais_Benjamin_SHA.pdf

The conservation limit (CL) is an important biological reference point for Atlantic salmon (Salmo salar). In this study the CL is the spawning abundance that controls the risk of low recruitment. The stock-recruitment (SR) relationship, at the heart of this definition, can be decomposed into several components: SR curve, process error, a priori knowledge of the SR model, measurement error. The main objective of this work is to analyze the sensitivity of CL's to these different components. Several types of SR curves and assumptions on the process error as well as different levels of a priori knowledge of the SR model are analyzed. To do this, a sequential approach is followed in order to limit the number of combinations to analyze. The impact of the measurement errors on the LC is analyzed following this sequential analysis on a preliminary selection of combinations. This work is carried out by means of a case study: the Atlantic salmon population of the Nivelle (Basque Country, France). In our case the LC can change radically depending on the representation of the different components of the SR relationship. Factor in the measurement errors does not seem to have a significant impact on the CL's. Finally, we discuss the importance of accurately analyzing the stochasticity of recruitment to determine CL's based on a control of the risk of low recruitment. La limite de conservation (LC) est un point de référence biologique important pour le saumon atlantique (Salmo salar). Dans cette étude la LC correspond à l’abondance de géniteurs permettant de contrôler le risque de faible recrutement. La relation stock-recrutement (SR), au coeur de cette définition, peut être décomposée en plusieurs composantes : courbe SR, erreur de processus, connaissance a priori du modèle SR, erreur de mesure. L’objectif principal de ce travail est d’analyser la sensibilité des LC’s à ces différentes composantes. Plusieurs types de courbes SR et hypothèses sur l’erreur de processus ainsi que différents niveaux de connaissance a priori du ...