Population dynamics of elusive species: The case of the common dolphin in the North-East Atlantic Ocean

• Main Author: Rouby, Etienne
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Observatoire PELAGIS UMS 3462 (PELAGIS), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Institut national des sciences de l'Univers (INSU - CNRS)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), La Rochelle Université, Vincent Ridoux, Matthieu Authier
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2022
• Subjects: Demography; Marine mammals; Megafauna; Population dynamics; Bycatch; Management; Bayesian statistics; Cross-sectional monitoring; Age-at-death; Conservation biology; Strandings; Captures accidentelles; Gestion; Statistiques Bayésiennes; Suivi transversal; Âge à la mort; Biologie de la conservation; Échouages; Démographie; Mammifères marins; Mégafaune; Dynamique des populations; [SDV]Life Sciences [q-bio]; North East Atlantic
• Online Access: https://theses.hal.science/tel-03878173; https://theses.hal.science/tel-03878173/document; https://theses.hal.science/tel-03878173/file/PhD_thesis_Rouby_Etienne.pdf

Elusive species are notoriously difficult to monitor individually and therefore it is difficult to estimate their anthropogenic mortality and to implement management policies. As an elusive species, the common dolphin, Delphinus delphis is a good example of these conservation challenges. The North-East Atlantic population is affected by bycatch that threatens its viability. However, demographic information on this population is very limited and our understanding of the spatio-temporal structure and dynamics of bycatch is insufficient to set appropriate management objectives. This project aims to determine the current status of this common dolphin population with regard to conservation objectives in European waters with a focus on the Bay of Biscay. First a flexible vital rates estimation approach has been developed in order to highlight variations in vital rates over time and the effects of covariates while taking into account individual heterogeneity. Second, using such a methodological approach through a cross-sectional monitoring, allowed us to highlight both the temporal variations of the population vital rates and the impact of bycatch on the common dolphin population demography. The population is not viable and the population growth rate seems to have deteriorated since the mid 2000's. Third, using biased data from on-board observers, the number of incidental catches on a weekly basis was quantified for ten ICES sub-area over sixteen years. Fourth, the resulting vital rates combined with bycatch estimates finally allowed the production of sustainable bycatch thresholds through a Management Strategy Evaluation approach in line with the European conservation objective. Les espèces élusives sont difficiles à suivre individuellement et il est difficile d'estimer leur mortalité ce qui freine la mise en place de politiques de gestion. En tant qu’espèce élusive, le dauphin commun, Delphinus delphis présente des enjeux de conservation importants. La population Atlantique Nord-Est est affectée par les captures ...