Investigating stock structure and trophic relationships among island-associated dolphins in the oceanic waters of the North Atlantic using fatty acid and stable isotope analyses

• Published in: Marine Biology
• Main Authors: Quérouil, Sophie, Kiszka, J., Cordeiro, A. R., Cascao, I., Freitas, L., Dinis, A., Alves, F., Santos, R. S., Bandarra, N. M.
• Other Authors: Instituto do Mar & Department of Oceanography and Fisheries - University of the Azores (IMAR-DOP), IMAR, Caractérisation et valorisation de la diversité ichtyologique pour une aquaculture raisonnée (CAVIAR), Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement IRD : UR226-Centre National de la Recherche Scientifique (CNRS), Department of Biological Sciences Miami, Florida International University Miami (FIU), Museau de Baleia da Madeira, museu da Baleia, Instituto Português de Investigação do Mar e da Atmosfera (IPMA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: OCEAN ATLANTIQUE; ATLANTIQUE ILES; MADEIRA; ACORES; [SDV.BID.EVO]Life Sciences [q-bio]/Biodiversity/Populations and Evolution [q-bio.PE]; North Atlantic
• Online Access: https://hal.ird.fr/ird-00841394; https://hal.ird.fr/ird-00841394/document; https://hal.ird.fr/ird-00841394/file/Querouil-al-MB-2-HAL.pdf; https://doi.org/10.1007/s00227-013-2184-x

International audience Short-beaked common dolphins (Delphinus delphis) and Atlantic spotted dolphins (Stenella frontalis) are the two most abundant cetacean species in the oceanic waters of Madeira and the Azores. They are of similar size, occur in similar habitats and are regularly observed in mixed-species groups to forage together. Genetic analyses suggested that, within each species, dolphins ranging around both archipelagos belong to the same panmictic population. We tested the hypotheses that (1) within each species, individuals from the two archipelagos belong to a single ecological stock; (2) between species, common and spotted dolphins have distinct trophic niches; using fatty acid (FA) and stable isotope (SI) analyses. Fatty acids and stable isotopes were analysed from 86 blubber and 150 skin samples of free-ranging dolphins, respectively. Sex-related differences were not significant, except for common dolphin FA profiles. In S. frontalis, FA and SI differences between archipelagos suggested that individuals belonged to different ecological stocks, despite the existence of gene flow between the two archipelagos. In D. delphis, differences were more pronounced, but it was not possible to distinguish between stock structure and a seasonal effect, due to differential sampling periods in the Azores and Madeira. Inter-specific comparisons were restricted to the Azores where all samples were collected during summer. Differences in FA proportions, noticeably for FA of dietary origin, as well as in nitrogen SI profiles, confirmed that both species feed on distinct resources. This study emphasizes the need for an integrated approach including both genetic and biochemical analyses for stock assessment, especially in wide-ranging marine top predators.