Delayed response to environmental conditions and infra-seasonal dynamics of the short-beaked common dolphin distribution
|Temporal extent||2020-01-01 -2021-04-15|
|Author(s)||Lambert Charlotte1, 2, Authier Matthieu1, Blanchard Ariane1, Dorémus Ghislain1, Laran Sophie1, Van Canneyt Olivier1, Spitz Jérôme1, 2|
|Affiliation(s)||1 : CNRS - La Rochelle Université, UAR 3462, Observatoire Pelagis, F-17000 La Rochelle, France
2 : CNRS - La Rochelle Université, UMR 7372, Centre d’Etudes Biologiques de Chizé, F-79360 Villiers-en-bois, France
|Keyword(s)||Common dolphins, Bay of Biscay, Winter, Simulation, Temporal lag, Dynamic species distribution modelling|
Cetaceans adjust their distribution and abundance to encountered conditions across years and seasons, but we poorly understand such small-scale changes for many species, especially in winter. Crucial challenges yet weight on some populations during this season, such as the high levels of fisheries-induced mortality faced by the common dolphin (Delphinus delphis) in the North-East Atlantic shelves. For such species, comprehend the winter fine-scale dynamics is crucial. We aimed at identifying the dolphin distribution drivers within the winters 2020 and 2021, with a focus on determining the lag between changes in oceanographic conditions and in dolphin distribution. They were related with temporal delays specific to the nature and the cascading effects oceanographic processes had on the trophic chain. By determining the most important conditions and lags to dolphin distributions, we shed light on the yet poorly understood intrusions of dolphins within coastal waters during winter: they displayed a strong preference for the coastal-shelf waters front and extensively followed its spatial variations, their overall densities increasing over the period and peaking in March-April. The results presented here provided invaluable information on the winter distribution dynamics and should inform management decisions to help reducing the unsustainable mortalities of this species in fisheries by-catch.
|Utilisation||This work is based on three aerial surveys conducted in the Bay of Biscay in the winters 2020 and 2021: SPEE, CAPECET and SAMM II surveys, conducted by Observatoire Pelagis UAR 3462 CNRS-LRUniv.|
|Acknowledgements||This work was funded by the Office Français de la Biodiversité - Parc naturel marin de l'estuaire de la Gironde et de la mer des Pertuis (Gironde Estuary and Pertuis Sea Marine Nature Park; https://plan-gestion.parc-marin-gironde-pertuis.fr/) and the Région Nouvelle Aquitaine (contract AFB/2018/369 and contract OFB/20/0634), with support from the French Ministry in charge of the Environment.|
Archive of analysis code used in Lambert et al. 2022 Delayed response to environmental conditions and infra-seasonal dynamics of the short-beaked common dolphin distribution, RSOS.
This repository contains all data and codes necessary to replicate the analyses and results presented in the paper. It is organised as follows: