Delayed response to environmental conditions and infra-seasonal dynamics of the short-beaked common dolphin distribution

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.

Disciplines

Biological oceanography

Keywords

Common dolphins, Bay of Biscay, Winter, Simulation, Temporal lag, Dynamic species distribution modelling

Location

48N, 44S, -5E, 0W

Devices

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:

  • functions: the folder contains all the functions necessary for running the R scripts.
  • data: 
    • Map files: land and isobath files used in the codes
    • Surveys files: there is two files for each surveys, one for the effort (5km-long segments) and one for the observations
    • Variables: raster stacks of all environmental conditions considered and used in the analyses.
  • scripts : the folder contains the nine scripts to run all the analyses described in the paper. Titles are self-explanatory.
  • scripts results: this folder is empty for now, but is to be populated when running the codes.

Data

FileSizeFormatProcessingAccess
Archive file containing data and codes for the analyses described in Lambert et al. 2022 RSOS
158 Mozip archiveProcessed data
How to cite
Lambert Charlotte, Authier Matthieu, Blanchard Ariane, Dorémus Ghislain, Laran Sophie, Van Canneyt Olivier, Spitz Jérôme (2022). Delayed response to environmental conditions and infra-seasonal dynamics of the short-beaked common dolphin distribution. SEANOE. https://doi.org/10.17882/86805
In addition to properly cite this dataset, it would be appreciated that the following work(s) be cited too, when using this dataset in a publication :
Lambert C., Authier M., Blanchard A., Dorémus G., Laran S., Van Canneyt O., Spitz J. (2022). Delayed response to environmental conditions and infra-seasonal dynamics of the short-beaked common dolphin distribution. Royal Society Open Science, 9 (11). https://doi.org/10.1098/rsos.220379

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