Blue whale foraging and movement ecology

This archive contains data used in a study of the movement and foraging ecology of blue whales in the eastern North Pacific, specifically the Monterey Bay region off central California, USA. The study was published in Ecology Letters in 2022 and is entitled, “Oceanic giants dance to atmospheric rhythms: Ephemeral wind-driven resource tracking by blue whales.” As of this writing, the article does not yet have a DOI. The published analyses were conducted in MATLAB. However, to make the data and reproducibility of analyses more widely accessible, both data and processing code have been translated into R for this archive. 1) Acoustic vector sensor (AVS) data from the MARS observatory Annual periods of blue whale acoustic presence were analyzed across two years to examine the directional distribution of whale call origin around the MARS cabled observatory. Quality controlled data include the time, bearing, and call index of all manually validated seconds for which the blue whale B-call index exceeded a value of 1.25. Analysis results from these data appear in Figures 4 and 5 of the paper. The data files are AVS_2019-2020.RData and AVS_2020-2021.RData, and the example processing code is AVSprocessing.R. 2) Modeled received levels at the MARS observatory The geographic domain over which received signal is sufficient to reliably estimate the direction of blue whale B-call origin from the MARS cabled observatory was approximated by modeling of acoustic transmission loss. These data appear in Figure 2C of the paper. Model results represent received level (underwater dB) at the MARS cabled observatory, assuming appropriately specified intensity, depth, and frequency of the sound source (blue whale B call) and oceanographic physical conditions during the time of year when blue whale calling is most active in the study region. The data file is ModeledReceivedLevel.RData, and the example processing code is ModeledReceivedLevelPlot.R. 3) Animal-borne tag data Data from a biologging tag deployed on a blue whale were used to validate an acoustic vector sensor on the MARS observatory. These data appear in Figure 3 of the paper and include information about whale behaviors (diving, calling, lunge feeding) and surface position from GPS. In addition to data on identified behavioral events, underlying hydrophone and accelerometer data used to identify behaviors during the period of matchup with MARS AVS data are included. The data file is Tag_bw191101-70.RData, and the example processing code is Tag_bw191101-70plot.R. 4) Forage species aggregation data The area scattering (sa) within forage species’ patches in the upper 200 m above the MARS observatory, presented in Figure 5E of the paper, are in the file MARS_sa.RData.