MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14832

ABSTRACT: Characterizing baleen whale habitat is challenging because of the difficulty in obtaining sufficient spatially and temporally concurrent in situ observations of whales and oceanographic conditions. We collected a multi-year series of concurrent whale detections and high-resolution oceanographic measurements from Slocum ocean gliders to evaluate baleen whale habitat associations. The study area was Roseway Basin, a relatively small (30 x 60 km), shallow (<180 m) basin located ~40 km seaward of SW Nova Scotia, Canada. Data were collected from 13 fall (Aug - Nov) glider surveys of the Basin over an eight-year period (2014 - 2021). Gliders collected profiles of salinity and temperature as well as audio to detect and classify whale sounds. Acoustic analysis revealed spatial, diel, and within-season patterns in whale detections. Whale occurrence and a suite of oceanographic variables were computed in 20-km grid cells in each month and year of the study (n = 267). Descriptive and statistical (logistic regression) analyses were used to explore associations between the occurrence of each species and depth, topographic relief, water column stratification, current speed, and bottom mixed layer thickness and density. Results suggested strong, positive associations of fin, sei, and right whale occurrence and depth. They also showed that right whale occurrence in Aug - Sep was associated with a well-stratified water column overlying a thick, dense bottom mixed layer, consistent with conditions known to have a role in aggregating their copepod prey. Though exploratory, our results demonstrate the utility of profiling gliders for making inferences about baleen whale habitats.