Johnson HD, Davies KTA, Taggart CT, Baumgartner MF. (2025). Using ocean gliders to characterize baleen whale habitat in the Northwest Atlantic. Marine Ecology Progress Series 764:189-211. https://doi.org/10.3354/meps14832

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 × 60 km), shallow (less than 180 m) basin located about 40 km seaward of SW Nova Scotia, Canada. Data were collected from 13 fall (August-November) glider surveys of the basin over an 8 yr 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 for fin, sei, and right whale occurrence and depth. They also showed that right whale occurrence in August-September 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. Although exploratory, our results demonstrate the utility of profiling gliders for making inferences about baleen whale habitats.

Johnson HD, Davies KTA, Durette-Morin D, Carr MK, Franklin KJ, Brown MW, Hamilton PK, Knowlton AR, Taggart CT, Baumgartner MF. (2025). North Atlantic right whale (Eubalaena glacialis) habitat in the southern Gulf of St Lawrence. Endangered Species Research 58:359-379. https://doi.org/10.3354/esr01456

The distribution of North Atlantic right whales (hereafter ‘right whales’) has shifted since 2010, as exemplified by the decreased use of several habitats in the Gulf of Maine, lower Bay of Fundy, and Scotian Shelf, and increased occupancy of the southern Gulf of St. Lawrence (sGSL). The goal of this study was to characterize right whale feeding habitat in the sGSL region. We conducted opportunistic oceanographic sampling in the presence and absence of right whales in July and August over 3 yr (2017-2019). Each oceanographic station was typically comprised of a depth-integrated ring net tow and 2 vertical profiles with a conductivity-temperature-depth instrument and optical plankton counter. Of the calanoid copepod taxa, small copepods (e.g. Centropages spp., Pseudocalanus spp.) were numerically dominant at all stations where data were available, but Calanus finmarchicus was also abundant, while C. hyperboreus comprised most of the biomass. Net-derived abundance of late-stage C. hyperboreus and total biomass were significantly greater at stations where right whales were detected. Logistic regression analysis suggested that a higher probability of right whale detection was associated with a thicker bottom mixed layer and abundant patches of late-stage C. hyperboreus near the seafloor. These results offer insights into the vertical distribution and quantity of prey, the quality of the sGSL as a right whale foraging habitat, and the associated implications for right whale recovery.