Aligning the seasonal migration of North Atlantic Right Whales with oceanic features
Creators: name: Dreyfus, Courtney
Publisher: name: No Publisher Supplied
Year: 2022

description: While baleen whales have been migrating through the oceans for millions of years, more recent human activity has heavily impacted their populations. The population of North Atlantic right whales (NARW) has been in rapid decline compared to other baleen whale species. To counteract this, there has been a recent push in science and conservation to understand how the ocean environment influences the behaviors of these whales. The purpose of this study is to see how oceanic features factor in the migratory patterns of North Atlantic right whales off the coast of New Jersey. The study was conducted in an offshore wind lease area off the south coast of New Jersey as part of the ECO-PAM Project. ECO-PAM, funded by Ørsted OceanWind, is a collaboration between Rutgers University, Woods Hole Oceanographic Institution, and the University of Rhode Island. Autonomous vehicles equipped with oceanographic and ecological sensors simultaneously mapped whale detections in the context of physical ocean features. Slocum gliders, deployed in month-long missions between the summer of 2020 and the spring of 2022, used digital acoustic monitoring instrument (DMON) passive acoustic monitors to detect NARW relative to concurrent temperature, salinity, density, oxygen concentration, and chlorophyll observations. The oceanic variables from these deployments were mapped relative to the DMON acoustic detection of NARW. The standard deviation, average, median, and percentile ranges for all ocean variables were calculated for the detection time periods and compared to data collected throughout each deployment. Additionally, satellite derived ocean fronts based on MODIS Aqua 8-Day 1-km Composite Northwest Atlantic provided by the University of Delaware were also mapped relative to NARW observations. Histograms of data-derived fronts were used to evaluate the proximity of these fronts at the detection times compared to the fronts encountered by the glider during times of no detections.Results indicate that the presence of NARW begins near the coast in late fall, transitions offshore in the winter, with no detections between mid-spring through mid-fall. Findings for temperature, salinity, oxygen concentration, density and chlorophyll aligned with the seasonal changes associated with fall mixing and atmospheric changes but showed no significance to NARW distribution and behavior. While ranges in temperature did not vary greatly, congregations of NARW in cooler waters inshore in the fall and warmer waters offshore during the winter implied a tendency for these animals to favor thermal gradients. The frontal analysis suggests that NARW favor areas with stronger fronts in the fall near shore and stronger fronts offshore in the winter.Analysis from the gliders, acoustics, and satellites highlights the potential for oceanic feature mapping to better understand NARW migration pathways and conduct mitigation strategies. This research serves as an example of the new insight gained when integrating concurrent oceanic and ecological data, and demonstrates how dynamic mapping through autonomous systems could support whale-friendly maritime activity in and around planned offshore wind lease areas in the Mid Atlantic Bight.