Sea Ice and Whales from Space: The Feasibility of Using Satellite Imagery for Monitoring Beluga Whales in Winter

Very-high-resolution (VHR) satellite imagery has expanded the scale at which researchers can monitor marine mammals in remote regions and improved monitoring efforts in data-deficient areas. Relatively little is known about beluga whale (Delphinapterus leucas) distribution in their wintering grounds, due partly to the unpredictability of sea ice formation and limited accessibility. VHR satellite imagery has been used successfully to estimate the abundance of summering beluga whales; however, the feasibility of tasking VHR satellite imagery in the winter and determining the detectability of beluga whales amongst sea ice have not been formally assessed. Our objective was to assess the feasibility of acquiring VHR satellite imagery in the winter and whether beluga whales could be reliably distinguished from sea ice in the imagery. Our study focused on beluga whale populations that are winter residents within James Bay and Cumberland Sound, occupying nearshore open water and ice leads in the winter. Two images were collected in Cumberland Sound covering known beluga whale wintering grounds in February and March 2022 encompassing 745 km2, with ice covering >75% of the image, and three images were acquired within James Bay from January to March 2024 spanning over 5700 km2, with ice covering >86% of the survey area. We observed 0 certain and 294 uncertain detections, suggesting that current satellite imagery resolutions are too low for confidently detecting beluga whales amongst densely packed ice. High-definition sharpening to 15 cm reduced the number of uncertain detections, but we were still unable to identify any certain whales. Continued advancements in imagery resolution are required to distinguish beluga whales from sea ice and improve year-round beluga whale monitoring.