Tracking baleen whale calls in the Lower St. Lawrence Seaway, Canada, using land seismometers

The Lower St. Lawrence Seaway (LSLS) is part of a major marine shipping corridor in eastern Canada, and also an essential feeding ground for fin whales and blue whales. Understanding the whale migration and habitat usage in the LSLS is critical for informing conservation policies that minimize noise pollution and risk of collision to the whale populations. In this study we utilize continuous recordings of six broadband seismometers located on the north and south shores of the St. Lawrence River to characterize the frequency range, recurrence interval and duration of fin and blue whale calls. We further use the whale call detections to quantify their spatial and temporal variations along the LSLS between February 2020 and January 2022, with the caveat that the detection range at these land stations is probably limited to a few kilometers due to energy loss along the seismic wave travel paths through multiple interfaces. We identified higher whale call detection rates at stations near the northwest of St. Lawrence Gulf than the upstream Estuary, suggesting possible influences of ocean currents and ice conditions. Whale calls are detected year around, with majority in the fall/winter months (September to February), implying seasonal and annual variations that may be influenced by climate change. We are currently analyzing recordings from a temporary deployment of 48 nodal seismometers, at 10-km average spacing, along the shorelines of the LSLS between September-October 2023, to further quantify the spatial patterns of whale calls and identify possible linkages to coastal bathymetry, ocean currents and preferential diets for the baleen whales.