Automated association of fin whale calls for localization using distributed acoustic sensing

Distributed Acoustic Sensing (DAS) on submarine cables is an untapped resource for monitoring marine mammals. The high spatial coverage and resolution of DAS data require specialized automated methods. In November 2021, the Ocean Observatories Initiative (OOI) Regional Cabled Array (RCA) collected DAS data including fin whale calls from an experiment offshore of central Oregon using two nearshore cable sections (65 and 95 km long) with sampling rates up to 1 kHz. This study presents an automated method for associating and localizing fin whale call detections of the OOI RCA. The method employs a grid search approach to associate acoustic arrival times between cables and multiple calling individuals, utilizing data from one or both cables depending on detection availability. Noisy call associations are enhanced through Gabor filtering of detections and spatial windowing on the farthest cable sections. Localization is performed using a weighted least squares inversion. Five ten-minute subsets of detection data were manually annotated to compute precision, recall, and F1-scores. The method enhanced with a far spatial window achieves recall values of 0.92-0.94 with low precision (0.3), which can be mitigated by subsequent track formation. These findings highlight the potential of submarine cable DAS for continuous, large-scale marine mammal monitoring.