Passive Acoustic Monitoring Reveals Sustained Presence of Humpback Whales (Megaptera novaeangliae) in Batemans Bay, New South Wales, Australia, During Migration Season

Résumé fourni par la source

Abstract Humpback whales ( Megaptera novaeangliae ) undertake long-distance annual migrations to access seasonally optimal habitats for feeding and reproduction. However, shifts in migration timing have been documented across multiple populations worldwide. Under rapid environmental change and increasing coastal development, there is growing concern that long-distance migrants may arrive in critical habitats outside favourable ecological windows. Along Australia’s east coast, the E1 subpopulation migrates between Antarctic feeding grounds and Coral Sea breeding areas, yet substantial geographic gaps remain in monitoring their occurrence, particularly along their migration route. To address this, a passive acoustic recorder was deployed throughout the migratory period in Batemans Bay, NSW from May to September 2024. Across 102,960 min of acoustic monitoring, humpback whale vocalisations were detected in 70% of monitored hours, spanning 87% of monitored days. The first detection occurred on 19 May, with sustained daily presence from 22 May through late September. Acoustic presence increased rapidly from late May and peaked in early August, before increasing again towards the end of the monitoring period in late September. Detections were significantly higher at dawn (73%), dusk (73%), and night (80%) compared to day (62%). These findings provide the first systematic account of humpback whale occurrence in Batemans Bay and update current understanding of humpback whale migration timing along the NSW south coast, including the timing of the northward migration after more than a decade. The consistently high acoustic presence observed throughout the monitoring period indicates that Batemans Bay represents an important migratory habitat for E1 humpback whales travelling along Australia’s east coast.

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