Passive Acoustic Monitoring Reveals Spatio-Temporal Distributions of Antarctic and Pygmy Blue Whales Around Central New Zealand

Effective management of wild animal populations relies on an understanding their spatio-temporal distributions. Passive acoustic monitoring (PAM) is a non-invasive method to investigate the distribution free-ranging species that reliably produce sound. Critically endangered Antarctic blue whales ( Balaenoptera musculus intermedia ) (ABWs) co-occur with pygmy B. m. brevicauda (PBWs) around New Zealand. Nationally, both are listed as “data deficient” due difficulties in access and visual sub-species identification. PAM was used distributions via specific song detections central Propagation models, incorporating ambient noise data, enabled comparison among recording locations different marine environments. ABW peaked during austral winter spring, indicating Zealand, South Taranaki Bight (STB) particular, migratory corridor for ABWs. Some calls were also detected breeding season (September October). PBW highly concentrated STB, particularly between March May, suggesting aggregation PBWs may occur here. Therefore, STB great importance whale. absent from parts but at east coast this time. Detection area models valuable when interpreting comparing locations. The results provide information required critically ABWs highlight relative Zealand