Assessment of Southern Right whale (Eubalaena australis) acoustic presence off northwestern Chilo? Island and Arauco Gulf, Chile
Constanza Rojas-Cerda, Susannah Buchan, Barbara Galletti-Vernazzani, Ivan Perez-Santos
The southern right whale from the Southeast Pacific population (Eubalaena australis) is a currently Critically Endangered sub-population according to the IUCN. In 2012, the International Whaling Commission adopted a Conservation Management Plan for this stock and since 2016 the Scientific Committee has supported a Passive Acoustic Monitoring (PAM) project with the aim of identifying possible breeding areas along the coast of Chile-Peru. Within the framework of this project, one year of continuous acoustic data was collected from the northwestern of Chiloé Island (2018-2019), and 5 months of recordings from the Arauco Gulf (2019-2020). These recordings were analyzed using an automatic detector specially developed under this project for right whale upcall vocalizations in the LFDCS software. The detections were reviewed and validated by an analyst. Off Chiloé, we found 189 true positive detections in the 2018-2019 period, with calls present during the austral summer, autumn and winter with no clear seasonal trend. While in the Arauco Gulf, no true positive detections were found. There were two peaks of detections off Chiloé, one in December 2018 with high vocalization rates during 2 days, and the second in March 2019 with 8 days of acoustic presence. Gunshots were found along with upcalls during March 2019. The presence of gunshots is of relevance, because they have been associated with mating or agonistic behavior between males in other populations. These presence of upcalls in almost all seasons suggest that northwestern ChiloéIsland is potentially used by individuals as a non-migratory habitat or could be the reflection of a population so small that seasonality cannot be detected. On the other hand, the short recording period in the AraucoGulf means that southern right whales may have been missed so better temporal coverage at this site is necessary.