Temporal acoustic presence of Southern Right Whales off Elephant Island

Knowledge of wildlife presence in Antarctica is patchy because the climate and landscape make it inaccessible to humans for many months of the year. Passive acoustic monitoring (PAM) offers a solution by collecting continuous, long-term acoustic data on vocal species, such as marine mammals, independent of the weather and without human interference. The southern right whale (Eubalaena australis; SRW) is a baleen whale found in the Southern Hemisphere that was hunted to near extinction, according to the International Whaling Commission (IWC). SRWs produce a unique species-specific sound called the "upcall" that can be identified in acoustic recordings. Detecting their upcalls in acoustic recordings can tell us important information about their distribution and temporal presence. PAM was used to sample audio recordings from Elephant Island, an island off the Antarctic Peninsula, from 2013 onward. This study analyzes approximately 3 years (2013, 2017, and 2019/2020) of that acoustic data. A detector was created from 3 upcall acoustic templates to automatically scan all of the audio recordings to identify the upcall detections using binary point matching. The results indicate that SRWs had the highest presence off Elephant Island in 2013. There were significantly fewer upcall detections in 2019/2020. Upcalls were detected throughout the whole year, with more detections from January to April and July. Additionally, there was an evident bimodal hourly diel distribution, with peaks at 11 am and 11 pm. The winter season saw a higher peak at 11 am, and the summer season saw a higher peak at 11 pm. This study is important in bioacoustics because automatic detection saves work time. Further research utilizing multiple methodologies, such as cetacean acoustic tags with GPS and accelerometers, would help understand the factors that affect the temporal presence of SRWs and if these have implications for SRW conservation.