Preliminary assessment of the acoustic presence of multiple humpback whale (Megaptera novaeangliae) populations in the eastern Weddell Sea in 2011 and 2012
Male humpback whales are known to sing long, stereotyped songs which are thought to be population specific. The songs are largely produced on breeding grounds, and occasionally during migration and on feeding grounds. The eastern Weddell Sea is an Antarctic feeding ground which is thought to be seasonally visited by multiple humpback whale populations. However, the acoustic presence of different populations in the eastern Weddell Sea requires further investigation. The study sought to examine the acoustic presence of distinct humpback whale populations in the eastern Weddell Sea. The acoustic data were collected using one recorder deployed in the eastern Weddell Sea, and covered a time interval of 21 months. The data were visually and aurally inspected by human analysts. The preliminary analyses provided insights on the humpback whales acoustic presence, confirming a more plastic migratory behaviour as well as the strong difference of the seasonal acoustic presence. Furthermore, results highlighted the song building process characterized by the increase in length and complexity of the songs with the beginning of the Austral fall. Ultimately, the present findings indicated the acoustic presence of distinct humpback whale populations in the eastern Weddell Sea. However, due to the comparatively small acoustic data set resulting in low statistical power, more extensive research is warranted to define seasonality and acoustic presence of multiple populations of humpback whales in this region.