MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14654

ABSTRACT: The innovation of new foraging strategies allow species to optimize their foraging in response to changing conditions. Humpback whales provide a good study species for this, as they utilize multiple novel foraging tactics across population in diverse environments. Bubble-net feeding (BNF), commonly seen in the Northern Hemisphere, has emerged as a foraging innovation in the past twenty years within the Western Antarctic Peninsula. Using sightings data from 2015-2023, we found BNF present in every study year, with an annual average of 30% of foraging sightings. This was supplemented with 26 animal-born tags deployed over the same study period. Of these tags, 12 detected instances of BNF with BNF making up an average of 19% of lunges detected compared to other foraging tactics. BNF sightings had seasonal trends, as it was observed significantly more often at the beginning of the feeding season (January) before declining. BNF group sizes (mean = 3.41) were significantly larger compared to non-BNF surface feeding (mean = 2.21). This is consistent with BNF in the Northern Hemisphere, which also appears to primarily be a group foraging strategy. The seasonal pattern and relatively recent emergence of BNF suggests that its use is likely tied to specific environmental conditions, which should be investigated by comparing its use with specific variables such as prey density and light availability. The social transmission of novel foraging strategies across other populations further suggests that the prevalence of this strategy likely occurs through social learning.