Dear colleagues, On behalf of my co-authors, I am excited to announce the publication of the following open access article in Royal Society Open Science : http://dx.doi.org/10.1098/rsos.191104 <http://dx.doi.org/10.1098/rsos.191104> Pectoral herding: an innovative tactic for humpback whale foraging Citation: Kosma MM, Werth AJ, Szabo AR, Straley JM. 2019 Pectoral herding: an innovative tactic for humpback whale foraging. R. Soc. open sci. 6: 191104. http://dx.doi.org/10.1098/rsos.191104 Abstract: Humpback whales (Megaptera novaeangliae) have exceptionally long pectorals (i.e. flippers) that aid in shallow water navigation, rapid acceleration and increased manoeuvrability. The use of pectorals to herd or manipulate prey has been hypothesized since the 1930s. We combined new technology and a unique viewing platform to document the additional use of pectorals to aggregate prey during foraging events. Here, we provide a description of ‘pectoral herding’ and explore the conditions that may promote this innovative foraging behaviour. Specifically, we analysed aerial videos and photographic sequences to assess the function of pectorals during feeding events near salmon hatchery release sites in Southeast Alaska (2016–2018). We observed the use of solo bubble-nets to initially corral prey, followed by calculated movements to establish a secondary boundary with the pectorals—further condensing prey and increasing foraging efficiency. We found three ways in which humpback whales use pectorals to herd prey: (i) create a physical barrier to prevent evasion, (ii) cause water motion to guide prey towards the mouth, and (iii) position the ventral side to reflect light and alter prey movement. Our findings suggest that behavioural plasticity may aid foraging in changing environments and shifts in prey availability. Further study would clarify if ‘pectoral herding’ is used as a principal foraging tool by the broader humpback whale population and the conditions that promote its use. The paper can be accessed freely using the following link: http://dx.doi.org/10.1098/rsos.191104 <http://dx.doi.org/10.1098/rsos.191104> Please feel free to contact me at madison.kosma@gmail.com <mailto:madison.kosma@gmail.com> if you have any queries. Sincerely, Madison Kosma Madison M. Kosma Masters Student, College of Fisheries and Ocean Sciences Juneau Fisheries Division, University of Alaska Fairbanks mobile: (231) 282.0061 email: mmkosma@alaska.edu