Investigating the impact of anthropogenic noise on humpback whale social calling behavior on a Southeast Alaskan foraging ground
The goals of this project are to [a] describe the role of social calls within the vocal repertoire of Southeast Alaskan humpback whales (Megaptera novaeangliae); [b] quantify biotic and abiotic contributions to the marine soundscape of Glacier Bay National Park; [c] calculate calling rates and critical source level estimates of humpback whale social calls; [d] assess changes in social calling behavior (calling rates, source levels, call repertoire) as a function of vessel noise.
PhD student Michelle Fournet's dissertation research investigates how social calls - non-song vocalizations produced by humpbacks across their migratory range - function as a form of communication on northern latitude foraging grounds, and seeks to assess what impact low-frequency vessel noise may have on humpback whales' ability to communicate. Humpback whales are a highly vocal migratory baleen whale whose social calling repertoire is comparatively understudied. Humpback whales worldwide produce social calls, but their role in singing behavior, social interactions, and foraging contexts, remains unknown. Further, as humpback whale populations increase these animals are increasingly likely to interact with vessels. Boats produce pervasive, broadband, low-frequency, noise that overlaps considerably with the humpback whale social calling repertoire. Michelle intends to assess whether low-frequency vessel noise masks humpback whale vocalizations while on their foraging grounds.
To achieve this goal under the guidance of Drs. Holger Klinck and Dave Mellinger, and in association with Chris Gabriele of the National Park Service, Michelle will deploy a four-hydrophone array within a historic humpback foraging ground in Glacier Bay National Park, Southeast Alaska. The hydrophone array will allow for vocalizing animals to be acoustically located underwater, and for critical acoustic parameters to be calculated. This coupled with visual data taken from a shore-based observing station will allow Michelle to determine the vocal and social behavior of humpback whales in both the presence and absence of vessel noise. This data will then be further analyzed for signs of altered behavior as a function of noise levels, and modeled to assess masking potential within the park. The results of this study will inform park managers, and marine resource managers, of the tangible impacts of vessel pressure on humpback whale communication.
Co-PI's: Christine Gabriele (NPS), Susan Parks (Syracuse University), Dave Mellinger (OSU/NOAA-PMEL), Jamie Womble (NPS)
Partners: Meghan Mckenna (NPS)