Source levels and calling rates for humpback whale (Megaptera novaeangliae) non-song vocalizations in Glacier Bay Alaska

Abstract

Marine resource managers in Glacier Bay National Park, Alaska, have been tasked with assessing the impact of vessel noise on marine mammal species. Humpback whales (Megaptera novaeangliae) are a highly vocal baleen whale that forage between spring and fall in Park waters. While calling rates and source levels for this species have been described on breeding grounds and migratory corridors, these fundamental acoustic parameters have not been thoroughly described on foraging grounds, and have never been empirically measured in the North Pacific. Using a three-element hydrophone array deployed in the Beardslee Island complex of Glacier Bay during the 2015 summer foraging season humpback whale “whup” and “growl” calls were localized and source levels were calculated. Array recordings were paired with shore based abundance estimates from the same period and calling rates (calls per whale per hour) were estimated. Known calling rates and source levels are essential for developing detection algorithms, masking metrics, and determining communication space on this historically important foraging ground.