Aerial survey perspectives on humpback whale resiliency in Maui Nui, Hawaiʻi, in the face of an unprecedented North Pacific marine warming event

• Published in: Marine Mammal Science
• Main Authors: Mobley Jr., Joseph R., Deakos, Mark H., Pack, Adam A., Bortolotto, Guilherme A.
• Other Authors: University of St Andrews. School of Biology
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2024
• Subjects: Climate change; Conservation; Density; Distance sampling; Humpback whales; Megaptera novaeangliae; Pacific Marine Heatwave (PMH); Resilience; GE Environmental Sciences; QL Zoology; NDAS; SDG 13 - Climate Action; SDG 14 - Life Below Water; AC; MCC; GE; QL; Humpback Whale; Alaska
• Online Access: https://hdl.handle.net/10023/29534; https://doi.org/10.1111/mms.13018

Funding: The authors are grateful to our sponsors of the 2019–2020 aerial surveys including Dave Jung of Hawaii Ocean Project, Whale Trust, University of Hawaiʻi at Hilo, and The Dolphin Institute. Nina Forsyth was instrumental in organizing a GoFundMe drive that provided additional funding. After decades of population growth, the central stock of the North Pacific population of humpback whales, known as the Hawaiʻi Distinct Population Segment (HDPS), was delisted from its endangered status in 2016. At that time, however, an unprecedented heating event, the Pacific Marine Heatwave (PMH) was already underway. The PMH coincided with reports of major declines of sightings of humpback whales, including calves of the year, on both the Hawaiian wintering grounds and the feeding grounds of Southeast Alaska. To examine the resiliency of the HDPS, we conducted aerial surveys of the high-density Maui Nui region immediately following the PMH event in 2019 and 2020, using distance sampling methods identical to those used in an earlier series (1993–2003). Results showed whale densities at or above those seen earlier, with mean density for 2020 highest overall. Crude birth rates (percent groups containing a calf) were similarly comparable to those recorded in the earlier series, with an increase from 2019 to 2020. Overall, results suggest the central North Pacific humpback whale population stock to be resilient in the face of this major climatic event. Peer reviewed