Collaborative humpback whale study continues in Hawaiian waters
Currently, the research team is studying the humpback whales now in waters off Maui. During summers, the team examines the same individual whales in feeding grounds off Southeast Alaska.
Humpback whales are back in Hawaiian waters after their fall migration from along the Northern Pacific rim, and a new long-term research project into their condition and health continued last month in waters off Maui. During summers, the research team examines the same individual whales in feeding grounds off Southeast Alaska.
The Marine Mammal Laboratory at the University of Hawai‘i at Hilo, founded by Adam Pack, who holds a joint appointment in the departments of psychology and biology, last month continued its collaborative research on humpback whale health with researchers from Hawai‘i and Alaska. On the team with Pack are Lars Bejder and Martin van Aswegen of the Marine Mammal Research Program at UH Mānoa, Jens Currie and Stephanie Stack of the Pacific Whale Foundation, Andy Szabo of Alaska Whale Foundation, Shannon Atkinson of University of Alaska, Fairbanks, and Kristi West of Hawai‘i Pacific University.
“Our goal is to learn about the physical and reproductive health of the Hawai‘i distinct population segment of North Pacific Humpback Whales by measuring how whale body condition, fertility levels, and indicators of stress change while calves are nursing and other whales are fasting over the course of a breeding season,” says Pack.
The team also examines how these same parameters compare with those from the same whales in the feeding grounds off Southeast Alaska as measured by van Aswegen, Bejder, and Szabo.
Through the long-term continuous monitoring of the whales, threats or stressors to the population are identified to provide science-based recommendations on mitigation strategies and contribute to adaptive management.
The Pacific Whale Foundation explains that the Hawai‘i Distinct Population Segment of humpback whales undertake one of the longest migrations of any animal, travelling between cooler, productive foraging grounds in the waters around Russia, Alaska, and western Canada to the warmer, tropical breeding grounds in Hawai‘i. Recent observations in Hawai‘i and Southeast Alaska have revealed declines in sighting rates of humpback whales, with a 50-75 percent decrease reported between 2013 and 2018. Despite the widespread popularity of humpback whales, the species continues to face several threats relating to human activities and ecosystem health, which is magnified by their preferred use of coastal habitats.
Continuous long-term monitoring is an effective research method to determine potential population changes and better predict and monitor the impacts of various stressors. By monitoring trends in the numbers of whales, their distribution, health and population status, the researchers can better inform management practices. Currently, in the leeward waters off Maui, the team is collecting a variety of data to gain a broad understanding of both individuals and the population at large using photo identification, tissue samples, and body condition metrics captured through drone imagery.
“The work involves a true team effort and incredible coordination, especially amidst the pandemic,” says Pack. In order to accomplish the work safely this year, neighbor island team members receive a negative PCR [COVID-19] test prior to Maui, while those living on Maui are also tested. The team is being kept small with no volunteers, and everyone wears masks while on the boat and out in public. The team also forms tiny research team covid-protected bubbles at all field houses.
Pack explains that after the team sights a whale pod and determines its composition, van Aswegen from UH Mānoa, (whose dissertation much of these data will comprise), along with Pacific Whale Foundation researchers, launch a drone that hovers over each whale when it surfaces to measure its body condition.
Above video, the research team uses drones that hover over each whale when it surfaces to measure its body condition. This footage was collected in 2019.
“Simultaneously, we give the whales temporary names based on the unique shapes of their dorsal fins, allowing us to link all streams of data to a named whale, and we take tail fluke identification images of individual whales when they dive,” explains Pack. “Once the drone returns and we can recognize the individual whales by sight, I carefully extract a tiny piece of blubber and skin from each whale using an arrow with a sterile stainless-steel tip projected from a cross-bow.”
Thus far, the researchers have gathered over 250 tail fluke images, measured over 270 individual whales, and collected over 65 biopsy samples.
“The preliminary results are providing important insights into the rates of maternal energy exchange as fasting moms lose body condition while their nursing calves grow, how male and female fertility levels vary as a function of body size, social role and reproductive condition, and how we might be able to detect through tissue samples whales whose health or well-being have been compromised,” says Pack.
In March, Pack will be back in Maui waters with the team for the second half of the humpback whale breeding season to identify, measure, and obtain new samples from individuals sighted earlier in the season who have been fasting or nursing during the interim.
Pack says that in this well-orchestrated research collaboration, each team member and each piece of data plays a vital role. His primary roles in the field are in obtaining biopsy samples for steroid hormone, genetic, and health analyses, and in obtaining fluke identifications and comparing these against his lab’s catalog to determine individual life histories and minimum ages. His Marine Mammal Lab’s humpback whale archival catalog now numbers over 23,000 images of humpback whales from the Hawai‘i Distinct Population and constitutes one of the largest archives of humpbacks in the world.
The biopsy sample data are analyzed at the labs of Pack’s colleagues at University of Alaska Fairbanks and Hawai‘i Pacific University.
“Then, back in my UH Hilo Marine Mammal Lab, I take the analyzed steroid hormone data and examine how testosterone, progesterone, and stress hormones vary for individual whales in various behavioral roles, body sizes, and reproductive conditions as well as those who have had long residency periods within a season in Hawai‘i, thus losing body condition.
All research is conducted under Federal Research Permits 19655, 21321, and 21476, as well as Part 107 authorization from the Federal Aviation Administration.
Story by Susan Enright, a public information specialist for the Office of the Chancellor and editor of UH Hilo Stories. She received her bachelor of arts in English and certificate in women’s studies from UH Hilo.