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Foundation collaborates with UH Manoa program to study humpback whale sightings decline

By Staff | May 2, 2019

MAALAEA – Earlier this year, Pacific Whale Foundation joined a collaborative project to quantify the bioenergetic demands of humpback whales migrating between Alaskan foraging grounds and Hawaiian breeding grounds.

Working with the University of Hawaii at Manoa Marine Mammal Research Program, University of Hawaii at Hilo, University of Alaska Fairbanks and the Alaska Whale Foundation, the project aims to identify potential factors contributing to the decline in observed sighting rates of humpback whales in Hawaii and Alaska.

In 2016, the distinct population segment of humpback whales in Hawaii were taken off the Endangered Species List. However, since then, sighting rates of humpback whales in Hawaii and southeast Alaska have dropped.

There is currently a lack of understanding of why humpback whale sighting rates have reduced.

The project will contribute to efforts investigating the possible causes of this recent trend focusing on relationships to changes in body condition and animal health.

The cost of migrating is a key parameter in determining a species’ life history strategy, and it may provide insight into a potential shift in life history strategy that could contribute to an increased understanding of the recent trends.

PWF’s role in this well-timed collaboration consists of connecting its long-term photo identification catalog that dates back to 1981 with UAV measurements, assisting with field sampling efforts and developing long-term datasets and analysis.

PhD students in the Marine Mammal Research Program at UH Manoa will apply expertise in utilizing drones and leading technology to measure whales.

“The collaboration with UH has been great,” said PWF Chief Scientist Jens Currie. “Working together allows you to utilize the expertise, knowledge and data that has been gathered by the various partners over the years to get a more holistic understanding of the population, approaching the question of whether recent trends in humpback whale sighting rates is related to their health.”

In January, the research was facilitated by Ultimate Whale Watch on Maui, which graciously hosted researchers for ten days on its vessel. The group completed 243 drone flights within the Hawaiian Islands Humpback Whale National Marine Sanctuary over 17 days with 150 humpback whales measured per month, including adults and sub-adults from a variety of group compositions, including single individuals, mother-calf-escort groups and competitive male groups.

Dr. Adam Pack, a UH Hilo professor, joined PWF and UH Manoa teams for intensive tissue sampling to utilize multiple data streams (drone measurements, biopsy samples and photo identification) to investigate possible links between humpback whale body condition, steroid hormones, lipid content and stable isotopes relative to demographics.

Over a three-day period, the team managed to biopsy sample approximately 20 humpback whales where body condition measurements, biopsy samples and fluke IDs were all collected.

UH Manoa Marine Mammal Research Program Director Dr. Lars Bejder said, “This unique collaboration has provided excellent opportunities to sample a high number of humpback whales early and late in the breeding season and across different age categories. The 2019 Hawaii sampling season is done for the year, and we will return to Maui from January to March 2020.”

“Like the whales, we are now shifting our focus back to the foraging grounds of southeast Alaska,” said Martin van Aswegen, a South African marine scientist in the UH Manoa Marine Mammal Research Program.

“I will be joining University of Alaska Fairbanks in early April for a two-week sampling trip, with the hope of measuring whales who have recently returned from the breeding grounds (or over-wintered in Alaska). Following our spring fieldwork, we will commence a five-month Alaska summer season in May.”

All research activities were conducted in accordance with NOAA permits 20311-01, 19703, 14585 and 19655. All UAV activities were conducted in accordance with FAA Part 107 regulations.

Through collaborations, the project aims to gain an understanding of intra-seasonal changes in body condition of humpback whales throughout the feeding and breeding seasons; inter-annual variability in body condition of humpback whales; and potential factors contributing to the decline in observed sighting rates of humpback whales in Hawaii and Alaska.