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Whale foundation joins research of humpback sighting drop-off

The Maui News

The Pacific Whale Foundation is collaborating with the UH-Manoa Marine Mammal Research Program on a study focusing on the reasons for the decline in humpback whale sightings.

Since the delisting of the Hawaii humpback whale population from the Endangered Species List in 2016, the sighting rates of humpbacks in the state and southeast Alaska have dropped, the Pacific Whale Foundation said earlier this week.

“There is currently a lack of understanding of why humpback whale sighting rates have reduced,” the whale foundation said in its news release. “This project will contribute to efforts investigating the possible causes of this recent trend.”

The focus of the study will be on changes in body condition and animal health and particularly on quantifying the bioenergetic demands of humpbacks migrating between Alaskan foraging grounds and Hawaiian breeding grounds, the whale foundation said.

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

Joining the whale foundation in assisting the UH-Manoa Marine Mammal Research Program are University of Hawaii-Hilo, University of Alaska Fairbanks and the Alaska Whale Foundation. The Pacific Whale Foundation’s role includes sharing its photo identification catalog that dates back to 1981, assisting with field sampling efforts and developing long-term datasets and analysis.

In January, Ultimate Whale Watch on Maui hosted researchers for 10 days on its vessel. The researchers completed 243 drone flights within the Hawaiian Islands Humpback Whale National Marine Sanctuary over 17 days with 150 humpback whales measured per month. This included adults and sub-adults as well as single individuals, mother-calf-escort groups and competitive male groups, the whale foundation said.

Dr. Adam Pack, a UH-Hilo professor, joined the whale foundation and UH-Manoa teams for tissue sampling using drone measurements, biopsy samples and photo-identification to study humpbacks body condition, steroid hormones, lipid content and stable isotopes, the whale foundation reported. Over a three-day period, the team managed to biopsy sample about 20 humpbacks.

The research in Hawaiian waters has ended for the season with the focus shifting to foraging grounds of southeast Alaska, said UH researchers. The team will return to Maui from January to March next year.