MMRP students present at the 2026 Hawaiʻi Conservation Conference

Last week, two MMRP students, Gussie Hollers and Cam Nemeth, presented at the Hawaiʻi Conservation Conference, sharing new work on the energetic needs of humpback whales on their Hawaiian breeding grounds. Both presentations tackled similar underlying questions from different angles: how much energy does it actually cost to be a humpback whale, and what could happen if something disrupts that budget?

This year's conference theme, Kē ewe ʻāina, asked us to think about the deep connections that link generations across time, a fitting frame for research on koholā, whose migration between Alaska and Hawaiʻi has been repeated across whale generations for far longer than we have been here to study it.

Theme: ʻImi i ke ʻEwe o ka ʻĀina — Guided by the Wisdom of ʻĀina, Medium: Digital Painting, Artist: Makaiwa Kanui, Year: 2026

Why energy matters

The Hawaiʻi population of humpback whales migrates roughly 6,000 miles each year between feeding grounds in Southeast Alaska and breeding grounds here in the islands. They spend the winter breeding, calving, and nursing without eating at all, living entirely off the fat reserves they built up over the previous summer.

Energy is a useful common currency for conservation because every threat a whale faces eventually shows up in the same energetic budget. A marine heatwave that reduces prey in Alaska and a boat that interrupts a resting mother in Hawaiʻi are very different threats, but both affect the whale's energy budget. Measuring that budget gives managers a way to weigh very different pressures on the same scale, and study their interactive effects.

Resting significantly reduces energy use for mothers and calves

PhD Candidate Gussie Hollers's presentation, Energetic benefits of resting behavior in humpback whale mother–calf pairs, focused on the energy budgets mothers and newborn calves. While in Hawaiʻi, mothers are fasting and nursing at the same time, so they need to spend as little energy as possible, while calves do the opposite, growing quickly and building muscle for the spring migration.

Using biologging tags and drone-based photogrammetry, her presentation showed that resting dives save a substantial amount of energy: roughly 45% less energy in mothers and 35% less in calves compared with active behaviors. That finding matters because mothers and calves rest in shallow coastal waters, where they are most exposed to boat traffic and noise.

Simulations based on published disturbance responses suggest that sustained daytime boat presence over about two months on the breeding grounds could cost a mother more than 150 kg of blubber, energy she cannot replace until she returns to Alaska months later. These are illustrative estimates rather than exact measured values, but they offer a framework for turning disturbance into real energetic currency, and a foundation for more detailed future work.

For her talk, Gussie received the Graduate Student Honorable Mention Oral Presentation award.

Locomotion is cheaper for larger whales

Incoming PhD student Cameron Nemeth presented Energetic Scaling of Locomotor Costs Across Body Sizes in Humpback Whales on Their Hawaiian Breeding Ground, asking how the cost of movement changes as whales grow.

Combining tag data and drone photogrammetry across 90,362 tailbeats from 62 whales ranging from small calves to full-grown adults, Cameron found that relative to their body size, larger individuals have lower transport costs. Specifically, he reported a 62% reduction in mass-specific propulsive costs between a 4 m calf and a 14 m adult. For a lactating female, propulsion accounts for about 21% of her daily energy expenditure while she is on the Hawaiian breeding grounds.

This work adds to the growing body of literature regarding the importance of large body sizes in baleen whales, and provides a novel approach to estimating the fine-scale energetic cost of various disturbances. For example, this model estimates locomotor costs of approximately 4.4 kJ/m in calves and 27.7 kJ/m in lactating females, illustrating how the same disturbance may impose substantially different energetic costs on members of a mother-calf pair. Together these results establish an energetic baseline for assessing how disturbance, habitat change, or shifting prey availability may affect different demographic groups in different ways.

What this means for whales in Hawaiʻi

Taken together, the two talks show that behavior affects energy budgets, so disturbance that changes movements or behavioral state carries a measurable cost. Resting is how a mother banks the energy her calf depends on, and movement is expensive especially for small calves. Rather than saying boat traffic is generally harmful, we can begin to estimate what a given level of it costs a mother in energy she cannot replace until she returns to Alaska. Future studies could use these results to refine management decisions: vessel approach distances, boat speeds in the shallow coastal waters where mother–calf pairs rest, and protection of the areas they use most.

Mahalo to our partners and funders

None of this work would be possible without our partners and funders. We are especially grateful to Dolphin Quest, whose long-standing support has funded the humpback whale fieldwork underpinning both of these studies, and who sponsored our attendance at this year's conference. Their commitment to marine mammal research and conservation directly enables the kind of long-term data collection that questions like these require.

Thanks also to UH Mānoa’s Hawai‘i Institute of Marine Biology, Pacific Whale Foundation, and Alaska Whale Foundation, for their invaluable assistance with tag data collection for this project. We would like to thank our corporate and philanthropic funders for making this research possible, includ- ing Our Oceans’ Netflix, Wildspace Productions, Freeborne Media, PacWhale Eco-Adventures and PWF donors, Young Brothers, the Omidyar Ohana Foundation, Brook Byers, Paul and Elle Stephens, Barbara and Duncan Chapman, Peter Beck, Benjy Garfinkle, Thomas Griggs, Thomas Tierney, Owen Williams, Deepak Srivastava, Bernard Alpert, Patricia Cahill, the Schwab Foundation, JP and Dalia Maheu, Denise O’Leary and Kent Thiry, Kristin and Larry Link and Brion Applegate.

Mahalo as well to our field volunteers, collaborators, and the permitting agencies whose work makes it possible to study these whales responsibly and with minimal disturbance. And finally, to the koholā themselves, as ʻaumākua and a manifestation of Kanaloa, for allowing us to learn from them.

If you’d like to support our research, please click the blue button below — any donation, big or small, makes a meaningful difference in helping us protect these incredible animals. Mahalo for being part of this work!