New publication: Are Hawaiʻi’s False Killer Whales Consuming Enough Food?
- jenscurrie4
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Written by: Jens Currie
We are pleased to share a new publication in Endangered Species Research, entitled: Body condition differs among social clusters and across years in endangered false killer whales in Hawaiʻi.
Authors: Jens J Currie, Brian Stirling, Grace Olson, Martin van Aswegen, Lewis Evans, Stephanie H Stack, Nozomi Kobayashi, Keiichi Ueda, Suguru Higa, William Gough, Fabien Vivier, Liah McPherson, Kyleigh Fertitta, Lars Bejder
The endangered false killer whales that live around the main Hawaiian Islands face an uncertain future. With an estimated population of only 139 individuals and a continued decline of 3–4% over the past decade, we are working to understand the factors that may be affecting their survival.
A new study conducted in collaboration between Pacific Whale Foundation and the Marine Mammal Research Program at the University of Hawaiʻi provides the first quantitative assessment of body condition in this population. Using drone-based photogrammetry collected over seven years, we measured the body size and volume of 64 whales, about half of the remaining population, allowing us to track changes in body condition in individual whales and across the population over time.
Body condition is one of the clearest indicators of whether an animal is finding enough food. When prey is abundant, whales maintain healthy energy reserves in the form of blubber and muscle and have a positive body condition. When prey becomes scarce, those reserves begin to decline, and so does the body condition. To ensure our measurements were as accurate as possible, we validated our approach using 3D scans of false killer whales, allowing us to reconstruct body shape in high detail and refine our estimates of volume and mass. This step provides confidence that the changes we detect reflect real biological shifts, not measurement error.
The study found that body condition varied among social clusters and across years, with the lowest average condition occurring in 2020 following a period of unusually warm ocean temperatures associated with a marine heatwave. Individual whales also showed dramatic changes in condition over time.
In some cases, whales lost nearly a quarter of their body weight, around 400 pounds, in just a few months.
These findings suggest that some individuals may experience periods of nutritional stress, potentially linked to changes in prey availability. False killer whales in Hawaiʻi rely heavily on large pelagic fish such as tuna, mahi-mahi, and wahoo, species that are also targeted by commercial fisheries. While the study does not directly measure food intake, it provides an important first step in understanding the health of this endangered population and the pressures it may be facing in Hawaiʻi’s marine ecosystem.
The next phase of this collaborative effort will focus on estimating the energetic needs of the population. By determining how much food the remaining whales require, we hope to better understand how ecosystem changes and fisheries interactions may influence the recovery of this species.
Ultimately, protecting Hawaiʻi’s false killer whales requires understanding not only the trends and threats they face, but whether the ocean can continue to provide the food they need to survive.
Currie JJ, Stirling B, Olson G, van Aswegen M, Evans L, Stack SH, Kobayashi N, Ueda K, Higa S, Gough W, Vivier F, McPherson L, Fertitta K, Bejder L (2026) Body condition differs among social clusters and across years in endangered false killer whales in Hawai'i. Endang Species Res 60:esr01505. https://doi.org/10.3354/esr01505
If you’d like to contact the lead author with questions, feel free to reach out to Jens at curriej@hawaii.edu.
Images and videos collected under ESA NMFS Research Permit # 21321/27099.
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