Some of �Ჹ�ɲ���ʻ��’s endangered false killer whales are rapidly losing weight, a warning sign that warming oceans and limited prey may be pushing one of the nation’s smallest whale populations closer to extinction, according to research by a team including scientists from the University of Hawaiʻi at Mānoa.

The findings provide the first quantitative evidence that nutritional stress and competition with fisheries may be accelerating the decline of this iconic population, which now numbers fewer than 140 individuals.

The research—a partnership between the (PWF), (MMRP) at ����Vlog�ٷ� Mānoa and —utilized high-resolution drone photogrammetry to track 68 whales (roughly half the remaining population) between 2019 and 2025.

Rapid declines and climate links

The study documented extreme physiological shifts, including one individual that lost an estimated 28% of its body mass—approximately 500 pounds—over a 10-week period. Researchers also found that the population’s overall Body Condition Index hit a record low in 2020. This decline coincided with a severe marine heatwave and the largest single-year population drop in recent history, suggesting that rising ocean temperatures could be impacting the whales’ ability to maintain necessary energy reserves.

“This study is a critical step in understanding whether prey limitation is driving the extinction risk for these whales,” explains Jens Currie, Chief Scientist at PWF, PhD candidate in the , and lead author of the study. “Our findings suggest that many individuals are living on a thin metabolic margin. We are now examining how competition with fisheries for high-energy prey like ‘ahi (yellowfin tuna) and mahimahi may be forcing these whales into a state of chronic nutritional stress.”

Mapping health across the archipelago

The research highlights that health is not distributed equally across the population. Whales in “Cluster 1,” known for traveling broad distances across the islands, showed significant variability in their physical condition. This suggests that the high energetic cost of moving long distances to find prey may be taking a heavier physical toll on certain social groups than others.

To ensure the highest level of accuracy, the research team validated their drone measurements against 3D scans of whales in human care at the Okinawa Churashima Foundation in Japan. This calibration provided the foundational data needed to convert aerial images into precise weight and volume estimates, confirming that the study’s measurements are accurate to within 3%.

“This level of precision allows us to pinpoint exactly when and where these whales are struggling, which is key for directing conservation efforts,” said Lars Bejder, MMRP director, title=”Hawaiʻi Institute of Marine Biology”>HIMB professor, and co-author of the study.

The whales found in Hawaiʻi are a distinct, island-resident population adapted to the region’s coastal ecosystems and dependent on these waters for survival. They represent one of the smallest and most endangered whale populations in the United States, where the loss of even a few animals can have consequences for the entire population.

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A breakthrough in marine mammal health surveillance can now detect deadly diseases in whales and dolphins in oceans, beaches and remote locations, thanks to new research from the University of Hawaiʻi at Mānoa.

The ����Vlog�ٷ� Health and Stranding Lab at the (CTAHR) worked together with international researchers to validate a portable, field-deployable molecular diagnostic tool for Cetacean Morbillivirus (CeMV). The study was published in .

Rapid detection in the field

CeMV has caused mass deaths of thousands of marine animals globally. Traditionally, detecting such pathogens required sending samples to specialized laboratories, often resulting in delays of weeks to months.

“This is the first application of a field-deployable system for rapid testing for whales and dolphins,” said Kristi West, director of the ����Vlog�ٷ� Health and Stranding Lab. “It breaks down barriers to detection because it can be used remotely, even without a traditional lab nearby.”

The portable unit delivers results in about an hour, aiding decision-making during mass stranding events. It is designed for hot, humid environments, making it essential for detecting outbreaks early and potentially preventing larger epidemics. The system uses high-speed testing to provide rapid, on-site results. It proved effective across multiple divergent strains from Hawaiʻi, Europe and Brazil, even in archived tissues up to 28 years old.

“We want to train others so we can increase what we know about disease in many other areas of the world,” West said.

Global collaboration and training

To ensure this technology reaches those who need it most, ����Vlog�ٷ� researchers hosted a workshop in Honolulu with Professor Wei-Cheng Yang from National Taiwan University’s Veterinary School to train stranding responders and scientists from across the Pacific.

Participants included staff from the Taiwanese Cetacean Society, and representatives from the Hawaiʻi Department of Land and Natural Resource’s Division of Aquatic Resources, NOAA Fisheries, the U.S. Geological Survey’s National Wildlife Health Center, biologists from Guam and Saipan and CTAHR graduate students.

During the workshop, researchers ran tests on known positive and negative samples for diseases impacting dolphins and Nene, the endemic Hawaiian goose. The Taiwanese team also shared their insights from a mass stranding of 11 pygmy killer whales they had responded to just days before arriving in Hawaiʻi, which resulted in the successful release of seven whales.

The project is supported by U.S. Pacific Fleet Environmental Readiness Division and a joint zoonotic disease grant with the state of �Ჹ�ɲ���ʻ��’s Department of Land and Natural Resources and involves collaborators from Taiwan, the Philippines, Spain, and Brazil.

From land–borne pathogens to high–speed vessel strikes, Pacific whales and dolphins are caught in a “perfect storm” where human-caused trauma and infectious diseases were found in more than 65% of investigated strandings.

by University of Hawaiʻi at Mānoa researchers provides insights into the threats whales and dolphins face in the Pacific Islands.

Based on 272 stranding investigations of 20 cetacean species between 2006 and 2024, the study provides foundational data to better manage and conserve Hawaiʻi’s whales and dolphins.

“Dolphins and whales are sentinels of ocean health—we need to understand why these animals die to help others live,” said Kristi West, director of the ����Vlog�ٷ� Health and Stranding Lab at the .

Disease is prevalent

Over 18 years, scientists examined more than three-quarters of the stranded whales and dolphins to understand why they died. Most cases (62%) were linked to diseases, and about half of those animals were in poor body condition due to long-term illness.

Infectious agents proved to be a significant threat, affecting 11 different species, including striped dolphins and Longman’s beaked whales. Two of the most concerning pathogens were morbillivirus and brucella, which can cause serious brain and lung problems in marine mammals.

Toxoplasmosis—a parasite that infects warm-blooded animals and spreads through cat feces across the environment—was responsible for the deaths of two spinner dolphins and one bottlenose dolphin.

Trauma linked to humans

The study revealed that 29% of all strandings were linked to anthropogenic (human-caused) trauma. Vessel strikes were a significant risk, resulting in fatal vertebral and skull fractures for seven individuals, including two pygmy sperm whales, two humpback whale calves, a goose-beaked whale, a spinner dolphin and a striped dolphin.

Interactions with marine debris and fisheries were confirmed as fatal in multiple cases, including:

• A sperm whale died from plastic and fishery debris blocking its stomach.
• A bottlenose dolphin died after a fishhook tore into it.

Public reporting urged

In the Pacific Islands, most dolphins and whales die at sea, and recovery rates are very low. Each stranding examination provides stakeholders with valuable information about what is happening to these animals and their ecosystem. Public reporting is critical to understanding threats to marine mammal health.

Sightings of dead or distressed marine mammals can be reported to the statewide NOAA Marine Wildlife Hotline at (888) 256-9840, toll-free.

For the first time, scientists have calculated a detailed “energetic budget” for Hawaiʻi‘s short-finned pilot whales, revealing what it takes to power their extreme, 800-meter (2,600-feet) dives for food.

A new study led by the University of Hawaiʻi at Mānoa’s (HIMB) found an average adult whale must eat 142 squid daily to survive, scaling up to 416 million squid annually for the entire population of short-finned pilot whales. This data, published in the , provides a new benchmark for protecting the historically understudied marine mammals.

“Pilot whales are one of the only oceanic dolphins that regularly dive to extreme depths—up to 1,000 meters—to find prey,” said William Gough, (MMRP) postdoctoral researcher and lead author of the study. “This deep-diving, high-risk foraging strategy requires a delicate balance between the energy they spend and the energy they acquire. Our study is the first step in quantifying that balance for this specific population.”

Understanding precisely how much energy the animals require is essential for understanding how to effectively manage against threats and ensure their survival.

“This detailed scientific data gives Hawaiʻi management agencies a critical tool to monitor how changes in the ocean—from warming waters to ship noise—might push the pilot whales past their survival limit,” said Lars Bejder, MMRP director and co-author of the study.

The deep waters surrounding the Hawaiian Islands are home to a genetically distinct population of short-finned pilot whales. These highly social, toothed whales are not migratory; they remain with their tight-knit, multi-generational families in one region for life. The population forages year-round where they pursue their preferred prey: squid.

Requirements can inform effective management

“Deep-diving species like pilot whales are especially vulnerable to human-induced disturbances, such as noises from ships or changes in ocean temperature, which can disrupt foraging or increase their energetic costs,” said Gough. “If they use more energy than they can find, they face an energy crisis that weakens their health, hurts their ability to fight off disease, and ultimately limits their ability to reproduce and recover the population.”

Despite this inherent vulnerability, the Hawaiian pilot whale population benefits from a stable and abundant squid food source, which may better equip them to cope with environmental disturbances than populations elsewhere.

The team placed advanced Customized Animal Tracking Solutions (CATS) tags on eight short-finned pilot whales off the coast of Lānaʻi between 2021 and 2024. The tags recorded movement, depth and sound, and used 2K cameras with LED headlights to observe the whales in their lightless, 800-meter-deep hunting habitat. The researchers developed a new method to estimate minute changes in energy usage by combining data from tags with body measurements from aerial drone footage.

“Getting to be on the water and close to these animals is an absolute joy,” said Gough. “But the fact that we can see into their world, even at 800 meters and under extreme pressures [80 times that at the surface], and observe them capturing their food in complete darkness, feels unbelievable to me. It’s truly a privilege to document the lives of these elusive, deep-diving whales.”

A new study by researchers from the University of Hawaiʻi at Mānoa’s (HIMB) has revealed that endangered Hawaiian monk seals have a hidden vocal repertoire, using a complex range of sounds to call underwater.

Previously, scientists believed monk seals had a simple repertoire, identifying only six different calls based on seals in human care. In this study, the scientists analyzed thousands of hours of passive acoustic data from the wild, they discovered 25 distinct vocalizations.

The study, published in , also found that these low–frequency calls are produced by the seals throughout the day. These vocal types were heard consistently across the Hawaiian archipelago, with calling rates highest at sites where more seals were present. This new understanding of the monk seals (Neomonachus schauinslandi) vocal repertoire opens up a new window into their acoustic behavior.

“We discovered that Hawaiian monk seals—one of the world’s most endangered marine mammals—are far more vocal underwater than previously known,” said Kirby Parnell, lead author of the study and a PhD candidate with (MMRP). “By analyzing over 4,500 hours of recordings from across the Hawaiian Archipelago, we identified more than 23,000 vocalizations representing at least 25 distinct call types.”

Monk seal vocalizations

The study, which deployed passive acoustic recorders at five key monk seal habitats from Molokaʻi to the Northwestern Hawaiian Islands, uncovered:

Expanded vocal repertoire: Researchers identified 20 previously undocumented calls.

Novel communication strategy: The research provides evidence that monk seals can combine different vocalizations together, creating “combinational calls”—a communication strategy never before reported in any pinniped (seals, sea lions and walruses) species.

A foraging call: The team discovered one novel elemental call type “the whine” produced during foraging, representing only the second known example of a seal species using vocalizations while pursuing prey.

“We were surprised by the sheer diversity and complexity of monk seal vocalizations,” said Parnell. “The discovery of combinational calls, where seals link multiple call types together, suggests a previously unknown level of complexity in pinniped acoustic communication. Finding a new call type—the Whine—associated with foraging behavior was also unexpected and suggests that monk seals may use sound not only for mating or socializing, but possibly for foraging purposes as well.”

Seal conservation in Hawaiʻi

These results lay the foundation for using passive acoustics to monitor monk seal populations to protect their acoustic habitats as human activity persists in Hawaiian waters. Future research will decisively link these documented vocalizations to specific Hawaiian monk seal behaviors, such as foraging, swimming, social interactions and reproduction. Next steps involve developing automated detection systems to monitor the seals’ acoustic activity more efficiently and non–invasively.

“This research provides the first comprehensive description of free–ranging Hawaiian monk seal underwater sound production, an important step toward understanding how they use sound for critical life–history events,” said Lars Bejder, director of MMRP, professor at HIMB and co–author of the study. “Because their vocalizations overlap with the same low–frequency range as many human–generated sounds (e.g. vessel noise), this work lays the foundations to evaluate how ocean noise may affect communication, reproduction, and behavior in this endangered species.”

About the team

The team included undergraduate and graduate students, and recent ����Vlog�ٷ� alumni, and coauthors from France and the .

“Manually annotating over 23,000 calls by hand is no small feat, and I have a team of interns to thank for helping with the analysis!” said Parnell. “This research would also not have been possible without the support of the Hawaiian Monk Seal Research Program, who deployed and retrieved the acoustic recorders in the .”

The work was supported by NOAA Fisheries via the Cooperative Ecosystem Studies Unit (CESU) award NA19NMF4720181.

The energy required for newborn humpback calves to grow after birth is 38 times greater than what they needed inside the womb according to research from University of Hawaiʻi at Mānoa (HIMB) in collaboration with Alaska Whale Foundation and other key partners. These findings were published in .

“This study addresses a key piece of the energetic puzzle in estimating the cost of being a humpback whale in the North Pacific: the cost of growth,” said Martin Van Aswegen, lead author of the study and postdoctoral researcher at HIMB’s (MMRP). “While previous research has shown that these whales must grow very large in a short period of time, the actual energetic expense of that accelerated growth remained unknown.”

Geared to grow

Research revealed that calves require 6–8 times the daily growth energy of an adult whale, and they achieve 30% of their total lifetime growth in less than their first year of life. In fact, more than 60% of a calf’s crucial energy needs for growth occur within the first 150 days of birth.

Humpback mothers must support lactation while fasting in Hawaiʻi breeding grounds and then traversing back to their feeding grounds in Alaska. This exposes the mother-calf pair to significant vulnerability when ocean conditions threaten the mother’s energy stores.

The study found that a mother’s ability to produce a large, healthy calf—one more resilient to starvation and environmental stress—hinges directly on her own energy reserves. Smaller females, with lower energy reserves, face trade-offs that constrain how often they can reproduce and how much they can invest in their offspring.

“By quantifying the energetic demands of growing big and strong, we provide crucial insight into how external pressures, including climate change and human disturbance, may affect the survival and resilience of these ocean giants,” said van Aswegen.

Warning signs

The study also revealed a worrying trend: mature humpback whales today are noticeably shorter than historical records, indicating a decline in body size of approximately 1–2 feet since the mid-1900s. Recent signs of humpback population stress in the region include a 76.5% drop in mother-calf sightings and an estimated 80% drop in crude birth rates in Hawaiʻi between 2013–2018. These declines coincided with the longest-lasting global marine heatwave, suggesting that low food availability prevented mothers from getting enough energy for the demands of nursing and calf growth. The results affected calves and juveniles, whose higher energy requirements make them highly vulnerable.

“If humpback whales are to survive threats like extreme marine heatwaves and other stressors that result from human activity, we need to understand precisely how reproductive females accumulate and allocate energy to support the exponential costs of gestation and lactation,” said Lars Bejder, director of MMRP, professor at HIMB, and senior author of the study. “This knowledge is the foundation for making the urgent conservation changes required for the population’s future.”

Drones, data

The team used drones to take high-resolution aerial photos of more than 1,500 humpback whales in Hawaiʻi and Southeast Alaska. They combined drone measurements with historical records and biological samples to acquire a full picture of humpback energetic needs throughout their lifespan.

“This non-invasive approach gives us a rare look at whale biology as they live, instead of relying only on historical whaling data from the 1900s,” said van Aswegen. “Our humpback whale health database, comprising over 12,000 measurements of 8,500 individual whales in the North Pacific, is being used across several projects within the Marine Mammal Research Program and abroad.”

The data can be used in conjunction with fine-scale behavior and movement data (from biologging tags), reproductive and stress hormone data (from tissue and breath samples), and tissue data derived from post-mortem events.

Partnerships

This work was made possible through MMRP, HIMB, Alaska Whale Foundation, Pacific Whale Foundation, University of Alaska Southeast, Glacier Bay National Park and Preserve, University of Alaska Fairbanks, Oregon State University, The Dolphin Institute (����Vlog�ٷ� Hilo), ����Vlog�ٷ� Health and Stranding Lab, and HappyWhale. Hawaiʻi fieldwork was funded through ����Vlog�ٷ� Mānoa, the US Department of Defense’s Defense University Research Instrumentation Program, the Office of Naval Research, ‘Our Oceans,’ Netflix, Wildspace Productions and Freeborne Media, the Omidyar Ohana Foundation, the National Marine Sanctuary Foundation, and PacWhale Eco-Adventures, as well as members and donors of Pacific Whale Foundation. Southeast Alaska research was funded through awards from the National Geographic Society, the Lindblad Expeditions-National Geographic Funds, and the North Pacific Research Board.

In a surprising discovery, a reveals that among seven species of baleen whales, only the humpback is capable of the high-performance turns required for its signature bubble-net feeding strategy. The research, led by recent graduate Cameron Nemeth, shows humpbacks use their unique pectoral flippers to achieve this maneuver, shedding new light on the biomechanics of this iconic feeding strategy.

Nemeth just earned his bachelor of science degree in marine biology, and conducted this research as part of a larger project at ����Vlog�ٷ� Mānoa Hawaiʻi Institute of Marine Biology (HIMB) . The study focuses on solitary bubble-net feeding, a complex foraging strategy where whales release bubbles in a ring to corral prey. By combining data from drones and non-invasive suction-cup tags, Nemeth and his team were able to accurately quantify the turning performance required for this maneuver.

“The fact that humpback whales’ pectoral flippers enhance their maneuverability wasn’t the most surprising part of our study, as there have been previous studies on the morphology of these flippers,” said Nemeth. “However, it was shocking to discover that amongst thousands of turns from a variety of behavioral states, no other species of whale examined were achieving the turning performance required to create a bubble-net.”

Highly efficient pectoral flippers

The research indicates that the humpback whale’s large pectoral flippers can generate nearly half of the force needed to turn, making them highly efficient at this feeding strategy. Other whale species, even if physically capable of similar turns, would need to expend significantly more energy, likely making the strategy energetically impractical. Humpbacks’ special body shape allows them to successfully hunt smaller or scattered groups of prey.

“This is a great example of a collaborative research project that took advantage of datasets from 28 different research organizations across six countries,” said Lars Bejder, research professor at HIMB, principle investigator of MMRP, and co-author of the study. “These sorts of initiatives are able to address questions that otherwise would be very difficult to answer.”

This research is significant for Hawaiʻi, as humpback whales fast while in the islands, relying on the energy reserves they build up on Alaskan feeding grounds. Understanding the efficiency of their foraging techniques is crucial for assessing their overall health and energetic needs, which ultimately impacts their stay in Hawaiian waters.

Ongoing research, new Hawaiian language precedent

Nemeth led this large-scale project during his final semester as an undergraduate student at ����Vlog�ٷ� Mānoa. He will be continuing his research with the MMRP, transitioning to a PhD program in fall 2026 to lead the lab’s ongoing humpback whale project in Maui.

In a move to increase the availability of scientific literature in the Hawaiian language, Nemeth also worked with the journal to include a Hawaiian-language abstract for the paper. He translated the abstract himself and worked with a Hawaiian language professor to edit the text, setting a precedent for future publications from the lab.

Funding for this study was provided by ����Vlog�ٷ� Mānoa, the Omidyar Ohana Foundation, and the Lindblad Expedition–National Geographic Fund. Equipment was provided through a Defense University Research Instrumentation award from the U.S. Department of Defense.

Breathtaking footage of humpback whales is part of a new 12-minute video released in partnership between the (MMRP) at the University of Hawaiʻi at Mānoa and , in celebration of World Ocean Day (June 8). “In the Wake of Whales” follows ����Vlog�ٷ� scientists as they study and monitor the annual migration of humpback whales from Alaska to Hawaiʻi.

The video offers fascinating insights into one of nature’s most remarkable journeys—when thousands of whales travel nearly 3,000 miles to Hawaiʻi each year to give birth. Among the many facts shared: pregnant females do not eat during the journey, relying entirely on their fat reserves; and a single pregnancy costs a mother about 22 million calories, including 97 pounds of fetal growth per day in the final months.

“Understanding the biology and behavior of humpback whales is essential, especially now as changing ocean conditions threatens their habitats and migratory patterns,” said MMRP Director Lars Bejder. “This video helps explain how their endurance and sacrifices are truly extraordinary.”

Whale tails, whale tales

The video features researchers documenting whale behaviors, collecting data and photographing the flukes of individual whales. These unique tail markings act as IDs and are uploaded to Happy Whale, a global database available to scientists and the public. With more than 10,000 whales cataloged—representing about 80% of the estimated 12,000 whales that migrate to Hawaiʻi—MMRP’s collection is the largest in the world.

“Dolphin Quest is honored to support this research and help share it with the public,” said Dolphin Quest Co-Founder Rae Stone. “This project combines the best of science, education and conservation—and makes it accessible for everyone.”

MMRP operates from the on Moku o Loʻe in ����Ա�ʻ�dz�� Bay and has been focused on humpback whale research for the past five years, in strategic collaboration with the . This work has helped illuminate how changing ocean conditions and increased marine heatwaves may be affecting whale health, reproduction and migration.

Dolphin Quest, founded in 1988, has locations on Oʻahu, Hawaiʻi and Bermuda. Its mission is “to protect marine animals and their environments through experiential learning and scientific discovery.” .

The video aims to inspire and educate viewers of all ages on the importance of protecting humpback whales. At the end of the film, a QR code invites viewers to support ongoing research and conservation efforts. .

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University of Hawaiʻi at Mānoa biologists used drone imagery to understand how nursing humpback whale mothers and their calves fare as they cross the Pacific Ocean. Recent declines in North Pacific humpback whale reproduction and survival of calves highlight the need to understand how mother-calf pairs expend energy across their migratory cycle. The study was .

The team used drone cameras to measure calf growth and maternal body condition days after calf birth in Hawaiʻi, and then compared these measurements to the body conditions of humpback females in Alaska feeding grounds, measuring pregnant and lactating (producing milk for nursing) females as well as humpback females whose reproductive status was unknown.

“A total of 2,410 measurements were taken from 1,659 individuals, with 405 repeat measurements from 137 lactating females used to track changes in maternal body volume over migration,” said Martin van Aswegen, (MMRP) PhD candidate and lead author of the study.

Size matters

The research shows that larger females produced larger, faster-growing calves. Over a 6-month period, lactating females decreased in body volume by an average of about 17%, whereas the calves’ body volume increased by nearly 395% and their length increased by almost 60%. In Hawaiʻi, humpback whale mothers lose nearly 214 pounds of blubber per day. Over a 60-day period, this is equivalent to losing roughly 50 tons of krill. Mother humpbacks in Hawaiʻi lost 20% of their body volume over 60 days of lactation, and the energy they used lactating surpassed the total energetic cost of their year-long pregnancies.

In Southeast Alaskan feeding grounds, lactating humpback mothers were found to have the slowest rates of weight gain compared to non-lactating females, gaining about 32 pounds each day. Comparatively, pregnant and nonpregnant females gained weight at six and two times the rate of the lactating females, respectively.

“The surprising part of this study was our ability to find the same individual mothers and calves over great distances and time periods,” said van Aswegen. “To measure the same whales over 3,000 miles apart over a period of roughly 200 days is truly remarkable and provides such valuable data for the questions we were asking.”

Birth rates decline

Studies document a 76.5% decline in mother-calf encounter rates in Hawaiʻi between 2013 and 2018, with birth rates declining by 80% from 2015 to 2016. In Southeast Alaskan feeding grounds, research reveals total reproductive failure in 2018, with calf survival decreasing tenfold from 2014 to 2019. These observations coincided with the longest lasting global marine heatwave, which shifted food webs and reduced availability of prey throughout the North Pacific. It is believed that humpback whales were unable to acquire sufficient food, resulting in nutritional stress and declines in reproduction.

“This work forms the basis for future studies investigating the energetic demands on humpback whales,” said Lars Bejder, MMRP director and co-author of the study. “Our humpback whale health database, comprising 11,000 measurements of 8,500 individual whales in the North Pacific, is being used across several projects within the Marine Mammal Research Program and abroad. These studies will be used to better predict the resilience of large baleen whale species in the face of threats, including disturbance, entanglement, vessel collision, and climate change.”

“This study showcases how teamwork across disciplines and institutions helps us uncover the intricate relationships between maternal health, calf growth, and environmental stressors,” said Jens Currie, MMRP PhD candidate, chief scientist at Pacific Whale Foundation and co-author of the study.

This work was done in partnership with , and other partners.

Proper intake of food is essential for pregnant humpback whales to pull off the extreme physical feat of annual migration between Hawaiʻi and Alaska. Researchers at the (MMRP) at University of Hawaiʻi at Mānoa (HIMB) revealed the energetic cost and vulnerabilities of migratory humpback mothers-to-be in a study .

Humpbacks feed in polar waters and then must fast and migrate up to 5,000 km to the tropical waters where they breed and give birth. Humpback whale mothers spend about 10 months in pregnancy, averaging about 100 days a trimester. Using a variety of new and historical records of measurement on the whales they were able to determine their findings. They found that the size of mothers directly correlated to the size of the fetus—the larger the mother the larger the fetus and the larger the growth rate.

The team determined that the energy cost of the first two thirds of the pregnancy were negligible, comprising .01–1.08% of the energy used. The majority of the energy needs came in the final third of the pregnancy, when requirements ticked up to 98.2%.

Crucial 100 days of pregnancy

“It was surprising to see how the peak of energy requirements coincided with the onset of fasting in pregnant females, ultimately highlighting how crucial those final 100 days of pregnancy are for this migratory species,” said Martin van Aswegen, PhD candidate and lead author of the study. “Females that are late in the pregnancy are therefore particularly vulnerable to disruptions in energy balance, given periods of greatest energetic stress coincide with fasting and migration to sub-tropical breeding grounds. Our study highlights a particularly vulnerable period for pregnant humpback whales. This is important, because once these whales leave their high-latitude feeding grounds, they have a finite amount of energy available to invest in their offspring over a 3–5 month fasting period, with energy requirements being even higher after calf birth.”

A 75.6% decline in the number of humpback whale mothers with calves was seen and off Hawaiʻi between 2013 and 2018. In Southeast Alaska, shows calf production was approximately six times lower between 2015 and 2019 compared to pre-2015 years, with mid-summer calf mortality increasing tenfold from 2014 to 2019. Studies have reported significant and prolonged shifts in the distribution of the marine food web, resulting in poor feeding conditions for humpback whales.

“This research underpins future studies on humpback whale energy demands,” said Lars Bejder, co-author of the study and director of MMRP. “Our drone-collected whale health database, developed in partnership with the Alaska Whale Foundation, includes over 11,000 measurements from 8,500 individual North Pacific whales. Its extensive temporal and spatial scale offers invaluable insights into the effects of large-scale climatic events on this iconic sentinel species. Sustaining such long-term, wide-scale studies is crucial for understanding these impacts within the context of natural variability in whale health.”

“This research underscores the value of collaboration in tackling complex questions about the lives of humpback whales,” said Jens Currie, co-author and chief scientist at Pacific Whale Foundation. “Through large-scale collaborations, we’re able to gain critical insights into the challenges migratory whales face during pregnancy to better inform conservation strategies. Together, we can address large-scale ecological challenges that no single institution could achieve alone.”

The research was done in partnership with , and others, and highlights key factors that will help inform future conservation.

Indigenous science, coastal resilience and marine mammals were a few of the key topics covered in a visit to the University of Hawaiʻi at Mānoa’s (HIMB) from members of the Ocean Research Advisory Panel (ORAP) on September 3. ORAP spent time with HIMB researchers and explored the Heʻeia National Estuarine Research Reserve (NERR) to better understand current research on the state of our oceans.

ORAP’s 18 members represent the fields of marine science, technology and policy, and hold the important task of making recommendations to the White House’s Ocean Policy Committee. The visit to Hawaiʻi was intended to not only inform what such a national strategy should look like, but to also acquire ideas about which areas of policy the group should focus on in the cohort’s second year.

The team of advisors explored topics including Indigenous science and technology through a Native Hawaiian lens; the latest approaches to coral restoration and resilience; the changing state of Hawaiʻi fisheries; breakthroughs in shark conservation; whales and dolphins as sentinels of our changing ocean; and biocultural practices strategies for coastal resilience.

“It was an honor to host ORAP,” said Megan Donahue, interim director of HIMB. “We shared how HIMB research informs the challenges and opportunities for ocean conservation in biocultural restoration of our coastal communities, strategies for reef resilience and coastal protection, and understanding how a diversity of marine organisms are responding and adapting to our changing oceans.”

Restoration efforts, co-stewardship

The team visited Paepae o Heʻeia, where ORAP toured the restoration efforts of the 800-year-old Hawaiian fish pond and learned about the benefits of Indigenous aquaculture systems. The panel observed research underway at NERR, which is one of the nation’s leading models of co-stewardship, including collaborative research between a university and an Indigenous community.

“The Biden Administration has issued executive memos and federal guidance about including Indigenous Knowledge in research, policy, and decision making, but many in the policy sphere still don’t know what that can look like,” said HIMB Assistant Professor and ORAP member Kawika Winter, who is director of Heʻeia NERR. “By bringing the Ocean Research Advisory Panel here, they are able to witness, experience, and learn first-hand what it can look like to effectively weave Indigenous Knowledge and university research.”

ORAP focused the first of its two-year term on advising the Ocean Policy Committee regarding the development of a National Ocean Data Strategy that improves data management, grows partnerships, and advances access and usability.

Using drones to successfully assess the age of critically endangered, free-ranging dolphins in Greece is the focus of new research at the University of Hawaiʻi at Mānoa (HIMB). This work, done in partnership with the Tethys Research Institute, informs researchers’ understanding of population abundance and demographics, which can improve management practices and help ensure their survival. The study was .

(MMRP) researchers are comparing the drone imagery results with long-term data and data from stable, non-endangered bottlenose dolphin populations in Shark Bay, Australia, and Sarasota Bay, Florida.

“In [our new] study, we highlight the speed and accuracy of UAS-photogrammetry (drone imagery) in assessing the age structure of free-ranging dolphin populations, and the implications towards management and conservation,” said Fabien Vivier, MMRP researcher and lead author of the study. “Our hope is that by using this method, we can quickly monitor the age-structure of free-ranging dolphin populations. This information can facilitate the detection of early signs of population changes, such as a decrease in the number of calves, and provide important insights for timely management decisions.”

Healthy dolphin populations have a consistent proportion of calves, juveniles and adults; a deviation from this can suggest the population is unstable. Using drones, researchers were able to quickly quantify the age-structure of the critically endangered dolphin population in Greece in a few days.

Previous study classifies dolphin age

In a previous study, the MMRP team used specialized calibrated drones to successfully measure the length of free-swimming dolphins and classify them by age.

“When dolphins come to the surface to breathe, they expose their blowhole and dorsal fin,” said Vivier. “By measuring the distance between the two, we can estimate their total body length. Since total length is related to age, we can estimate the age-group of a single dolphin.”

Aquatic mammals known as cetaceans, which include whales, dolphins and porpoises, face a slough of threats from habitat degradation, climate change, fisheries, and chemical and noise pollution. One quarter of the 92 known cetacean species are at risk of extinction, and there is a clear and urgent need to implement effective conservation strategies.

The project was done in collaboration with the Shark Bay Dolphin Research Project and the Sarasota Dolphin Research Program. The work in Greece was funded by the Office of Naval Research (ONR), OceanCare and the Costas M Lemos Foundation. The work in Hawaiʻi is funded by ONR, NOAA Pacific Islands Fisheries Science Center, the Omidyar ʻOhana Fund at Hawaiʻi Community Foundation and Dolphin Quest.

Discovering a behavior key to humpback whales’ survival and offering a case to include humpbacks among the rare animals that make and wield their own tools is the focus of new research out of the University of Hawaiʻi at Mānoa. researchers have known that humpback whales create “bubble nets” to hunt, but they discovered that they manipulate the bubble net to maximize their food intake in Alaskan feeding grounds.

The research, done in partnership with (AWF), was published in .

“Many animals use tools to help them find food, but very few actually create or modify these tools themselves,” said Lars Bejder, co-lead author of the study and (MMRP) director. “We discovered that solitary humpback whales in southeast Alaska craft complex bubble nets to catch krill, which are tiny shrimp-like creatures. These whales skillfully blow bubbles in patterns that form nets with internal rings, actively controlling details like the number of rings, the size and depth of the net, and the spacing between bubbles. This method lets them capture up to seven times more prey in a single feeding dive without using extra energy.”

Success in hunting is key for the whales’ survival. Humpback whales’ energy budget for the entire year depends on their ability to capture enough food during summer and fall in Alaska. Unraveling the nuances of their carefully honed hunting technique sheds light on how migratory humpback whales consume enough calories to traverse the Pacific Ocean.

Demystifying whale behavior

Marine mammals known as cetaceans include whales, dolphins and porpoises are difficult to study. For this study researchers employed specialty tags and drones to study the whales’ movements from above and below the water.

“We deployed non-invasive suction-cup tags on whales and flew drones over solitary bubble-netting humpback whales in Alaska, collecting data on their underwater movements,” said William Gough, co-author and MMRP researcher. “The tools have incredible capability, but honing them takes practice. Whales are a difficult group to study, requiring skill and precision to successfully tag and/or drone them.”

Improved management to come

Cetaceans throughout the globe face a slough of threats that range from habitat degradation, climate change, fisheries, to chemical and noise pollution. One quarter of the 92 known cetacean species are at risk of extinction, and there is a clear and urgent need to implement effective conservation strategies on their behalf. Understanding this essential behavior makes resource managers better poised to adeptly monitor and conserve the feeding grounds that are critical to their survival.

“This is a rich dataset that will allow us to learn even more about the physics and energetics of solitary bubble-netting,” said Bejder. “There is also data coming in from humpback whales performing other feeding behaviors, such as cooperative bubble-netting, surface feeding, and deep lunge feeding, allowing for further exploration of this population’s energetic landscape and fitness.”

“What I find exciting is that humpbacks have come up with complex tools allowing them to exploit prey aggregations that otherwise would be unavailable to them,” said Andy Szabo, AWF executive director and study co-lead. “It is this behavioral flexibility and ingenuity that I hope will serve these whales well as our oceans continue to change.”

This work was supported by Lindblad Expeditions – National Geographic Fund, ����Vlog�ٷ� Mānoa and a Department of Defense Defense University Research Instrumentation Program grant.

To get a unique look at how climate change is impacting marine mammals, ����Vlog�ٷ� News interviewed whale expert Lars Bejder, director of the at the University of Hawaiʻi at Mānoa , on how innovative technologies are helping experts monitor the health of marine mammals.

Bejder is a conservation biologist who focuses on marine mammals such as whales and dolphins in Hawaiʻi and internationally. He utilizes drones and specially designed sensors to gather data on cetaceans.

What species of marine mammals do you monitor?

Hawaiʻi has more than 20 species of whales and dolphins. We study between 8–10, and each one of those have different conservation issues and pressures.

The most iconic species we have in Hawaiʻi is the humpback whale that spends about three months a year here on their breeding grounds. We study the Hawaiian monk seals, which are only found here in Hawaiʻi and spinner dolphins, which is a coastal species. We also study pilot whales and false killer whales. Some generic threats for all of them are entanglements, ship strikes, noise pollution and climate change, and depending on the species, some are more or less affected by each of these.

What kind of tech are you using?

Using innovative technology such as drones and tags, we’re starting to get a good understanding of how humpback whales change from year to year based on climatic events. For example, a few years ago, when there was a large heat wave across the North Pacific, we saw significant declines in humpback whale health or body condition, which shows us how closely these animals’ health are linked to climate.

The two main new technologies that we use are calibrated drones and suction cup tags, the suction cup tags we use across species—so humpback whales, pilot whales, false killer whales and monk seals. We apply these onto those animals and acquire an incredible wealth of data. We use drones to estimate body condition and health of individuals and populations, and we use those across all of the different species that are here in Hawaiʻi.

How are you using tech to monitor humpback whales?

We have collected the world’s largest database on humpback whale health. And when I say health, it’s body condition which we measure through drones using calibrated lenses and custom fit altimeters. We’re able to fly these instruments repetitively over the same animals across ocean basins. So on the breeding grounds here in Hawaiʻi and also on the foraging grounds up in Alaska, we can really see how the body condition of these animals changes every season and every year. We have now measured 10,000 humpback whales. And when you think about it, the population estimate here in Hawaiʻi is between 12,000 and 14,000. So a significant amount of the animals are visiting Hawaiʻi. The fact that we also measure them up in Alaska allows us to see how much energy and condition they lose here in Hawaiʻi and vice versa.

How is climate change impacting humpback whales?

If you have a very good year, for example, the conditions are right, you’re going to have a lot of prey, and things are good for the whales up in Alaska. And a year later, you see that the animals are healthy, they’re large, and you’re getting calves. But what we’re also finding is when we have a bad year, for example, climatic events that are not good for prey items up in Alaska, the year later, we have significantly skinnier animals and less calves being born. And that’s really telling us something about the health of the oceans is portrayed through these animals. By simply flying a drone over animals, we can say something about the health of the ecosystem, and that’s really, really promising and exciting.

More than 10,000 images of humpback whale tail flukes collected by University of Hawaiʻi researchers have played a pivotal role in revealing both positive and negative impacts on North Pacific humpback whales, positive trends in the historical annual abundance of North Pacific humpback whales, and how a major climate event negatively impacted the population. Adam Pack, who heads the ����Vlog�ٷ� Hilo Laboratory, Lars Bejder, director of the ����Vlog�ٷ� Mānoa (MMRP) and graduate students Martin van Aswegen and Jens Currie, co-authored a study on humpback whales in the North Pacific Ocean, and the images—along with artificial intelligence (AI)-driven image recognition—were instrumental in tracking individuals and offering insights into their 20% population decline observed in 2012–21.

“The underside of a humpback whale’s tail fluke has a unique pigmentation pattern and trailing edge that can serve as the ‘finger-print’ for identifying individuals,” said Pack.

Starting in 1976, Pack’s mentor the late Louis M. Herman, founder and director of the ����Vlog�ٷ� Mānoa (KBMML), initiated collecting tail fluke images of humpback whales in Hawaiian waters alongside his students. The effort expanded to humpback whales in Alaska in 1980 and has continued every year since through the KBMML, the non-profit organization The Dolphin Institute which Herman and Pack founded in 1993, and in 2008 and beyond through Pack’s ����Vlog�ٷ� Hilo Marine Mammal Lab. In total, more than 30,000 whale tail images have been accumulated in waters off Hawaiʻi and Alaska resulting in one of the largest archival catalogs of humpback whales in the world. ����Vlog�ٷ� Hilo students are tasked with cataloging those images.

“Until recently, comparing photographs of humpback whales to each other to discover resightings of the same individual and develop individual histories over decades was done by eye, a slow and labor intensive effort,” Pack said.

The recent advent of AI image-recognition tools has revolutionized the process facilitating large-scale collaborations involving decades of data.

AI and humpback whale science

The ����Vlog�ٷ� team of researchers are part of the 76 co-authors who contributed to the findings recently published in which showcases the impact of artificial intelligence in the groundbreaking study. AI-driven image recognition was used to organize the tail fluke images of both the ����Vlog�ٷ� Hilo Marine Mammal Laboratory and the ����Vlog�ٷ� Mānoa Marine Mammal Research Program, along with thousands of other submissions from across the North Pacific, into an online humpback whale fluke matching program and database. The cutting-edge approach was led by Ted Cheeseman, the study’s lead author and the developer of research website .

“It shows how when we all pool our resources and talent together, we can learn remarkable things about humpback whales and their marine environment,” said Pack, who holds a joint appointment in the departments of and at ����Vlog�ٷ� Hilo.

A closer look at population increase and decline

The study showed a strong continuing recovery of North Pacific humpback whales from 20th century commercial whaling which ended in 1976 decimating the population to an estimated 1500–2000 whales. The study estimated 16,875 whales in 2002 growing to a peak of 33,488 in 2012. However, researchers also uncovered a critical period from 2014 to 2016 when an unprecedented marine heatwave adversely impacted marine resources including those in high latitudes which humpback whales rely on for sustenance. This decline in resources resulted in several years of poor reproductive and physical health for many humpbacks wintering in Hawaiʻi and summering in Alaska.

The population decline was especially noticeable in Hawaiʻi, a vital destination for thousands of humpback whales seeking warmer waters to mate, give birth, and raise their young. By 2021, the study found a staggering 34% decrease in the humpback whale population in these waters. It indicates that continued monitoring of North Pacific humpback whales and care for their marine habitats is essential.

For more go to .

To help protect and understand �Ჹ�ɲ���ʻ��’s whale populations, marine mammal researchers at the University of Hawaiʻi at Mānoa and Pacific Whale Foundation are utilizing cutting-edge non-invasive suction-cup tags to track endangered false killer whales and short-finned pilot whales. The CATS (Customized Animal Tracking Solutions) tags, equipped with cameras, hydrophones, accelerometers and depth sensors, provide insights into the daily lives of these marine species.

Lars Bejder, Jens Currie and their team have been deploying CATS tags, which were originally used on larger species such as humpback whales, and have evolved to cater to the specific needs of smaller species such as pilot whales and false killer whales. The tag is a non-invasive tool that separates from the whale when air is released into the suction cups.

“We started using these tags on smaller animals, which we haven’t done before,” said Bejder, director of the ����Vlog�ٷ� (MMRP). “That has opened up new windows to different species that we haven’t focused on before. Part of that has been the development of the next iteration of tags, which are meant for deep diving cetaceans. These tags are currently one-of-a-kind as far as we know.”

The deployment of CATS tags on these whales enables scientists to track their movements, diving patterns, and even record the sounds of their underwater environment. The tags are designed for deep-diving cetaceans, capable of withstanding pressures at depths of up to 1,000 meters. This allows researchers to explore the behaviors of pilot whales and false killer whales, shedding light on the impacts of human activities and the threats it could pose to �Ჹ�ɲ���ʻ��’s endangered false killer whale population. Understanding how false killer whales interact with prey can help inform the fishing industry on optimizing gear to reduce unintended interactions.

“The Main Hawaiian Islands Insular false killer whale is an endangered population here in Hawaiʻi,” said Currie, a PhD student in MMRP and director of Pacific Whale Foundation’s research. “There are only about 130 animals left in the population based on the latest estimate. It’s an important population to be studying and we can gain some impactful insights for conservation and management measures for false killer whales using these tags.”

Bejder and Currie emphasized the important role the public plays in spotting these marine mammals. To report sightings of false killer whales, call the NOAA Fisheries Hotline at (888) 256-9840, option 5. All research is being conducted under federal permits and IACUC approvals.

Humpback whale singing dominates the marine soundscape during winter months off Maui. New research revealed a daily pattern wherein whales move their singing away from shore throughout the day and return to the nearshore in the evening. The findings were led by the University of Hawaiʻi, in partnership with NOAA’s Hawaiian Islands Humpback Whale National Marine Sanctuary, and published in .

“Singers may be attempting to reduce the chances of their song being drowned out among the cacophony nearshore when whale numbers are high,” said Anke Kügler, lead author of the study who was a ����Vlog�ٷ� Mānoa doctoral student in the at the time of the research. “Further, we documented humpback whales moving closer to shore around sunset, possibly to avoid the offshore evening chorus of other animals.”

By using a combination of underwater listening devices and visual surveys, the research team was able to track both the physical movements and the acoustic patterns of whales in the high-density breeding grounds found in Hawaiʻi.

“This dynamic onshore-offshore movement of singers may be aimed at increasing the efficiency of the whales’ acoustic display, ensuring that other whales hear their songs,” said Marc Lammers, study co-author and research ecologist with NOAA’s Hawaiian Islands Humpback Whale National Marine Sanctuary.

“This is the first effort of its kind, to our knowledge, in which we used specialized acoustic sensors to localize individual singers relatively close to shore to understand daily variations in the distance to shore of these nearshore singers, their spacing, and their movement behavior,” said Kügler.

Important role for breeding

Humpback whale song is presumed to play an important role for breeding. The findings highlight the significance for male singers in an environment that is teeming with acoustic commotion. Through their approach, the team identified potential drivers for the daily onshore-offshore migrations—nearshore environments that are too crowded with whales during the day and offshore areas that are too noisy with the chorus of other animals in the evening.

“Discussions of noise pollution related to marine mammals have been dominated by concerns over anthropogenic noise,” said Kügler. “How natural sounds, including from other humpback whales, may interfere with their singing has been mostly overlooked. Humpback whales rely on acoustic signals. We explored possible causes of the observed patterns, which helps us understand how these whales adopt behavioral strategies that reduce interference from loud environments.”

Humpback whales are ecologically, economically and culturally significant in Hawaiʻi, and their singing is iconic around the world.

“It is our collective kuleana (responsibility) to be the koholā’s (humpback whales) stewards,” said Lammers. “This and future work contributes to fulfilling the sanctuary’s management plan by developing and implementing crucial research on humpback whales and their habitats to help maintain a healthy, sustainable population.”

Co-authors on the study include Adam Pack, professor of psychology and biology at , founder and director of the ����Vlog�ٷ� Hilo Marine Mammal Lab and co-founder of the LOHE bioacoustics lab; and Aaron Thode and Ludovic Tenorio-Hallé at Scripps Institute of Oceanography, University of California.

The work was supported by funding or in-kind donations provided by Oceanwide Science Institute, Greeneridge Science Inc., Whale Tales/Whale Trust Maui, the Linda and Jim Collister Fellowship, Pride of Maui, Trilogy Maui and Ultimate Whale Watch.

Scientists have found a new non-invasive way to identify a deadly virus in dolphins that could be a testing breakthrough. For the first time, researchers at the University of Hawaiʻi Health and Stranding Lab have successfully detected Fraser’s morbillivirus, which can cause respiratory and neurological disease, in the feces of a dolphin. The findings provide a new tool to identify and monitor threats faced by �Ჹ�ɲ���ʻ��’s marine mammals.

This is particularly important for �Ჹ�ɲ���ʻ��’s dolphin populations, where a disease outbreak could have devastating effects. Marine mammals, recognized as sentinels of ocean health, have an important role in maintaining the delicate balance of marine ecosystems.

Researchers collected feces from a stranded dolphin infected with the virus and conducted experiments to simulate the detection of the disease in seawater. The team demonstrated the surprising ability to detect Fraser’s morbillivirus in dilutions of feces in seawater at a level of 1 to 1,000. Using this non-invasive approach, testing poop collected from live animals in the wild will enable researchers to assess the health status of marine mammals with a hands-off approach.

“This is the first time that a pathogen responsible for mass mortalities of dolphins and whales, and that affects multiple organ systems other than the digestive tract, has been demonstrated in the feces of whales and dolphins,” said Kristi West, lead author and an associate researcher at the .

Testing in the wild

Morbilliviruses have been responsible for mass mortalities of dolphins and whales during outbreak events. This study recommends that permitted research vessels studying dolphins and whales collect fecal samples using flasks and nets to test for disease.

“It is logistically difficult to test live, wild dolphins for the presence of disease, and the current study provides a method that can be applied to detect infectious disease in live dolphins and whales,” said Cody Clifton, a co-author and graduate student at the .

The research was funded by the U.S. Navy and NOAA Fisheries. Reporting distressed or deceased marine mammals provides vital information for understanding causes of mortality and evaluating threats to protected species in Hawaiʻi and the greater Pacific. Sightings can be reported to the NOAA hotline at 1-888-256-9840.

A new tool uses facial recognition technology to identify individual whales and dolphins in the wild across 24 species. The research was led by University of Hawaiʻi at Mānoa (HIMB) PhD student Philip Patton and published in .

“From a conservation standpoint it is really useful to be able to recognize the same individuals over time because you can see what areas the individuals use,” said Patton. “You can also use this information to estimate population size and population trends.”

This multi-species photo-identification model based on a state-of-the-art method in human facial recognition was created for a organized by Happywhale.com that challenged engineers to develop a tool that could individually identify whales and dolphins using an algorithm. The algorithm engineers developed can identify characteristics such as scarring, pigmentation, size and more on individual dolphins and whales.

Accelerating information gathering process

The ����Vlog�ٷ� Mānoa studies these species using photography to inform management and conservation efforts for marine mammals in Hawaiʻi.

“When we go out and do these surveys like taking pictures of them out in the field, using an algorithm like this we can really speed up the information gathering process,” said Patton. “Once we get back to the lab we can run our photos through the algorithm and it will tell us who is there and then we immediately have some information to judge things like population, space use, etc. which are important for conserving Hawaiian whales and dolphins.”

Ecologically, dolphins are very social, and this new tool provides a way to observe dolphin social behavior in a non-invasive way.

“You can actually learn a lot of information from just recognizing the same individual over time and noting where you saw it,” said Patton.

The publication is the product of a massive collaboration, with 56 researchers from around the globe sharing their valuable image data—representing six continents and 24 species—to advance cetacean research and conservation.

The study included HIMB graduate students Liah McPherson and Jens Curry, and Patton’s faculty advisor Lars Bejder. Funding for Patton’s work came from the NOAA Quest Fellowship.

Video credit: Anna Schmalz

Using unoccupied aerial system (UAS), or drone photography, researchers from the University of �Ჹ�ɲ���ʻ�� at Mānoa (SOEST) are now able to determine the age-structure of free-ranging dolphin groups. This work will aid monitoring the health of dolphin populations and inform timely conservation efforts. The findings of the study that developed and applied this new technique were published in .

When dolphins come to the surface to breathe, they expose their blowhole and dorsal fin. By measuring the distance between the two, researchers can estimate their total body length. Since total length is related to age, the international team of researchers, led by scientists at the (HIMB) in SOEST, developed a technique of inferring age based on length for each measured dolphin within a group.

“This method can help us quantify the age-structure of free-ranging populations,” said Fabien Vivier, lead author of the study and doctoral candidate in the at HIMB. “Healthy dolphin populations usually contain a certain proportion of newborn, immature, and mature animals, while deviances from this distribution may be interpreted as a population growth or decline.”

Previous studies documented encouraging results of using drone photography to study and measure the size and body condition of large whales. However, no studies had applied this approach to assessing small dolphins, such as bottlenose dolphins.

“Because it is difficult working with free-ranging animals, we could not be sure if it would work out as planned,” said Vivier.

Quickly monitoring health

To understand whether analyzing UAS photos would be reliable for estimating the length of free-swimming dolphins, researchers collaborated with and tested the method on their bottlenose dolphins. They then tested the approach in estimating the age-class of free-ranging dolphins by collaborating with the in Florida, the world’s longest-running dolphin research project.

The Sarasota Dolphin Research Program provided the age, total body length, and distance between the blowhole and dorsal fin for many individuals in their study community. This offered the unique opportunity to calibrate and test the accuracy of the team’s age estimates and the inferred age-class based on length for free-ranging individuals.

“Our hope in developing and using this method is that we can quickly monitor the health of free-ranging dolphin populations,” said Vivier. “This may facilitate the detection of early signs of population changes, for example, a decrease in the number of calves, and provide important insights for timely management decisions.”

While this method was developed on bottlenose dolphins, it can be applied to other dolphin species, which will aid in monitoring and conservation. The team’s current research focuses on spinner dolphins in the main Hawaiian Islands.

This work was funded by , (Cooperative Institute for Marine and Atmospheric Research), the and .

–By Marcie Grabowski