For the first time, scientists have calculated a detailed “energetic budget” for Â鶹´«Ã½‘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 Â鶹´«Ã½ 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 Â鶹´«Ã½ 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 Â鶹´«Ã½ 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 Â鶹´«Ã½

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 UH 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 Â鶹´«Ã½ 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 Â鶹´«Ã½ 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 Â鶹´«Ã½ 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 Â鶹´«Ã½ 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 (UH Hilo), UH Health and Stranding Lab, and HappyWhale. Â鶹´«Ã½ fieldwork was funded through UH 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 UH Mānoa Â鶹´«Ã½ 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 Â鶹´«Ã½, 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 UH 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 UH 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 Â鶹´«Ã½ at ²ÑÄå²Ô´Ç²¹ and , in celebration of World Ocean Day (June 8). “In the Wake of Whales” follows UH scientists as they study and monitor the annual migration of humpback whales from Alaska to Â鶹´«Ã½.

The video offers fascinating insights into one of nature’s most remarkable journeys—when thousands of whales travel nearly 3,000 miles to Â鶹´«Ã½ 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 Â鶹´«Ã½—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 °­Äå²Ô±ðʻ´Ç³ó±ð 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, Â鶹´«Ã½ 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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Leaving her home in India to attend the University of Â鶹´«Ã½ at Mānoa was a leap into the unknown for Ritu Krishna Raju. Having never traveled alone, the move came with excitement, but also the weight of being thousands of miles from her family.

Raju recounted her initial excitement mixed with the challenges of living far from her loved ones.

“When I first arrived in Â鶹´«Ã½, I was overwhelmed—excited, but also carrying the weight of being so far from home,” she shares in her commencement speech to be delivered at the fall 2024 ceremony.

Raju quickly discovered that the warmth of aloha extended beyond a word. She found a community and formed lifelong friendships with people who shared her values and passion. These friendships became her anchor, providing encouragement and laughter through the challenges of her journey. Surrounded by good friends, she learned the true meaning of ʻohana—family that extends beyond blood—and it deepened her connection to the islands and their people.

Marine biology attracts Raju to Â鶹´«Ã½

Drawn to UH Mānoa for its world-renowned marine biology program, Raju’s passion for the environment deepened during her studies. She interned with the at the , analyzing the vocal repertoire of endangered Hawaiian monk seals, gaining invaluable experience in marine mammal conservation. Raju also volunteered at Hanauma Bay Nature Preserve, where she educated visitors about marine life and the importance of protecting coral reefs, sharing her love for the ocean with countless tourists.

Her time at Mānoa was enriched by more than academics. She stretched her creative wings through dance performances and involvement at Kennedy Theatre, while also creating cherished memories with friends—whether hanging out in the courtyard near the Isabella Aiona Abbott Life Sciences Building or engaging with her peers as a Natural Sciences Ambassador.

Growing up, breaking through

More than three years later, she can look back and reflect on how much her experience at her journey at UH Mānoa has shaped her as a person.

“Growth often comes when you least expect it, and I’ve found that stepping out of my comfort zone has revealed more about who I am than I ever imagined. I’ve grown beyond the shy, unsure person I once was into someone who can navigate challenges with purpose and a deep respect for the world around me,” Raju said. “I am thankful for my family giving me their unwavering support that got me to where I am.”

As Raju wraps up this chapter of her educational journey she is considering graduate school to specialize in marine mammal biology with hopes to raise awareness about marine conservation back home in India. She will go knowing she has found and created a second home on the other side of the world with a community Raju can call her own.

University of Â鶹´«Ã½ 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 Â鶹´«Ã½, 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 Â鶹´«Ã½, 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 Â鶹´«Ã½ 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 Â鶹´«Ã½ 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 Â鶹´«Ã½ and Alaska. Researchers at the (MMRP) at University of Â鶹´«Ã½ 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 Â鶹´«Ã½ 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.

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 Â鶹´«Ã½ 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 Â鶹´«Ã½ is funded by ONR, NOAA Pacific Islands Fisheries Science Center, the Omidyar ʻOhana Fund at Â鶹´«Ã½ 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 Â鶹´«Ã½ 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, UH Mānoa and a Department of Defense Defense University Research Instrumentation Program grant.