The Hawaiian archipelago is teeming with marine life, and winter brings some of the most exciting activity of the year. It’s a season when many whale and seabird species travel to the islands. Migratory baleen whales such as humpback and minke whales are only found in Hawai‘i in the winter, when they seek warmer waters to breed. Others—including various types of dolphins—rely on this marine ecosystem year-round, but scientists have yet to uncover the details of their wintertime habits.
To close that gap, the Pacific Islands Fisheries Science Center launched a survey in late January 2026. Scientists spent 2 months monitoring these species around the main Hawaiian islands aboard the NOAA Ship Oscar Elton Sette. The mission, called the Winter Hawaiian Islands Cetacean and Ecosystem Assessment Survey, is only the second of its kind.
Six years after the first winter survey, researchers returned to better understand where, when, and how many whales and dolphins use this habitat. The data from these surveys feed into stock assessments, helping us track the status of these species and make informed conservation decisions. This work is especially important for high-priority species like false killer whales, including an endangered population that lives around the main Hawaiian islands.
Winter conditions at sea can be rough, with higher swells and lots of white caps. This makes animals harder to see. But NOAA scientists are experienced with scientific methods that rise to the challenge. During the survey, eagle-eyed visual observers spied more than 200 groups of whales and dolphins, even in difficult conditions. They documented humpback mothers with their calves, bottlenose dolphins riding the ship’s bow, and pantropical spotted dolphins leaping high into the air. Cutting-edge passive acoustic technology helped detect other whales and dolphins that could be heard but not seen.
In these photos, take a look behind the scenes of the survey and find out which species spend their winters in Hawaiʻi.
Working in a Winter Wonderland
Fourteen scientists, seen here gathered near the Oscar Elton Sette before departure, crewed the first leg of the survey from January 24 to February 22, 2026. Many of them returned to sea for the second leg, which ran through the end of March.
The survey had a special focus on baleen whales that frequent the main Hawaiian islands in the winter months. This includes humpbacks—the most commonly seen cetacean species during the survey.
In the winter, humpback whales migrate thousands of miles from Alaska and Canada to the warm, shallow waters of Hawaiʻi to mate, give birth, and raise their young. The survey team came across this humpback mother with her calf on February 2.
Over 2 months, the Sette traveled nearly 3,300 nautical miles around the main Hawaiian Islands. That’s even farther than a road trip from Seattle to Miami! To get a statistically sound count across such a vast area, the vessel followed predetermined tracklines. This precise method, known as line-transect sampling, helps scientists estimate the density of species encountered on a survey. The map above shows the tracklines the Sette followed, from the start of the survey through March 30. The red dots mark the locations of the sightings, alongside a list of the species and how often they were seen. The purple line indicates the boundaries of the overall survey area.
Big-Eyes: Scanning the Seas for Cetaceans
To search for animals during the survey, a team of six scientists posted a daily watch on the ship’s flying bridge. They used high-powered, long-range binoculars known as “big-eyes,” along with handheld binoculars with 7-power magnification. Big-eyes provide 25-power magnification!
Over 54 days, the survey team recorded more than 200 whale and dolphin sightings, spanning 19 species. Pantropical spotted dolphins were a common sight.
Other observed species included rough-toothed dolphins, Bryde’s whales, and short-finned pilot whales.
Researchers took more than 9,800 photos as they documented whale and dolphin sightings. They also added data about the sightings into a computer attached to the ship’s GPS, which captured course, speed, and position information.
When researchers spotted multiple animals, like these Fraser’s dolphins, the ship carefully approached the group. This allowed them to confirm the species and estimate how many individuals were seen.
At times, the crew were lucky enough to spot whales without the aid of binoculars, even in rough conditions. Here, they point out a minke whale surfing some waves alongside the ship on February 7.
This pair of bottlenose dolphins rode waves from the research vessel’s bow on March 14.
Taking to the Water to Collect Samples
When conditions allowed, the crew launched a small boat from the Sette. The small boat gives researchers the mobility they need to collect tissue samples from the animals to assess their genetics and health. They also collected water samples for environmental DNA (eDNA) analysis.
Back on the ship, the scientists processed the seawater they collected to detect eDNA—genetic material shed, such as sloughed skin, from marine animals. These animal “fingerprints” can provide a wealth of information about the biodiversity of the Hawaiian ecosystem.
Boing! Listening for Whale Calls with Underwater Recorders
More whales and dolphins often remain beyond the researchers’ line of sight—whether deep underwater or not visible in poor weather or rough seas. To improve animal detectability, the team used cutting-edge technology to listen for the sounds of animals beneath the surface while observers searched the sea’s surface with big-eyes. These tools included an acoustic towed array—a series of underwater microphones pulled behind the ship as it moves along the tracklines—and recorders attached to drifting buoys. This humpback whale call was recorded on February 4.
The researchers also used a type of hydrophone called a sonobuoy—a valuable tool for recording baleen whale calls. Sonobuoys freely float with ocean currents, listening for the low-frequency noises that whales make to communicate with each other. Researchers launched sonobuoys twice a day as the ship traveled along its tracklines, for a total of 132 deployments.
Along with humpbacks, the sonobuoys detected the calls of Bryde’s, fin, minke, and sei whales. Here, sonobuoy data shows a sei whale off the coast of Kaua‘i on February 17.
This minke whale “boing” call was recorded on February 4. Minke whales are known for producing a bizarre range of sounds, including the “boing” call. The source of this sound eluded researchers—and confused sonar operators—for decades. NOAA Fisheries scientists finally solved the mystery in 2002, confirming the “boing” call is unique to North Pacific minke whales.
Beaked whales are difficult to study because they spend much of their time underwater. They dive deeper and spend less time at the surface than baleen species. To find them, researchers used a tool called a Drifting Acoustic Spar Buoy Recorder, which lowers hydrophones nearly 500 feet into the ocean.
At right, researchers bring the recorder back aboard the ship; at left, a researcher downloads data it collected. The recorder drifts with the ocean currents, and the depth of the hydrophones makes for clear recordings of whale calls without background noise from the ship. During the survey, the team successfully deployed and recovered this type of equipment 16 times, with each session lasting between 2 and 16 days.
Researchers reviewed acoustic tracking computer displays of the towed hydrophone array in real time using open source acoustic software. Shown here is an acoustic detection of false killer whales as they clicked and whistled past the ship. False killer whales are NOAA Fisheries’ highest-priority cetacean species in the Pacific Islands region, given a documented decline in the population around the main Hawaiian Islands. We are making efforts to reduce fisheries bycatch of the population that resides further offshore.
Spotting Seabirds and Sunrises
Although the survey’s main focus was whales and dolphins, the team also collected data on seabirds. Studying seabird abundance and distribution gives us a fuller picture of the Hawaiian ecosystem. The team documented more than 2,600 seabird sightings, including 129 feeding flocks! Red-footed boobies, like this one taking a rest aboard the ship, were the most frequently seen species.
Ship surveys require scientists to spend weeks away from their loved ones and work long, physically demanding days. Even before dawn and after dusk, they are busy with tasks like lowering a conductivity, temperature, and depth instrument into the water to gather data about ocean health. But one perk of keeping these hours? Witnessing the sunrise over Maui.
All images and audio credited to NOAA Fisheries, taken under NOAA permit #25754.
