The first of two month-long legs of the Mariana Archipelago Cetacean Survey has successfully completed. After NOAA cancelled many scientific surveys in 2020 due to the COVID-19 pandemic, the NOAA Ship Oscar Elton Sette has returned to operations in Guam. Onboard the ship is a team of satisfied scientists who have spent a month listening and looking for cetaceans (whales and dolphins). So far, they have sighted a beaked whale species not previously observed in the Marianas.
The purpose of this expedition is to survey for cetaceans and seabirds within the U.S. Exclusive Economic Zone of Guam and the Commonwealth of the Northern Mariana Islands. The ultimate goal of the survey is to assess the distribution and abundance of cetaceans in the Marianas. The first leg of the survey focused on the western portion of the islands. The second leg, already underway, is concentrating on the eastern portion of the islands and over the Mariana Trench.
Quaran-teaming in Guam
Considerable preparation goes into every ship-based survey, but it was an unusual undertaking this year. The 11-member team of scientists on the first leg completed pre-travel COVID-19 testing. Then they had a 14-day confinement in a Guam government quarantine hotel to ensure the health and safety of the team and the surrounding community. As the Sette steamed from its home port in Hawaiʻi to meet the science party in Guam, the science “quaran-team” received additional COVID tests and daily temperature checks. The government of Guam provided meals that the National Guard delivered outside each team member’s door at scheduled times.
The quarantine was not as isolating as you might think. The team participated in daily virtual training sessions covering the survey’s data collection protocols. Pre-assigned buddies checked in every evening, helping them get to know each other better before they teamed up onboard the ship. Outside the workday, they found their own personal ways to stave off boredom. They engaged in burpee challenges, quilt-making, and jigsaw puzzles. One team member completed a daily walking goal of 10,000 steps, walking loops around her room!
COVID precautions continued when the science team joined the crew on the ship. All aboard wore masks, checked their temperatures, washed their hands, kept their distance, frequently cleaned surfaces, and took additional COVID-19 tests. After the challenges of the past year, the team was grateful to survey again and willing to take these extra precautions to stay healthy and protect one another.
Cetacean Sightings on the Sette
As the Sette traversed the Marianas study area, the visual team searched for cetaceans using bigeye binoculars on the highest deck available: the flying bridge. Once the team spotted cetaceans, they estimated the size of the group, identified the species, and, if possible, collected photos and biopsy samples. Upon observing certain cetacean species, such as sperm whales or false killer whales, the visual team initiated specific observation protocols. These protocols occasionally lasted hours. While correlation does not equal causation, the team witnessed a tendency for these two species to emerge around the ship’s mealtimes (and sometimes at the same time!). Mealtimes are set, so one team member would take everyone’s meal orders to the Sette’s epic culinary stewards. These stewards went the extra mile and set food aside to enjoy when the sighting was over and things settled down.
The team made a particularly important cetacean sighting during this leg. Acoustic recorders had detected the Longman’s beaked whale near the Marianas in the past, but scientists had never seen them—until now. A group of Longman’s beaked whales surfaced in the northwestern portion of the islands, where our team visually identified and even photographed them! For many members of the science team it was also their first glimpse of this species in any location. It was a sweet reward for the extra steps needed to get the survey underway.
Listening for Cetaceans Underwater
Each day from sunrise to sunset, the acoustics team towed a hydrophone array behind the ship. This allowed the acousticians to estimate the locations of cetaceans when they vocalized. In addition to the towed array, they used a variety of equipment to eavesdrop on animals.
The Sette's crew helped the team deploy drifting acoustic recorders for up to 3 weeks to detect deep-diving cetaceans like beaked whales and Kogia species. All hands were on deck to help spot and retrieve the drifting recorders, especially at night. The Sette also retrieved three bottom-mounted acoustic recorders during the project. They recovered one instrument off Wake Island during the transit to Guam, and two instruments off the islands of Saipan and Pagan during this leg. While these recorders are usually stationed for 1–2 years, the Saipan HARP was down for more than 2 years while the Wake and Pagan HARPs were down for over 3 years due to the pandemic. The batteries in its release mechanism were well beyond their life expectancy, so the crew was relieved when the recorder came to the surface. The acoustics team also deployed sonobuoys during baleen whale sightings to collect recordings of their lower-frequency calls.
A dedicated seabird observer collected data on individual birds and foraging flocks throughout daylight hours. He also assisted the visual team as needed with sperm whale and false killer whale protocols. He documented a variety of shearwaters, petrels, terns, tropicbirds, and noddies. The keen-eyed observer added levity to daily reports by describing the variety of persistent boobies competing for the highest roost on the jackstaff, referring to it as the “Iron Perch.” Seabirds have a tendency to relieve themselves directly in line with the visual observers’ workstation—the seabird observer would often alert them by yelling “watch out!”
If the sun was up, chances were good that members of the science team were monitoring the water. Seas were often rough, compromising the visual team’s ability to see animals amongst the swells and waves. When viewing conditions were especially rough (Beaufort 7 or higher), the visual team maintained a “weather watch.” These consisted of one observer monitoring conditions until they improved (Beaufort 6 or lower) enough for all three visual observers to resume their search effort. The seabird observer and acoustics team typically persevered despite the weather, since seabirds were on the wing, still readily visible, and hydrophones were in the water.
After 29 days at sea and 2,100 nautical miles of search effort, the team successfully concluded the first leg of the expedition! In total, the team achieved the following:
- Sighted 31 groups of at least five cetacean species.
- Detected 123 vocalizations of at least nine cetacean species.
- Sighted 2,119 seabirds of at least 23 species.
- Deployed and recovered a total of 12 acoustic recorders that drifted for anywhere between 2 and 25 days and collectively recorded about 104 days worth of data.
The team recovered two bottom-mounted acoustic recorders off the islands of Saipan and Pagan and deployed two more that they will collect in another 1–2 years. Due to the lack of baleen whale sightings, the team made only a few attempts to deploy sonobuoys. Despite the consistently rough weather conditions, the first leg was an all-around success!
The second leg of the project is underway. Follow along with the survey on our 2021 Story Map!
All photos taken with research permit.