Sierra Fullmer is a Research Project Technician with Upwell who assists with leatherback aerial surveys to support vessel-based research on sea turtles foraging off the US Pacific coast. She also develops processing and management tools for current and archival aerial survey data used in habitat-based density models. Sierra has a BS in Marine and Atmospheric Science from the University of Miami in Florida and is completing her Master’s in Marine Science at Moss Landing Marine Laboratories through California State University, Monterey Bay.

Figure 1. Pacific Northwest aerial observation team in NOAA Twin Otter (left to right: Scott Benson, Karin Forney, Katherine Whitaker, Andy Maurer, Sierra Fullmer; not pictured: Vicky Vasquez; Photo: Sierra Fullmer).

Last fall, as a member of the NOAA and Upwell leatherback turtle aerial survey team, I flew more than 120 hours of coastal transects off the Pacific Northwest and California in a small two-engine plane over the course of six weeks. Although we flew over a lot of ideal leatherback foraging habitat with brown sea nettle aggregations (Chrysaora fuscescens) and Mola mola (which, like leatherbacks, also eat sea jellies), we did not spot any leatherbacks. It is important to note that there appears to be annual variability within the West Pacific leatherback population; some years a larger proportion of the population remains closer to the nesting beaches decreasing the likelihood of sightings in their foraging grounds. Furthermore, as the leatherback population has declined significantly over the last three decades(1), surveying during these years has become more difficult. These challenges highlight the importance of continuing these surveys, given the high financial investment for limited return of leatherback sighting data.

Figure 2. Aerial observer Sierra Fullmer in the belly observer position, looking out over the water (Photo: Vicky Vásquez).

Even during years when our teams spot few or no leatherbacks, our surveys still collect important information on leatherback habitats and the distribution of other marine wildlife we observe. Sometimes we even make unexpected discoveries! For example, during one survey last fall I was lucky to witness an incredibly rare sighting off the coast of California that I will never forget. It was on the last survey line of the day while I was lying in the cargo hold, looking down through a window on the bottom of the plane in the “belly position” as water, animals, and kelp passed by at 100 knots.

Out of the corner of my eye, I spotted a shape I’d never seen before, though I was fairly confident it was whale sized. “Sighting! What was that?! Can we circle left?” I called out. Vicky, my teammate in the left bubble window, agreed she also saw something new and unknown. Once our pilot circled back to the spot, Dr. Karin Forney, the lead of the aerial observation team, spotted two animals and identified them as a mother-calf pair of Baird’s beaked whales (Berardius bairdii)! Karin’s identification led to a mad scramble to find the telephoto camera - digging the case out of the pile of research gear, finding the charger that slid under my seat, throwing the battery in, and opening the camera window.

Figure 3. Aerial observer Sierra Fullmer capturing species identification and training images in the Aspen Helicopter's Observer Partenavia (Photo: Vicky Vásquez).

Boy, did I underestimate the challenge of photographing a 30-foot whale with a small calf from 650 feet in the air while circling at approximately 100 knots, lining up the shot to avoid the glare of the sun, zooming in on the whales, and constantly manually focusing my lens. Sounds simple, right? My first images were “trials”, but I knew I was limited on time. These whales don’t stay at the surface long. Luckily, on the second pass I managed to get a photo to prove our story to those back home.

Figure 4. Baird's beaked whale cow/calf. (Photo: Sierra Fullmer); NMFS Permit No. 22306.

We circled the whales for about 5 minutes before they disappeared, likely diving to resume their foraging deep below the sea surface. We then circled back to finish our survey, and packed up to head home. As I sat up, I heard Karin call out “Is that another beaked whale? ” My center of gravity suddenly shifted as the plane banked right to circle back. It was indeed a Cuvier’s beaked whale (Ziphius cavirostris), and I again made a mad dash for the camera.

Figure 5. Cuvier's beaked whale. (Photo: Sierra Fullmer); NMFS Permit No. 22306.

We had spotted two beaked whale species within a radius of five nautical miles!

Beaked whales are known for their deep-diving capabilities and can dive 3,300 or more feet to forage(2,3). That’s deeper than two Empire State Buildings! The Cuvier’s beaked whale also holds the current record for longest dive duration at three hours and 42 minutes(4); the human record is under 25 minutes(5)! Due to these long dive times and short surface times, often only a couple minutes, beaked whales are very uncommon to see, even for researchers who have been surveying for years. At the beginning of each flight, we like to call out our sighting wishes for the day (mine is often an otter or twenty – in addition to leatherbacks of course), but we only ever dream about seeing multiple rare species like beaked whales in a day. Without the photos as proof, our colleagues might not have believed us. In fact, they thought we were joking when we first told them.

Beaked whales are similar to leatherback turtles in that they are also capable of diving to extreme depths, upwards of 4,000 feet deep for up to 85 minutes when foraging(6). They also both have unique physical traits that help their bodies adapt to the difference in pressure and oxygen deep underwater. However, Pacific leatherback sightings are rare due to both their diving behavior, and their population declining 80-90% in the last three decades1. The main threat they face is accidental capture in commercial and artisanal fishing gear throughout most of the Pacific Ocean as they migrate from breeding grounds in Indonesia and the Solomon Islands to their foraging grounds in the eastern North Pacific(6).

Aerial surveys provide unique opportunities to identify and experience animals that may be harder to find on shore or by boat and are the only means for estimating abundance and density of cryptic leatherback turtles. Although observation efforts are confounded by prolonged dive times, the bottom line is that we are likely encountering fewer leatherback turtles because their population numbers are dwindling. Our continued survey efforts provide a one-of-a-kind opportunity to learn more about leatherbacks and other elusive marine animal species. We conducted these surveys with funding received from the Bureau of Ocean Energy Management, California’s Ocean Protection Council, and other Upwell supporters. Hopefully next year we will find more leatherbacks! Until then, I’ll continue practicing my camerawork and sharing the species we see with the community around us.

Benson SR, Forney KA, Moore JE, LaCasella EL, Harvey JT, Carretta J V. A long-term decline in the abundance of endangered leatherback turtles, Dermochelys coriacea, at a foraging ground in the California Current Ecosystem. Glob Ecol Conserv. 2020;24:e01371.
NOAA. Species Directory: Cuvier’s Beaked Whale [Internet]. NOAA Fisheries. 2023 [cited 2023 Oct 10]. Available from: https://www.fisheries.noaa.gov/species/cuviers-beaked-whale
NOAA. Species Directory: Baird’s Beaked Whale [Internet]. NOAA Fisheries. 2023 [cited 2023 Oct 10]. Available from: https://www.fisheries.noaa.gov/species/bairds-beaked-whale
Quick NJ, Cioffi WR, Shearer JM, Fahlman A, Read AJ. Extreme diving in mammals: first estimates of behavioural aerobic dive limits in Cuvier’s beaked whales. J Exp Biol. 2020;223:jeb222109.
Suggitt C. 56-year-old freediver holds breath for almost 25 minutes breaking record [Internet]. Guiness World Records. 2021 [cited 2023 Oct 10]. Available from: https://www.guinnessworldrecords.com/news/2021/5/freediver-holds-breath-for-almost-25-minutes-breaking-record-660285
NOAA. Species Directory: Leatherback Turtle [Internet]. NOAA Fisheries. 2023 [cited 2023 Oct 10]. Available from: https://www.fisheries.noaa.gov/species/leatherback-turtle