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Sea Otter Savvy

Sea Otter Science And Community Outreach

 Sea Otter Savvy in Japan

A Research Intern’s Journey to the Otter Side of the World
By Samantha Hamilton

The author tracking tagged sea otters at Hopkins Marine Station in Pacific Grove, CA. Photo by Leilani Konrad

japan Fig 1Fig 1 The author collecting data on human disturbance to sea otters in Elkhorn SloughSundays aren’t for rest and relaxation; here at Sea Otter Savvy, they mean adventure. Since becoming an intern last year, my typical Sunday is spent behind binoculars observing wild sea otters at Elkhorn Slough (Fig. 1). So much time has been invested there that I’ve come to see the estuary as a second home and its otters as old friends. Weekends this last September passed in the same way—scoping for otters and recording their behaviors—but far from the same place. In an exciting shift I traded the familiar Slough for Japan, where I participated in data collection for ongoing sea otter studies in Dr. Yoko Mitani’s lab.

Their research took me to the remote Hokkaido coast, which represents the eastern-most extent of the current species range. Fewer than 50 individuals can be found there, and we owe this to the historic fur trade that infamously culled sea otter populations around the Pacific Rim (Ravalli, 2009). The species was absent from Japan for over a century before transient individuals began turning up in the late 1900s (Hattori et al., 2005) and a permanent population took hold in 2014 (Kogen, 2023). Today the country’s sea otters are on the road to recovery, but progress has been slow and research limited. Dr. Mitani and her lab are among the few paying scientific attention to this little-studied population, and I joined in on their two-week excursion to eastern Hokkaido (Fig. 2) to learn more about this emergent population.

Fig 2 Map of stops made in eastern Hokkaido during the author's trip.

First Stop: Moyururi Island

After a plane flight, a bus trip, and three train rides, this jetlagged intern made it to the eastern Hokkaido coast. From there, our team traveled by boat to the nearby Moyururi Island. This study site is one of two known locations in Japan that supports a permanent sea otter population. The island is 0.12 square miles in area, which is equivalent to 1/250th of San Nicolas Island’s size. Its coast has lush eelgrass beds, rich prey, and minimal human activity—all conditions that attract sea otters to the small island.

Prey aren’t just abundant off Moyururi Island, but they are also exceptionally diverse. We know this from foraging observations made during the trip, which revealed a wide range of species eaten by the island’s sea otters. Bivalves made the most common and crunchiest snacks, with the sound of cracking shells sometimes carrying all the way to our boat. When we weren’t watching sea otters forage, the Mitani team was busy conducting benthic surveys. They consisted of a professional diver collecting invertebrate samples from a total of 22 sites. Once brought to the boat, the invertebrates were counted, measured, and packaged for further processing at the Hakodate Research Center. These surveys provide information about the density, size, and biomass of prey around Moyururi Island—information important for understanding prey availability and the impact of otters on benthic communities.

Focal follows represented another priority during fieldwork. In teams of two, we observed an individual otter and recorded its behavior each minute over a 30-minute duration. This method of data collection allowed us to measure sea otter activity budgets, or the frequency and duration of various behaviors. The target of my first focal follow was an active mom-pup pair, who spent the observation period foraging for bivalves and interacting with each other. They were a fun duo to watch, and my memory of their frisky play fighting has become my most treasured souvenir from the trip.

A census was also conducted from boat around Moyururi Island and the adjacent Yururi Island. With binoculars in hand, we scanned for sea otters in the choppy water and recorded the locations of those we were able to spot. Together, the islands were found to support just over a dozen individuals. This figure may seem small, but it was smaller just decades ago. The sea otter count has gradually increased since the first sighting was made in the area in 1986 (Hattori et al., 2005)—an encouraging sign of their recovery. The Mitani lab will keep tracking their numbers, and fingers crossed that they go up from here.

Hokkaido sea otter mom and pup having a nap. Photo by Michel Godimus (

Second Stop: Cape Kiritappu

It’s our goal to hit the water and collect data off Moyururi Island daily, but sometimes the weather has other plans. When there is strong wind or high swell, fieldwork is abandoned and we try to make the best of these days by exploring our surroundings in eastern Hokkaido. On one such day, the Mitani team decided to visit Cape Kiritappu (Fig. 3A & B)—the other site in Japan where a permanent sea otter population can be found (Kyodo News, 2020).

japan Fig 5Fig. 4 Cape Kiritappu sea otter resting in heavy fog. Photo by Samantha HamiltonUpon arriving, Cape Kiritappu was shrouded in a blanket of dense fog. We walked along the edge of its steep cliffs, squinting hard and hoping to make something out in the ocean. Our optimism gradually began to evaporate as none of us could find the sea otters we came for. But as we started to retrace our steps, I spotted a dark dot in the fog bank and grabbed my binoculars to confirm my suspicions. Eureka! The dot, though barely visible, proved to be a resting sea otter that had no idea how thrilled the researchers above were to see it. Between sharing smiles and exchanging high-fives, we took turns looking at the sleepy creature lazily drifting on the ocean surface (Fig. 4).

The otter came into and out of visibility so many times that I couldn’t help but think that it might have been a figment of my imagination, a too-good-to-be-true apparition floating in a dreamy cloud. Perhaps I so desperately wanted to see the species succeed in recolonizing Japan that I conjured one up. Knowing that Kiritappu may have once supported more sea otters made it difficult to accept the lone dot that now rested off its coast. As we headed out, I wondered if we would ever be able to bring back the Kiritappu of the past and replace the one-off, phantasmal otter with more.

Fig. 3 (A) View off a cliff’s edge and (B) steps at Cape Kiritappu. Photos by Samantha Hamilton

Third Stop: Ochiishi

In the small coastal community of Ochiishi, the Mitani lab prepared to deliver presentations at two of the town’s schools. Students at Ochiishi Junior High and Elementary Schools were eager to learn about the recovering sea otters in their backyard and welcomed us with abundant enthusiasm. During the lecture, they gazed in amazement at Dr. Mitani’s slides (Fig. 5A), surprised that the otters were much bigger than they imagined, and asked thoughtful questions about their prey and pups. Thanks to the Nemuro City Museum of History and Nature, students were able to feel just how thick sea otter fur is by petting an adult pelt (Fig. 5B). The museum’s curator also brought in a taxidermized pup, which gave students their first up-close encounter with such a young sea otter.

I was blown away by the students’ high level of engagement and feel confident that we inspired many to become lifelong sea otter champions that day. Dr. Mitani’s final message—to take good care of the ocean and strive for peaceful coexistence with its creatures—seemed to resonate with them, and we left the schools hopeful that the next generation will make better stewards than our own.

Fig. 5 (A) Dr. Mitani giving a lecture to Ochiishi Junior High School students and (B) author with adult male Asian sea otter pelt.

Final Stop: Home

japan Fig 7Fig. 6 Eastern Hokkaido train tracks taken for the author's homeward journey.Before I knew it, my one-of-a-kind adventure in eastern Hokkaido was coming to an end and it was time to catch the train out. Packed and ready to go, I hitched a ride to the small station (Fig. 6) from a Mitani lab member and claimed a window seat on the train to wave goodbye. A surge of gratitude came over me as the train started to pull forward—gratitude for the Mitani lab’s hospitality and for the opportunity to see the recovering population firsthand. For sea otters to overcome the odds and call Japan home again is nothing short of a miracle. Their resilience has enabled them to evade near-certain extinction, and today they are on track for a conservation success story. I look forward to reuniting with these sea otters, whenever that may be, and until then I will root for their continued growth and expansion from afar.

        またね、ラッコ! (Catch you next time, otters!)


Hattori, K., Kawabe, I., Mizuno, A. W., & Ohtaishi, N. (2005). History and status of sea otters, Enhydra lutris along the coast of Hokkaido, Japan. Mammal Study, 30(1), 41-51.[41:HASOSO]2.0.CO;2

Kogen, M. (2023, August 1). Sea otters raise more pups in Hokkaido as range extends. The Asahi Shimbun. 

Kyodo News. (2020, October 3). Rare wild sea otters create tourist boom for Hokkaido town.

Ravalli, R. (2009). The near extinction and reemergence of the Pacific sea otter, 1850-1938. The Pacific Northwest Quarterly, 100(4), 181-191.

About the author

Samantha Hamilton has a Master of Science from Johns Hopkins University, and has just been accepted as a PhD candidate at Kyoto University where she will be studying the foraging ecology of Hokkaido's sea otters under Dr. Yoko Mitani. Samantha has been research intern for Sea Otter Savvy since 2022. 

japan author bio