When a hungry sea otter uses a rock to crack open a tasty mussel, it’s doing something unique among marine mammals: using a stone tool. Researchers are now revealing how this behavior makes it possible to study sea otters’ past through the lens of archaeology.
Sea otters use large stationary stones like anvils, to smash open mussel shells. Their hammering leaves distinctive marks on the rock. An ideal place to document this behavior is just a short drive up the coast from the Aquarium, near Elkhorn Slough.
Glacier Bay National Park in Alaska is home to more than twice as many northern sea otters (Enhydra lutris kenyoni) as all of California is to southern sea otters (Enhydra lutris nereis). Studying the thriving northern species may hold important clues for the future of the recovering southern species. In August, Monterey Bay Aquarium researcher Jessica Fujii spent two weeks studying the Glacier Bay population in the wild.
Jess is a senior research biologist with the Aquarium’s Sea Otter Program. She studies both wild sea otters and pups raised by surrogate otters so they can be returned to the wild—as was the case with two juvenile males earlier this month.
“Mostly I’m looking at sea otter behavior and foraging ecology—what they’re eating and what that may tell us about the rest of the ecosystem,” Jess says. “It involves a lot of going out in the field and watching the otters from shore.”
“It looks like a fishing boat, but it’s been converted for research purposes,” she says. “What used to be the fish hold is now sleeping quarters and storage.” With six or seven others aboard, “it was cozy; there’s not a lot of extra space.”
The trip was part of a longstanding collaboration between the Aquarium and researchers with the USGS Alaska Science Center. The two groups sometimes share insights and help each other observe or capture sea otters: “Having that crossover can be really helpful,” Jess says. “It’s also a way to make sure we’re maintaining comparable methods.”
Imagine you’re trying to eat a snack—a tasty sustainable fish taco, let’s say. But there’s no plate, no cutlery, and you can’t use your hands. Also, gravity is muted, so the taco has a frustrating tendency to float away between bites.
If this sounds difficult, you’re beginning to understand the challenge of being a hungry sea turtle, stuck with awkward flippers more useful for moving around than for grasping prey.
Still, sea turtles make do with what they have. And, as it turns out, they can (and do) use their forelimbs to corral, swipe and hold food.
Since 1984, Monterey Bay Aquarium’s Sea Otter Program team has worked to understand and protect southern sea otters (Enhydra lutris nereis). The population has slowly recovered from near-extinction in the early 1900s to become an icon of California’s Central Coast. Northern sea otters (Enhydra lutris kenyoni) have a similar story on the Southwest Canadian Coast: After going locally extinct in the early 1900s, they’ve been reintroduced and are expanding their range.
Today, the Hakai Institute is studying how the presence of sea otters is changing kelp forest ecosystems in a marine protected area along the British Columbia coast. This summer, Aquarium Sea Otter Research Coordinator Michelle Staedler and Senior Research Biologist Jessica Fujii traveled to Calvert Island to help monitor northern sea otters. Michelle shares her insights from the expedition.
The pilot banked the small plane, flying up a narrow waterway at the upper end of Calvert Island. Jessica and I saw below us a floating dock, several boats and red-roofed buildings nestled among the trees. This would be our home base for the next two and a half weeks.
Our destination: Hakai Institute’s Calvert Island Field Station, a coastal research facility 400 miles a northwest of Seattle. The only way to the island is by boat or float plane, weather permitting—but the frequent fog and storms don’t always cooperate.
What makes people different from other animals? Scientists used to think the ability to make and use tools was a distinguishing characteristic. That changed in the 1960s, when Jane Goodall observed chimpanzees using sticks to fish termites out of mounds. Now, crows, dolphins and sea otters make the short list of creatures that use tools.
Sea otters dive in shallow coastal waters to collect hard-shelled prey like sea urchins, mussels, abalones, clams and snails. Some shells, like the calcium carbonate armor that protects snails, are harder to crack than others—so otters sometimes use rocks as anvils to break them open.