Using archaeology to uncover sea otters’ historical habitats

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.

A sea otter cracks open a mussel shell using a shoreline “anvil rock”.

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.

It’s an area that Monterey Bay Aquarium researchers like Jessica Fujii have monitored for years. Southern sea otters are a threatened species, and many of the orphaned pups reared by the Aquarium’s one-of-a-kind surrogacy program end up joining the wild population in Moss Landing Harbor. Years of data on sea otter foraging gathered by Aquarium researchers showed otters like to dine near the Bennett Slough culverts at the north end of the harbor.

“We have observations spanning about ten years in this location, both on wild animals that have no tags, and also sea otters that were raised at the Aquarium and successfully transitioned to the wild,” says Jessica, who has also monitored wild sea otters (while avoiding brown bears) in Alaska.

Diving into sea otter recovery in Alaska’s Glacier Bay

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.

When she’s not studying sea otters in Alaska during the summer, Jessica Fujii observes otter behavior around Monterey Bay. Photo by Michelle Staedler

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.”

This summer, she worked aboard the Alaskan Gyre, a 50-foot U.S. Geological Survey vessel.

“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 converted fishing boat Alaska Gyre was home base for scientists working in Glacier Bay.

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.”

Flippers, not fingers: Sea turtles’ surprising feeding strategies

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.

Sea turtles use their flippers in a multitude of ways to help them capture prey, like this green sea turtle in the Gulf of Thailand that’s grasping a jelly before it eats. Photo ©Rich Carey/Shutterstock.com

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.

Their behavior is the subject of a new publication by Monterey Bay Aquarium researchers Jessica Fujii and Dr. Kyle Van Houtan. It’s something that’s been noted in passing in scientific literature, but Jessica and Kyle say it’s a fascinating glimpse into the evolution of ocean creatures.

Visiting the Canadian cousins of Monterey Bay’s sea otters

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.

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Calvert Island and the Hakai Institute field station. Photo by Grant Callegari

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.

Winter Sea Otter Research on the West Coast of Canada from Hakai on Vimeo.

Sea otters are handy with tools

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.