Oregon But Not Forgotten: How Sea Otters Once Protected the State’s Kelp Forests

For Sea Otter Day, learn how a suite of specimens featured in the museum’s upcoming “From These Lands” exhibition illustrate the intertwined nature of sea otters and giant kelp in the Pacific Northwest

Sea otters once drifted along the Oregon coast, cracking open shellfish against their furry chests and weaving through thick forests of kelp that swayed just beneath the surface. Oregon’s kelp forests, dense with life and structured by just a few key predators, have experienced a notable decline along the state’s coastlines over recent decades. But important vestiges of this once-widespread ecosystem remain, often stored in museum collections and preserved in bone and fur.

One of these remnants — a sea otter skull collected in Oregon in 1875 — is featured in the upcoming exhibition “From These Lands,” opening June 18 at the National Museum of Natural History. The skull and accompanying urchin and kelp specimens illustrate howecosystems can fall apart when key predators disappear.

In the past, sea otters lived along North America’s Pacific Rim from Alaska to Baja California, playing an integral role in coastal ecosystems. They were also prized by coastal Indigenous communities, who sustainably hunted the marine mammals for food and fur for more than 10,000 years. But by the time the skull in “From These Lands” was collected in 1875, that long-standing relationship was already breaking down.

Beginning in the late 1700s, the maritime fur trade turned sea otters into one of the most valuable animals in the world. Hunters from Russia, Spain, and the United States targeted them for their pelts, which were prized for their density and warmth and used in products such as jackets and hats that were in vogue at the time. Unlike earlier subsistence hunting by Indigenous communities, this was large-scale commercial exploitation.

The results were rapid. By the early 1900s, sea otters had disappeared from Oregon entirely. What had once been a continuous population became a gap along the coastline, one that still exists today.

The disappearance of otters left a major hole in the region’s environmental puzzle. These predators, which are the largest members of the weasel family, are a keystone species, meaning their impact on ecosystems is far greater than their numbers alone would suggest. Sea otters feed on sea urchins, abalone and other invertebrates that graze on kelp. When otters and other urchin predators like sunflower sea stars are present, they keep populations of grazers in check.

However, sea otters and other key predators have largely disappeared from Oregon’s coast (the entire population of sunflower sea stars has declined by more than 90 percent due to the spread of sea star wasting disease). With fewer predators to keep them in check, these grazers, especially sea urchins, proliferate. “When you take otters out of the system, it fundamentally changes the ecosystem,” said Torben Rick, the museum’s curator of North American archaeology and a co-curator of “From These Lands.” “You start seeing what are called urchin barrens, areas where urchins overgraze and deplete kelp forests.”

The decline of kelp forests can prove disastrous for the rest of the coastline. As one of the most productive ecosystems in the ocean, kelp forests provide habitat for fish and shellfish, reduce wave energy that causes coastline erosion and store carbon. Without sea otters to control grazing species, these underwater forests can collapse, leaving behind simplified environments with far less biodiversity. 

A small but telling tableau of specimens in “From These Lands” illustrates these ecosystem relationships. The sea otter skull and a pelt from Alaska are joined by a swirling giant kelp specimen and a pair of purple sea urchins. (A diet of purple sea urchins even stains some sea otters’ teeth and skulls purple.) The collection illustrates the connections between predator, prey and habitat. Together, they show how the removal of one species can reshape an entire ecosystem.

The skull also serves as a historical reference point. Like other museum specimens, it captures a moment in time that scientists can compare with modern environmental conditions. In the same way preserved amphibians have helped researchers understand the long-term effects of pollution, sea otter specimens help scientists study population change, genetics and environmental shifts over time.

Recent research has expanded what scientists can learn from these collections. By analyzing dental calculus, the hardened plaque on the teeth of specimens, scientists have been able to extract DNA and gain new insight into historical sea otter populations. These techniques allow researchers to study specimens collected more than a century ago without significantly damaging them, adding new value to museum collections.

"Sea otters were never just another species — they were part of the system that held it all together.”
— Torben Rick, National Museum of Natural History's curator of North American archaeology

The loss of sea otters along the Oregon coastline reverberates beyond local ecosystems — the marine mammals also hold deep cultural significance. For local Indigenous communities, sea otters have been part of daily life and identity for thousands of years. Their disappearance was not only an environmental loss but a cultural one.

“There’s a really strong cultural significance for sea otters in every coastal tribe here,” said Chanel Hason of the Elakha Alliance. The organization, named after a Chinook trade word for sea otter, works with tribes, scientists and conservation groups to restore the species to Oregon waters.

Efforts to bring sea otters back have been challenging. In the early 1970s, wildlife managers relocated otters from Alaska to the Oregon coast as part of a broader reintroduction effort. The animals survived and reproduced for a time, but within about a decade, the population disappeared. Researchers believe the number released may have been too small, and at the time, there were limited tools to track their movements or survival.

Today, scientists have a better understanding of sea otter biology, genetics and habitat needs, along with improved tracking and transport methods. Even so, reintroducing a species remains complex and requires careful planning, regulatory approval and coordination with local communities.

“With species like sea otters, you can’t just drop them back into a place and expect it to work, which is why the careful work the Elakha Alliance and other groups are doing is so important,” said Rick.

As researchers and conservation groups continue to explore the possibility of reintroducing sea otters to Oregon, historical specimens like the skull in “From These Lands” remain important. They help document what ecosystems looked like in the past and provide context for current and future restoration efforts.

“Sea otters were never just another species along this coast — they were part of the system that held it all together,” said Rick. 

Paul Holm | Read More

Paul Holm is a science writing intern at the Smithsonian’s National Museum of Natural History who primarily writes for the Smithsonian Ocean Portal. The Ocean Portal perfectly complements Paul’s love of the ocean and his passion for journalism. He recently completed his writing degree at the Savannah College of Art and Design and will complete a master’s degree in journalism at the University of Texas at Austin. He is an avid outdoorsman, preferring to spend as much time as possible outside, running, biking, hiking, and doing pretty much anything else under the sun.