Blood, bone and brainpower: A deep dive into sea otter DNA

Being a sea otter might sound simple: swim, snack, nap, repeat. Glorious.

Gidget is the face of the sea otter genome.

But the task before Annabel Beichman, a PhD candidate now in her fifth year at UCLA’s Department of Ecology and Evolutionary Biology, is monstrously complex. Annabel is investigating everything that makes up a sea otter, down to its DNA. She hopes what she learns will contribute to recovery of a species that plays a critical role in the health of coastal ecosystems.

Annabel’s effort to sequence the southern sea otter genome (which she wrote about for us last year) is tied to the Monterey Bay Aquarium by one of our exhibit otters, a 9-year-old female with a blonde, gray-streaked face, named Gidget. Through the DNA that Annabel has been laboring to sequence, assemble and annotate, Gidget will become the embodiment of the sea otter genome. And the work is nearly complete.

‘A reference point for generations’

“Gidget is going to be a reference point for future genetic studies of southern sea otters for years to come,” Annabel says. That research stands to help a species that has been listed as threatened for decades. So, she says, “Gidget’s contributing to the conservation of her entire species.”

California’s sea otters need more space to grow

Southern sea otters are a common (and adorable) sight off the Aquarium’s back deck. But the latest otter count shows the population isn’t growing at the pace we’d hoped it would. In order for the species to truly recover, otters need to return to their old habitats along California’s coast—places they haven’t inhabited for over 100 years.

For the second year in a row, California’s sea otter population index has topped an encouraging number: 3,090. That’s the minimum threshold before the U.S. Fish and Wildlife Service can consider delisting southern sea otters as a federally threatened species.

A southern sea otter with her newborn pup in the Monterey Bay Aquarium’s Great Tide Pool. Photo by Tyson Rininger

But the 2017 sea otter count is down quite a bit from 2016 levels, and even the three-year rolling average (the population index), on which federal wildlife managers base their decisions, is down by about 100.

Regardless of year-to-year variations, southern sea otters number far fewer today than they did historically, and their current geographic range represents just a fraction of the waters they occupied before fur traders drove them to the brink of extinction in the 19th century.

To reach the optimum sustainable population under the Marine Mammal Protection Act and the Fish and Wildlife Service recovery plan, the southern sea otter population would likely have to reach at least 8,400 animals in California alone.

A remnant colony of sea otters was rediscovered off the Big Sur coast in the 1930s. Photo © William L. Morgan/California Views Photo Archives

“What we really want to see is the population reinhabiting areas of its historical range,” says Andrew Johnson who, as conservation research operations manager for Monterey Bay Aquarium,  oversees the sea otter program. “We’ve seen how positively coastal ecosystems respond to the presence of sea otters—from the return of thriving kelp beds along the rocky coast, to renewed productivity of wetlands like Elkhorn Slough. We know that many other areas along the California coast would benefit significantly from sea otters’ return.”