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Saving the Sea Otter 

Feds find reintroduction into Northern California possible but more research needed

click to enlarge A territorial male sea otter in Moss Landing forages for shore crabs in the pickleweed. USFW notes this photo was taken by a trained wildlife biologist using a 400 mm lens from more than 60 feet, the minimum distance recommended to avoid disturbing the animals.

Photo by Lilian Carswell/USFWS

A territorial male sea otter in Moss Landing forages for shore crabs in the pickleweed. USFW notes this photo was taken by a trained wildlife biologist using a 400 mm lens from more than 60 feet, the minimum distance recommended to avoid disturbing the animals.

On rare occasions, a sea otter makes an appearance on the North Coast.

Locally extinct since around the turn of the 20th century, the last confirmed sighting was in 2015, when one was filmed frolicking in Humboldt Bay. In less fortunate cases, remains of two sea otters were separately discovered washed up on area beaches over the last decade. Genetic testing showed one was part of the northern population that extends from Washington state to Alaska, while the other was the southern subspecies that lives along the Central California coast, between Santa Barbara and San Mateo counties.

How and why the furry sea creatures with animated faces that have launched a thousand memes found their way to Humboldt — as well as the origin and outcome of the sea otter seen alive and swimming near the North Jetty — is unknown because none had tracking devices.

Although male sea otters are sometimes prone to wander long distances, getting here would have meant traveling several hundred miles, while evading their ocean nemeses — the great white shark and orca —and finding enough places to forage along the way.

There is, however, a glimmer of possibility that North America's smallest marine mammal could return to the region — not just as wayward visitors but permanent residents, opening a new chapter for the threatened species. Otters' reintroduction would also bring the potential added benefit of helping restore the North Coast's beleaguered bull kelp ecosystem by bringing back a keystone predator missing for generations.

The U.S. Fish and Wildlife Service is currently weighing whether to transplant sea otters to select sites in portions of their former territory — from the Bay Area to Oregon — in an attempt to aid their recovery and eventually bridge the more than century-long separation between southern sea otters and their northern counterparts.

"Reintroducing sea otters to Northern California and Oregon would help increase genetic diversity and long-term sustainability of sea otters in the wild by beginning to reconnect the northern sea otter and southern sea otter subspecies," Lilian Carswell, USFW's southern sea otter recovery and marine conservation coordinator, said in an email to the Journal. "Scientists have identified that Northern California and Oregon have suitable habitat to support sea otters, and this area constitutes the largest remaining gap in the formerly continuous historical range of the sea otter."

The agency released a report over the summer that found reintroduction is biologically, socioeconomically and legally feasible but the 200-page assessment came with the caveat that far more research needs to be done to narrow down potential landing spots, as well as additional public outreach and studies on possible socioeconomic impacts.

USFW did not take a position on whether to proceed.

"In the assessment, we determined that reintroducing sea otters to parts of their former range could help restore nearshore ecosystems, increase gene flow between sea otter populations, benefit the threatened southern sea otter and provide overall economic gains to coastal communities," Carswell said. "As we go forward, we'll be working with scientists and a broad range of stakeholders to make sure any actions we're considering are fully vetted and that we're taking into account input from everyone who might be affected."

Earlier this year, the Center for Biological Diversity filed a formal petition asking USFW to immediately start the process over "a large stretch of the West Coast," noting in a statement that the effort is integral to protecting the southern sea otter by enhancing the subspecies' ability "to intermingle, enhancing genetic diversity and helping them adapt to changing environmental conditions." Geographically diversifying the population would also provide a buffer to risks from catastrophic localized events, like an oil spill.

"Bringing the sea otter back to the broader West Coast would be an unparalleled conservation success story," Kristin Carden, a former senior scientist with the center who authored the petition, said in the statement. "Not only would the sea otters thrive, but they would also help restore vital kelp forest and seagrass ecosystems."

Once believed to have numbered into the hundreds of thousands across a vast Pacific Ocean expanse from northern Japan to Baja California — including the coastal waters of Humboldt, Del Norte, and Mendocino counties — sea otters were hunted to the brink of extinction during the 1700s and 1800s by a maritime fur trade that coveted their luxuriant pelts, which are the thickest of any mammal.

By the time a 1911 international treaty made killing sea otters illegal, only a few hundred remained in small, isolated pockets, mostly around Alaska, where they now stand at around 25,000. In California, sea otters were considered lost until 1938, when approximately 50 were discovered to have found a haven in a remote section of the Big Sur coastline.

Over the ensuing years, extensive conservation efforts have seen that remnant colony — the forebearers of the entire current southern sea otter population — grow to some 3,000 otters.

Monterey Bay Aquarium has been at the forefront of that work for decades, with its sea otter research and work in rescuing, rehabilitating and releasing the animals contributing to the USFW feasibility assessment report on a number of levels, according to Aimee David, vice president for U.S. and California ocean conservation at the aquarium.

"So, we have an interest in recovering southern sea otters," David said. "We have also done a lot of work in researching the relationship between southern sea otters and their ecosystems, and have seen this work in practice play out, where we see the essential role sea otters play in the healthy kelp forests, in the healthy seagrass meadows, and we have seen those benefits increase with the presence of otters."

She also notes the sea otters' status as an economic driver on the Central Coast, bringing in tourists hoping to capture a glimpse of the "iconic species" swimming in local bays or lounging in the kelp beds wrapped with seaweed tendrils to avoid floating away while they rest, sometimes holding paws.

One "promising method of reintroduction" developed at the aquarium over the last 20 years has adult females in the sea otter exhibit act as surrogate moms for stranded pups. They're able to pass on important life skills, like how to groom and search for food, which allows most of the young to be released back to the wild, David said, with a high success rate of the animals staying and thriving in new environments.

In previous attempts, like a relocation effort at San Nicolas Island off the coast of Santa Barbara in the late 1980s, up to 90 percent of the animals initially placed in a new location were lost, both from dispersal — attempts to return to where they came from — and death, the USFW report states.

But because the young rehabilitated sea otters don't have ties to a particular territory, those released from the aquarium to an estuary near Monterey Bay in recent years have shown an ability to adapt well to new places. Along with other lessons learned from previous reintroduction efforts — including some success keeping sea otters in pens at new release sites for a period of time — incorporating surrogate-raised pups into the mix shows potential for mitigating the dispersal issue. But, the assessment states, "This approach has never been tested as a method of establishing a new population in an area that is entirely unoccupied."

Potential losses are inherent in any attempt, the assessment notes, but not moving forward comes with its own risks.

"As long as the bulk of the southern sea otter subspecies remains concentrated in one isolated stretch of coast, it is vulnerable to catastrophic events, such as a large oil spill, that could effectively eliminate the source population," the assessment states. "The risk of such an unforeseen event, even if extremely unlikely in any one year, poses a significant threat to the southern sea otter while waiting for the population to expand on its own. ... We therefore conclude there is a risk with inaction, and that risk is greatest for the threatened southern sea otter due to diminished adaptive capacity and a lack of redundancy in populations."

While the southern sea otter population descends from a finite gene pool, decades of research indicate a low level of diversity is not the primary reason the subspecies isn't recovering at higher levels, said Jess Fujii, manager of the Monterey Bay Aquarium's Sea Otter Program.

Instead, Fujii said, disease, pollution and deadly shark-bites have proven to be a more formative barrier, with the latter seen as one of the major reasons the southern sea otters' range has not expanded in the last 10 years. Fujii added, "Something like a reintroduction could be a way to overcome that ... by sort of getting beyond that almost physical obstacle."

Carswell agreed. Without human intervention, she said, it's "very unlikely that sea otters will recolonize the Northern California or Oregon coast within our lifetime."

As for the sightings of sea otters in Humboldt, Carswell said, "The fact that sea otters are occasionally found transiting the Northern California and Oregon coast does suggest that one or more new populations established in this gap could serve as stepping stones to reconnect the northern and southern subspecies."

In addition to aiding sea otters, reintroduction carries potential benefits for local marine habitats, with the animals — which need to consume 25 percent of their body weight in food each day — playing a key role in checking sea urchin populations in the kelp forests where they currently live.

But, like most aspects of potential relocation, there are still a number of unknowns in how that might play out along the North Coast, where a series of ecological events over the last decade wreaked havoc on the region's bull kelp forests, with huge swaths stripped bare by marauding armies of purple urchins, resulting in the collapse of the area's red abalone stock.

The USFW assessment notes that "multiple stakeholders" have raised questions about whether a relocation attempt in the region could interfere with efforts to restore the complex ecosystem. The most troubling question is whether the sea otters would eschew the purple urchins currently existing in a near starvation state in favor of their other shellfish staples, like crab or the perilously endangered abalone. But if the otters primarily feed on the urchins, the effects could be impactful.

"If the return of sea otters to the Northern California coast resulted in the rapid recovery of kelp cover that has been documented elsewhere, it would provide a significant boost to restoration efforts for that ecosystem and the species that depend upon it, including the red abalone and red sea urchin," Carswell said.

"There is some uncertainty as to how quickly such changes might occur, however, due to some complicating factors."

Those include how quickly sea otters "might manage to exert positive influences in a kelp forest already reduced to an urchin barren." And, with suitable sea otter habitat only occurring in "a patchy mosaic along the coast," Carswell said the animals' ability to "enhance degraded kelp forest systems over a significant extent of coastline" would likely not occur anytime in the near future, even if reintroduction happened soon, due to "the slow population growth of reintroduced sea otter populations."

Ultimately, the core of any successful reintroduction effort will come down to not only finding viable sea otter habitat but an extensive exploration of potential cost and benefits to the surrounding communities.

"We really want to go into this scientifically without biases, what does the science and what does the data show could be good areas and then, as well, what would the community impact be and what are their perspectives on this, as well," Fujii said. "So, both of those combined are going to be very important."

The feasibility assessment, Carswell notes, was just a first step.

"We plan to hold listening sessions to hear what people in different areas think about sea otter reintroduction, and we will hold stakeholder engagement sessions and have formal comment periods should we put forth a reintroduction proposal," she said. "We are especially interested in hearing from communities that are actively interested in the economic and other benefits sea otter reintroduction could bring."

Kimberly Wear (she/her) is the Journal's digital editor. Reach her at (707) 442-1300, extension 323, or kim@

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Kimberly Wear

Kimberly Wear is the assistant editor of the North Coast Journal.

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