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Sea Otter Savvy

Sea Otter Science And Community Outreach

What are we missing?

Have you ever wondered why you don’t see sea otters in San Francisco Bay or off northern California shores? Truth is, sea otters did inhabit the San Francisco Bay, and their historic range did continue north to Alaska and over to Japan and Russia. In the early 1700s the worldwide sea otter population was estimated to be between 150,000 to 300,000 individuals. However, due to the maritime fur trade the sea otter population was decimated. By 1911, when sea otters were protected under the International Fur Seal Treaty, there were fewer than 2,000 individuals that remained across 13 different colonies - the once continuous population was broken. A small remnant of the southernmost colony survived, hidden off the Big Sur coastline, and our current population of the southern (or California) sea otters are all descendants from these few survivors. The current range of the southern sea otter (now recognized as a distinct subspecies from northern sea otters) is from Gaviota near Santa Barbara up to Pigeon Point near Año Nuevo State Park. Despite protections through the Endangered Species Act and the Marine Mammal Protection Act, the southern sea otter range has expanded slowly and currently further expansion is met with challenges. 

For more detailed information on sea otter natural history and range click here


Why is range expansion so slow?
After a population has been fragmented for so long, range expansion can be complex. Sea otter research and conservation only began in the mid to late 1900s. Understanding how coastal communities have changed with the removal of sea otters, and how sea otters influence their ecosystem, has developed over time through many studies. We have learned that female sea otters are largely site-specific with the costs and risks of motherhood keeping them close to familiar foraging areas. They also prefer areas with kelp (if in open water) or eel grass (if in estuaries) for security and protection. Unfortunately, since northern California waters are missing sea otters, the ecological balance has shifted, and both kelp and eelgrass habitats are at risk. A lack of protective kelp canopy  also makes sea otters more susceptible to predation from white sharks. All of these factors may be limiting how quickly the southern sea otter population can expand into new areas.

How might sea otters impact the San Francisco Bay Area and Northern California ?

Sea otters are a keystone species, meaning they greatly influence their ecological community. Maintaining body temperature in the cold waters of the Pacific Ocean requires a high metabolism and they must eat over ¼ of their body weight every day. This large appetite means they consume a lot of invertebrates (animals without spines) that would be grazing on kelp and eelgrass. This population control over certain species, like sea urchins or crabs, allows the kelp forests and eelgrass beds to thrive, providing sanctuary to hundreds of other species. You could say sea otters are ecosystem superheroes – promoting a diverse coastal community. If sea otters were to return, there is the potential for eelgrass bed restoration in San Francisco Bay and increased kelp forests along northern California’s coast. Both of these would promote an increase in biodiversity which can lead to healthier fisheries. Though sea otters do eat some seafood we like to eat, studies suggest that in time even these populations may benefit in the long run. A recent study has also shown how sea otters can financially benefit communities.

Where would sea otters go?

Despite the complications in range expansion, sea otters may still slowly extend their range naturally. In this case, it is likely they would end up in San Francisco Bay and cross to Marin county in time. Where specifically they end up would depend on a balance of prey availability, habitat suitability, and type and magnitude of threats. If sea otters are considered for reintroduction, through human assistance, these locations would be extensively reviewed and chosen based on research that investigates habitat suitability, prey availability, and risks from human impacts (pollution, boat traffic etc.).

learn about Dr. Brent Hughes research on how San Francisco Bay could increase the California sea otter population here.


What can we do?

The best way to support sea otters is to remain informed on how the California sea otter population is doing. Your awareness and understanding allows you to share this information with others and use your voice. Sea otters, like all the natural resources and wildlife in the United States, are considered a public trust. This means the government manages and protects these resources to benefit you. Therefore, your voice and opinions matter – the public ultimately decides the fate of sea otters. So, if you are wondering what you personally can do, you can: learn about sea otters, spread this knowledge with others, share your opinions with your representatives, and support research and conservation efforts.

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