Tiny Refuge Fueled Sea Otters’ Incredible Rebound
Halfway down the coast of Monterey Bay, travelers on California’s Highway 1 cross a nondescript bridge over a muddy estuary. Smokestacks from a power plant loom over eroded riverbanks. A few fishermen perch on a dock, dipping their poles into the murky water.
If you never hop out of your car, you might not ever appreciate what a special place you’re in. But take a moment to explore and you’re certain to see a sea otter, adorable evidence of one of the most incredible recoveries in ecological history. Elkhorn Slough (pronounced “slew”) is California’s largest estuary and is home to so many otters, it’s reached “maximum sea otter carrying capacity,” according to the Monterey Bay Aquarium.
Take a kayak through the slough’s lazy waters and you’ll see dozens of shiny otters floating, spinning, and diving for the long red mudflat worms they devour like tasty hot dogs. Seals sleep on the protected shores while egrets stand frozen, glaring at you, and sandpipers peck in frenzied groups.
In the early months of the year, the slough is a favorite refuge for mother sea otters, who float with their newborns asleep on their bellies in the calm and predator-free waters. Their habit of holding their paws in the air like they’re waving at passersby will make most observers instant fans.
“Like pandas, sea otters are enchanting creatures,” Professor Isabel Abbott told the authors of The Death & Life of Monterey Bay (2011, Island Press) by Steven R. Palumbi and Carolyn Sotka. This short book recounts the journey of the California sea otter, its benefits to the entire Monterey Bay ecosystem, and the one marine refuge that made a pivotal difference in its survival.
Long before the Endangered Species Act of 1973, and long before Elkhorn Slough became a State Marine Preserve, the tiny town of Pacific Grove, 20 miles south of the slough, made the bold move to protect just 11 acres of shoreline. In 1932, it established the Hopkins Marine Life Refuge. Perched at the southern tip of Monterey Bay, the refuge simply prohibited people from harvesting invertebrates. Yes, we’re talking sea slugs and shellfish.
The California sea otters’ recovery from near extinction is well documented. However, this one small piece of legislation that enabled their rebound is rarely mentioned. In fact, it not only helped save the sea otter, but it also created ripple effects that spread hundreds of miles and persist to this day.
Hunted nearly to extinction
As recently as the 1960s, there weren’t any sea otters living in all of Monterey Bay. Now, almost 3,000 of them thrive there and roam as far south as Santa Barbara.
To understand the California sea otters’ recent plight , let’s take one of these mother otters and call her Dora. Let’s rewind 100 years and move an hour south. Dora is hiding out with 50 other otters under the deathly steep cliffs of Big Sur, taking refuge from sharks in small coves, the same hideouts that allowed her species to escape fur traders in the previous century. No one knows Dora is there. They think sea otters are extinct. After all, no one has seen a sea otter in California since its fur trade collapsed in 1850.
Dora is ravenous. She’s got to eat a quarter of her body weight, or about 15-20 pounds of shellfish, per day to stay healthy. But she has a hard time finding enough food, like urchins and abalone, to feed herself and her pup. Little does she know, but Dora’s got a friend in an enigmatic marine biologist named Julia Platt.
Personal vendetta turned ecosystem cascade
Julia couldn’t stand that Ed Ricketts, a friend of John Steinbeck and the inspiration for the character Doc in Cannery Row, was harvesting critters along the shoreline in front of her Pacific Grove home. Ricketts was gathering starfish, urchins and sea slugs and selling them to science classrooms across the country.
Meanwhile, Monterey Bay was a mess. Canneries were dumping 100,000 pounds of fish guts into the water every day, suffocating sea life and sending a stench up and down the coast. Whales had been hunted to near extinction. Seals were gone. The sardine fishery was collapsing. Seeing this devastation, in hopes of preserving some safe spawning grounds for marine invertebrates, Julia became determined to set aside those wee 11 acres that no one could touch.
But establishing the refuge was no easy feat. Only the State of California maintains jurisdiction over coastline. Undeterred, as mayor of Pacific Grove, Julia petitioned the state to grant an exception. The California State Legislature agreed in 1931 to allow Pacific Grove to police the shoreline, the only time it’s ever done so.
The refuge prohibited harvesting any marine invertebrates, including abalone and urchins, favorite foods of Dora the sea otter. Julia’s thinking was that if one small piece of ocean could be reserved as a sort of seedbank, it could continuously regenerate the overexploited areas around it. “Tiny larvae may swim or be carried by currents to all points along the shore …” (page 84).
Abalone soon grew abundantly at the refuge. Mussels crowded up the shore. Urchins filled the seabed. Meanwhile, Dora and her crew, descendants of the only otters that escaped fur traders at Big Sur, remained hidden from the public eye. People in Pacific Grove were thinking of sea slugs, not sea otters, when they created their marine refuge.
Then, in 1938, sightseers rediscovered otters at Big Sur.
It took more than two decades, but because Dora’s progeny are voracious abalone hunters, they found Julia’s Hopkins Marine Life Refuge.
“Even the earliest otter watchers realized that these quick and charming animals moved like a plague of locusts across the landscape, depleting resources in an area and then moving on. So it was no surprise that the first otters to round Point Pinos and enter Monterey Bay were a few young males, who turned the corner of California history in 1962.” (page 128)
By April, 1963, a raft of 75 sea otters was living in the Hopkins Marine Life Refuge.
The magical part comes when, because the canneries have stopped polluting the bay and the otters are bringing the abalone and urchin numbers under control, giant kelp forests regrow, creating 100-foot-tall curtains of protection from sharks for seals, fish, octopus and, of course, otters.
A keystone species
An ecological cascade followed. Turns out, sea otters are a keystone species, which means their presence is a foundational cornerstone of their ecosystem. Without them, the ecosystem collapses. With them, the ecosystem expands.
Most importantly, by eating urchin and abalone, otters ensure their own habitat, giant kelp forests, thrive.
Sixty years later, Monterey Bay is filled with kelp forests and sea otters. Now, the Monterey Bay National Marine Sanctuary, created in 1992, stretches 276 miles north to south, and is a home or passthrough point for hundreds of species, including humpback and blue whales, dolphins, harbor and elephant seals, seabass, anchovies, and many sea birds. Agricultural lands abutting Elkhorn Slough have been converted to a state wildlife area.
“The reconstruction of an ecosystem, link by ecological link, is seldom seen in the modern environmental narrative,” Palumbi and Sotka write. “Julia’s protected areas may have been one of the catalysts for such a construction cascade in Monterey Bay, although many other elements also had to fall into place.” (page 137)
What now?
Marine ecosystems and kelp forests north of Monterey Bay up to the California/Oregon border are suffering from an overabundance of purple sea urchins. However, a bottleneck of sharks roaming the coastline at Año Nuevo State Park keeps otters from migrating north into more of their historic range. The sharks lurk year-round near the elephant seal colony that calls the beaches of Año Nuevo home. Conservationists have long discussed transplanting otters further north, but so far, no efforts have succeeded.
Another threat is toxoplasmosis, a parasite carried by domestic cats, mountain lions and feral hogs. Toxoplasmosis, which washes into the slough and bay through feces, doesn’t harm carrier animals like cats, but has proven lethal to sea otters.
A little policy with big impact
The International Fur Seal Treaty prohibited the hunting of sea otters in 1911, long after they were considered extinct in California. It might have been too little too late but for the coves of Big Sur. But sea otters were stuck those coves for almost 100 years, with limited shelter and food. What would have happened if they’d never had a chance to eat some abalone at the Hopkins Marine Life Refuge?
In this one instance, a tiny town, a determined woman, and a marine refuge made all the difference in allowing a species and an ecosystem to bounce back.
It goes to show, a little policy can go a long way.
Quick facts:
Giant kelp can grow 18 inches per day.
The main food of urchins and abalone is kelp.
One sea otter consumes 15-20 pounds of kelp-eating shellfish per day.
Before baby sea otters have enough buoyancy to float, their mothers wrap them in kelp to keep them afloat so they can continue diving, foraging and maintaining their calorie consumption.
Sea otters, unlike other marine mammals, do not have blubber. They keep warm through their thick fur and constant movement, which requires calories.
An entire cat’s body fur can fit into the space of one square inch of sea otter fur.
The California sea otter, also known as the southern sea otter, is a subspecies of that inhabits the central California coast. It is smaller than the northern sea otter, which historically roamed the Pacific from the Oregon coast up through Washington, Alaska, the Aleutian Islands and then west all the way to Japan.
Further reading:
Why Are Sea Urchins So Destructive to Kelp Forests?
A history of the Monterey Bay Aquarian Sea Otter Program
Sea Otters Killed by Unusual Parasite Strain
North Coast officials, scientists and stakeholders launch exploration of sea otters’ return
Sea Otters Are Walled in by Hungry Sharks
Julia Platt, mayor of Pacific Grove, 1932-1935:
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