Chapter 9: A Wild Sea Otter

“501 will never understand that what started out as a dire misfortune—to be orphaned and a few hours from death—was counterbalanced by an incredible stroke of luck.”

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Typically SORAC monitored 501, along with the other surrogate-reared sea otters in Elkhorn Slough, about once a week. They record information such as her exact location, whether she is in a group with other otters, and her behavior. In addition, if she is foraging, they collect data on how successful she is at finding food and what she is eating.

Cruising slowly down the slough, they listened for the signals from 501’s transmitter. Hearing it they would hone in on her location. A visual on her flipper tags confirmed her identity.

Learn more about how 501 is adapting to life in the wild

Otter 501 eventually integrated with the group of females and pups she had first been attracted to on the third day of her final release. This group of resident females often rafted up together, using the eelgrass outside the main channel as anchorage. She adopted many of their same behavior patterns, rafting as well as roaming, foraging, and resting in the same creeks and side channels. 

501 continued to improve her foraging skills and caught prey just like the other otters. In particular, 501 began to focus foraging efforts on larger clams: prey items that require special skills to capture and consume. Though harder to catch, these clams provide more energy than smaller, easy to find prey, which is a benefit for an otter struggling to survive.

See some of what 501 is eating in the slough

“There’ll be a foraging bout where they might do seven to ten dives where they’re obviously digging for clams,” said Karl Mayer. “They may eat two or three clams during those seven to ten dives, and then they’ll switch and start eating some smaller crabs.”

Despite her overwhelmingly positive progress, not all the news about 501 was good. At the age of two years and three months, over a year since her release, 501 was believed to have had her first pup. “She had a pup that was most likely a stillborn,” Mayer said. “It was extremely small. I think it was too small to have been a full-term pup.”

Otter 501 was the sixth surrogate-reared female to reach sexual maturity. As of October 11th, 2012, five of the six were known to have given birth in the wild. 501 was the youngest of them to have a pup of her own.

Sadly, it is fairly common for first-time sea otter moms to have pups that don’t survive. Studies show that only 30 to 50% of first-time mothers successfully raise their pups to an age where they can be weaned. Those are not very high odds.

However, with age comes better reproductive success. So by five or six years old, sea otter moms become relatively successful, and SORAC caretakers hope that 501, ever the precocious learner, will follow the same pattern. 

What you can do to keep sea otters safe

Otter 501 continued to thrive in Elkhorn Slough.

“Were it not for her flipper tags she would be indistinguishable from the wild females that are part of that group,” said Mayer. Anonymity is one of the greatest signs of success.

It is a far different life for 501 now, compared to her time at The Monterey Bay Aquarium—even compared to what her life would have been had she had the chance to stay with her birth mother.

Elkhorn Slough was a much tamer place than Cayucos, with its rough, open ocean and great white shark patrolled waters.

Even within the safe haven of the slough, 501 still faces constant threats. The slough, which drains vast agricultural lands, is subject to pollution, competition for food, and common disturbances from human visitors. Life is not easy living in a world so close to people.

Learn about sea otters relocated to San Nicolas Island

As a healthy adult, 501′s growth will flatten out to a little more than 20 kilograms (44 pounds), she will consume around 5 kilograms of seafood a day, and maintain an important role in her surrounding ecosystem.

As a wild sea otter back in nature, 501 may have one pup per year for the rest of her life. In only a few years, her wild pups may even start having wild pups of their own.

501 will never understand that what started out as a dire misfortune—to be orphaned and a few hours from death—was counterbalanced by an incredible stroke of luck. She made it to dedicated people whose ingenuity gave her Toola, an animal who represented the best shot 501 had at survival in the wild after such a desperate start.

Will the mystery of what happened to 501's birth mom ever be solved?

Through all the sub-Q injections, pokes and probes, Darth Vader encounters, nettings, mixings, and separations, 501 could hardly thank these people. But their sheltering, coddling, and loving administrations of mothers milk substitute would be rewarded by something far better than a thank-you. In the end, 501 gave back as much as she received.

The exchange was simple. 501’s life was a success story amidst an at-risk population of animals with precious few answers to their problems. 501 taught her rescuers what it takes to do it right. Through her success, she helped them find answers that might benefit the entire southern sea otter population. For those who rooted and cared for 501, there can be no better gift.

Success stories like 501’s stand between the potentially catastrophic threats facing sea otters and the looming specter of extinction her caretakers strive to prevent.

The rescued now becomes a rescuer.



back forward

Pay it forward.

Commit to one action that will help sea otters and share Otter 501’s story with your friends and family.

Use this super simple editor to create a video about Otter 501. Explain the action you will take to help sea otters. Then, tell your friends! Share your video on Facebook, Twitter (link to Otter 501 FB and twitter) and E-mail.

 Visit the BLUE Ocean Film and Conservation Event website if you are interested in making a difference for the ocean through film.

On To Chapter 8 « Return to Slideshow

Special Features

This Page All
  • AAS: MS Wild 501

    Ask a Scientist: Michelle Staedler – Otter 501 in Elkhorn SloughLearn more about how 501 is adapting to life in the wild

  • Keep Otters Safe

    Keep Otters SafeWhat you can do to keep sea otters safe

  • Mini Doc: San Nic

    Mini Doc: San Nicolas IslandLearn about sea otters relocated to San Nicolas Island

  • Mystery of Mom

    Mystery of MomWill the mystery of what happened to 501's birth mom ever be solved?

Chapter 1: The Ocean is Cold but Mom is Warm

Chapter 2: Less than Ideal Rescue

Chapter 3: Emergency Treatment

Chapter 4: Species in Danger

Chapter 5: No Substitute for Mom’s Cooking

Chapter 6: The Surrogate

Chapter 7: Furry New Friends

Chapter 8: Release

Chapter 9: A Wild Sea Otter

Ask a Scientist: Michelle Staedler – Otter 501 in Elkhorn Slough

What are the sea otters in the large raft at the mouth of Elkhorn Slough?

Michelle Staedler: The raft of otters in Moss Landing Harbor jetty, sometimes referred to as “The Boy’s Club”, tends to be made up of sub-adult males, young males, and older males. Occasionally, you have a few females that poke their heads in there and hang out. Up in the Elkhorn Slough, you have more of a territorial situation, similar to what you see along coastal California areas where there’s one male that might be overseeing a certain area. In the Slough, there may be two or three territorial males, one for sure is at Sea Bend.

501 rafts up with a group of females inside the slough. Does she have a specific territory?

MS: 501 has a home range but not a territory. Adult males hold territories where they cover a certain segment of nearshore waters. In general, around the Monterey Peninsula, it’s about a kilometer in length along the coast. Females, however, can travel between different males’ territories.

In the Slough, where 501 lives, she and other females may swim to different locations within the Slough for resting and feeding. One day, 501 may be up in the east end by Five Fingers and on another day she may be over by Seal Bend. She and others may even leave the Slough and swim offshore to find food.

Would you be able to tell 501 from a wild sea otter?

MS: For the most part, she would look like a wild otter. One of the things that animals raised in the tanks tend to do when they’re cracking prey open is pick up a hard-shelled prey item and crack it on the side of an emergent rock, or on the side of a dock or a boat—for those living in a harbor—rather than on a rock on their chests. So, if you see an otter in the slough that might be cracking a clam or a mussel on someone’s kayak, or someone’s boat, then they’re more likely to be a rehab otter. However, I wouldn’t say 100%, necessarily, because many of the ones raised in the harbor do the same thing; it’s something they’ve learned from their moms. The otters along the coast don’t necessarily swim over to an emergent rock, and crack a prey item on it. They may use a tool on their chest to break open a snail.

How is 501 fitting in with the other sea otters?

MS: She is integrating nicely back into the rest of the population. She has many of the same challenges as recently weaned wild otter pups. 501 will be doing the same things her cohorts do as she matures. Around age three she will start mating, will have the same possible nose wounds and injuries from mating as other females, and six months after mating she will have her first pup. Sometimes first-time moms aren’t successful with their first pups, but there are always exceptions. If all goes well for 501, she will live to be around 15 or so years, and have a new pup each year.

501 Eating Different Prey

Keep Otters Safe

This startling photograph shows a sea otter pup trapped in a plastic bag as its mother desperately tries to free it. The choices people make, such as whether to use disposable plastic or reusable goods, and whether to recycle or litter, have huge impacts. Okeanis, a marine mammal research group from Moss Landing, California, put together this wonderful list of actions you can take to help protect not just sea otters and other marine mammals but all kinds of animal and plant life.

Eliminate single use plastics. 80% of plastic marine debris originates on land. Otters and other marine animals get entangled or ingest plastic and die. Use reusable shopping bags, water bottles, coffee cups, and utensils instead of disposables.
Cut beverage six pack plastic rings apart before throwing them away. Marine animals can get caught in the rings if they end up in the ocean.
Avoid releasing helium balloons into the sky as they often end up in bodies of water.
If you are a recreational kayaker or boater, give otters plenty of space. If you startle them and cause them to dive, you might separate a pup from its mom as well as cause them to expend energy that should be reserved for survival activities.
Make sure your car is not leaking oil. Oil down the storm drain gets into the ocean and could affect an otter’s ability to stay warm.
Never touch or move an injured, sick, or stranded marine animal. Report it to the Marine Mammal Center at 831.633.6298.
Reduce or eliminate your use of herbicides, pesticides, oil, and other toxins. They flow into the ocean via storm drains and waterways in your neighborhood.
All hazardous materials should be disposed of properly. Check with your landfill – most have a place to drop them off. Never put toxic substances down the drain.
Dispose of cat litter in the trash can rather than flushing it down the toilet. Cat feces can carry bacteria and harmful disease.
Buy organic produce. Support farmers who do not pollute the environment.
Dispose of fishing lines, lures, and nets properly to help keep them out of the ocean as marine animals can mistake them for food or become entangled in them.
Check the box on your California tax form to donate to sea otter conservation.
Tell your representatives that you care about our ecosystems and urge them to do the same.
Donate to organizations that support sea otter research.

Mini Doc: San Nicolas Island

Learn more about the controversial project to relocate a population of sea otters to a San Nicolas Island, a remote island off the southern California Coast.

Mystery of Mom

Otter 501 is no longer a pup requiring her mother. With the help of Toola, 501 now survives on her own and can even have pups herself. But what happened to 501’s birth mom?

A little forensic detective work could help unravel some of the mystery.

Over the years scientists have been collecting DNA, for possible future use, from sea otters that have stranded or were part of tracking studies.

One day, a genealogy study might come up with a record from a database that matches 501’s DNA. Maybe her mother or a sibling? An older sibling would have, of course, been born before 501. But if a younger sibling was found, then that would prove 501’s mom was still alive long enough after their separation to have had at least one other pup.

What if the match is not with some old DNA record, but with a DNA sample from a living sea otter? Could 501’s mom still be alive?