SAVING OTTER 501 Goes Behind the Scenes at the Monterey Bay Aquarium, 10/16

California sea otters are struggling in the wild and no one quite knows why. Hunted to near extinction for their fur since the mid-18th Century, the hidden enclave of approximately 50 otters discovered near Big Sur in 1938 was a surprise to many along the California coast. The entire current population of about 2800 can trace their origins to that group of 50, but they all live in one small area which is a problem. One localized event, like an oil spill, could wipe them all out. That's why their status is listed as "threatened" under the Endangered Species Act.

It's not a rare occurrence to spot a newborn pup washed up on a local beach - hungry, lost and injured. But it may have a fighting chance thanks to a special team of marine biologists. Nature tells the story of the Monterey Bay Aquarium's 501st attempt to save a Stranded orphan otter and teach it to fend for itself in the wild when Saving Otter 501 airs on Wednesday, October 16, 2013 at 8 p.m. (ET) on PBS (check local listing). After the broadcast, each episode will be available for online streaming atpbs.org/nature.

Karl Mayer is the Animal Care Coordinator for the Sea Otter Research and Conservation (SORAC) program which operates out of the Monterey Bay Aquarium. He and his team are responsible for rescuing every abandoned or injured sea otter in northern California and bringing them back to the Aquarium's medical facility for evaluation. Those that can't be saved are euthanized, others may become part of aquarium exhibits elsewhere, but some are rehabilitated and released back into the wild.

A three-day old abandoned female pup arrives for an exam at the Aquarium, the 501st sea otter to be rescued since the rehabilitation program began in 1984. The team first tries to stabilize Otter 501 and then get her to begin accepting "otter milk formula" from a bottle. The concoction, developed by the team, is fed to her by handlers dressed in dark ponchos and welder's hoods. This "Darth Vader"-like disguise tries to mask the human form so the newborn doesn't become attached to them, even though they've taken on the role of otter mom. Otter 501 must also learn how to groom her fur as it will only keep her warm and dry when it's clean.

Once she can eat solid food; swim, rather than just float; and haul herself out of the water, Mayer decides 501 will be accepted into the surrogate program where she will raised by Toola, the Aquarium's original surrogate mother otter. In secret roof tanks atop the Aquarium, Toola teaches her young student a series of basic otter lessons: how to dive, how to find food, how to break open and eat whole clams and other shellfish, and how to handle crabs. Because they have no blubber, otters need a huge amount of food to maintain their body temperature in cold water. After five months of training, Otter 501 is returned to the wild in the hope that she has been provided with enough training to survive and have pups of her own.

The Aquarium is invested in saving and growing the sea otter population not just for the benefit of the otters themselves, but because they are a "keystone species" in the ecosystem. They eat the urchins that prey upon Monterey Bay's rich kelp forests. The kelp provides food and shelter to many animals, so keeping urchins in check is crucial. Without 501 and her species, the majestic kelp forests might one day disappear. But otter numbers have stalled. Scientists note some possible reasons: the rise in shark attacks, water pollution and parasitic infections from their food sources. Karl and his team continue their hard work, hoping to make a difference in a world where survival is a long shot at best.