Five pups have now been born in the wild to otters raised by surrogates at the aquarium and then released.
"These births and the successful weaning of pups in the world by surrogate-reared individuals is significant because it indicates that these sea otters are not only surviving following release, but also contributing reproductively to the wild population," said the aquarium's Animal Care Coordinator Karl Mayer. "This is the benchmark of successful rehabilitation and reintroduction efforts."
Both adult otters are almost 5 years old and gave birth near Moss Landing, according to the aquarium.
Sixty percent of surrogate-reared pups have survived a minimum of one year after release, compared to less than 30 percent survival for pups reared exclusively by people, aquarium officials said.
Mayer said he and other staff will continue to monitor both pairs of mothers and pups regularly.