Staff say the bond formed quickly, with Rey grooming, foraging and teaching skills Sunny needs; neither otter can return to the wild because both are too habituated to people.
Run with Monterey Bay Aquarium, the programme has rehabilitated and released nine otters, helping a federally threatened California southern sea otter population that has recovered to about 3,000.
Why are some rescued sea otters deemed 'unreleasable' and fated to a life in captivity?
What is the hidden cost to our oceans if this keystone species isn't saved?
With a petition to remove their protections, can saving individual pups still save the species?