Doc, alongside wildlife volunteer organisations and the New Zealand Sea Lion Trust, are searching for Mahira, a 5-year-old female sea lion, or pakake, who has not been seen since Saturday.
Officials have told the public not to approach or disturb any pakake to get an identification, and to keep at least 10m from them at all times.
Acting Coastal Otago operations manager Samantha Marsh said the rangers had assessed the condition of Mahira’s unnamed 3-month-old pup and were regularly monitoring it.
The female pup was born in the Dunedin city area and Mahira had successfully moved it to a pakake creche site on the Otago Peninsula.
Trust volunteers first raised concerns with Doc on Saturday, who co-ordinated searches at the weekend.
"Ōtākou rūnaka have been informed of the situation," Ms Marsh said.
Pakake mothers leave pups and embark on feeding trips a week after giving birth.
Three-month-old pups were often left alone for longer periods, depending on their mother’s ability to find food.
However, pups were reliant on their mothers for all nutritional requirements and would not start feeding on solid food until about 9 months old.
"We have had instances in the past where female pakake have been separated from their pup," Ms Marsh said.
"Once the mums were located, Doc staff reunited their pups with them successfully."
Doc would not release the pup’s exact location as it did not want people seeking her out, she said.
An email from Doc posted by a Dunedin wildlife group described Mahira as a small female sea lion with a pink tag in her right flipper and a hole in her left flipper.
The public should call the Doc emergency hotline (0800362-468) if they saw a sea lion severely injured, entangled in marine debris or being harassed by people or dogs.
