Endangered Australian sea lion pup born at Taronga

Taronga Zoo has announced the first birth of an endangered Australian sea lion pup from wild-born parents in eight years, saying it has injected critical genetic diversity into the captive insurance population.

The female pup was born on January 31 from mother Tarni, who was found orphaned in 2017 on the Great Australian Bight’s Baird Beach when she was one year old. Her mother left for the sea and didn’t return.

The birth of the baby sea lion in January has been announced on International Seal Day.Credit: Taronga Zoo

Now the zoo has bred Tarni with a male also rescued from the wild, 19-year-old Charlie. It’s Tarni’s first pup and Charlie’s fourth. After she gave birth it took a few tense days for Tarni’s maternal instinct to kick in, but she soon began nursing the pup, who’s yet to be named.

“This birth is a massive win to the regional breeding program conserving endangered Australian sea lions, as Tarni’s wild genetics are an important boost to the genetically robust zoo-bred population,” said senior marine keeper Lindsay Wright on Saturday.

The pup has doubled in weight from seven to 14 kilograms and is living in a behind-the-scenes nursery, learning to swim in a three-metre deep pool and hold her breath for longer intervals (she’s up to a minute).

“Her diving and her breath-holding is advancing every day in leaps and bounds,” marine mammal keeper Michelle Simpson said. “I think she’ll be hopefully out in the big exhibit pool in no time.”

Australian sea lions are only species of their kind, including seals, that are endemic to Australia. They’re one of the rarest pinnipeds in the world, with only 6500 adults left in the wild.

Newborns are precious. Taronga is one of two places that breed the marine predator. “Pups are quite rare because seal lions have an 18-month gestation period,” Simpson says. “It takes a lot longer than other seal species to produce a puppy.”

Conservation in the wild is further complicated by the fact sea lions return to the same spot they were born to give birth, a behaviour known as “philopatry”.

The 14 kilogram pup is learning to swim and hold her breath.Credit: Taronga Zoo

That means each colony of sea lions is effectively closed because they don’t tend to interbreed with other colonies, risking genetic bottlenecks.

Colonies can vanish if just a few adult females die.

“Australian sea lions are incredibly inquisitive and really playful, and so it’s not uncommon they find gill nets and tear them, rip them, play with them, and they quite easily become entangled,” Simpson said.

One third of the pups die before they’re weaned, many crushed by brawling young males.

A raft of universities has joined forces under a grant from the government’s Saving Native Species program to study human-made dangers to sea lions, which includes PFAS, extreme heat and toxoplasmosis injection via cat faeces sweeping into the ocean.

March 22 marks International Seal Day.

The Examine newsletter explains and analyses science with a rigorous focus on the evidence. Sign up to get it each week.