A young New Zealand fur seal which stunned onlookers playing on the steps of the Sydney Opera House one year ago has bucked expert opinion and made the steps his permanent home.

The juvenile seal, believed to be about five years old, has been basking on the VIP steps at the Opera House since October 2, 2014.

NSW National Parks and Wildlife Service senior wildlife officer Geoff Ross said the seal's behaviour was an example of the health of the colony.

"What we are seeing with all the seals these days is a resumption of their traditional haul-out sites," Mr Ross said.

"The Opera House may not have been a traditional haunt for seals but certainly the rocks on the point there before the Opera House was built probably would have been in the 1800s."

The seal welcomes visitors to the Opera House VIP steps. ( 702 ABC Sydney: John Donegan )

The seal received a welcoming mention in the New South Wales Parliament soon after his arrival last year.

"On behalf of the New South Wales Parliament, I welcome the Sydney Opera House seal to Sydney Harbour and look forward to its continued presence over many years to come," parliamentarian Peter Phelps said in a motion put to the House.

Wildlife officers barricaded off the area when the seal was first spotted and, while the barricades remain, spectators are able to enjoy an uninterrupted view of the animal.

"The fact that we've built a city on the edge of their natural haunts doesn't bother them at all," Mr Ross said.

Mr Ross said the health of the seal was also a positive reflection on the water quality of Sydney Harbour.

"That improvement in water quality encourages more fish stocks and that encourages predators, so along come all your seals," he said.

Geoff Ross is encouraged by the way Sydneysiders are adaptive to wildlife, but warns visitors to observe from a distance. ( 702 ABC Sydney: John Donegan )

"I love the way Sydneysiders are very adaptive to wildlife," he said, pointing out that the seal would welcome other seals into the area.

"Seals are really social animals and in years to come we might see more seals there."

Mr Ross said he was encouraged by the length of time the seal had stayed so far and that it reflected well on modern human interactions with wildlife.

But he warned people to observe the seal from a safe distance when visiting the Opera House.

"They can move quickly and they will defend themselves aggressively," he said.

"They can inflict a serious bite and those bites can become infected, so don't jump fences and try to pat them."

Fur seals making a recovery after near-extinction

Hunting in the 1800s took both New Zealand and Australian fur seals to the brink of extinction, but there has been an encouraging rise in numbers over the past decade.

"New Zealand fur seals are recovering more rapidly then their Australian cousins," Mr Ross said.

"Before sealing in Australia, fur seals were very, very common in and around the harbour.

"With the advent of sealing we stopped seeing them come into their usual haunts, and for me it is exciting to see animals returning to their natural haunts."