THERE'S a new kid on the Port River block and he or she is a cutie.

The newborn bottlenose dolphin, whose gender is not yet known, will be called "Baby" until the Whale and Dolphin Conservation Society's managing director, Dr Mike Bossley, chooses a name.

The bundle of joy was spotted off Garden Island by excited Adelaide Dolphin Sanctuary volunteers at 7am yesterday.

Volunteer Barb Saberton, 44, from Salisbury, captured the moment in this picture.

"We saw a little splash which turned out to be a gorgeous, brand new baby," she said.

The baby, believed to be little more than 24 hours old, remains under the watchful eye of mother Bianca.

"The baby doesn't know where its blowhole is yet so lifts his body right out of the water to breathe," Ms Saberton said.

"It was especially exciting because I was there four years ago when Bianca had her last baby, Hope.

"Bianca looked fabulous and was doing such a good job of moving the baby away when boats came around."

The Port River is home to about 50 permanent dolphin residents.

There is a strict no-approach zone restriction within 150m of a baby dolphin.