It's been a bumper baby season off Victoria's south-western coastline, with a fourth southern right whale calf born at the traditional whale nursery at Warrnambool.

While it's good news, there's still a long way to go before the mammal can be taken off the critically endangered list — with an estimated 3,500 left worldwide.

There were concerns last year when no females returned on their three-year breeding cycle to calve at Warrnambool's Logans Beach, but the sight of a fourth calf frolicking with its mother has renewed confidence for the future of the species.

"This year, they've really made up for it," Department of Environment, Land, Water and Planning senior biodiversity officer Mandy Watson said.

The last big calving season was in 2013. The record number of calves born at Logans Beach is six baby whales in 2009.

Southern right whale populations were nearly wiped out by extensive whaling in the 1800s. The species is prized for its blubber and baleen.

People have been urged to keep their distance from the whales. ( Supplied: Chris Farrell )

About 300 individual whales are now found around the south east of Australia, compared to a population of up to 30,000 humpback whales on both the east and west coasts.

Small groups have also been spotted at other locations along the coast including Portland, Port Fairy and Western Port Bay.

"We've got a really small population compared to humpback whales, so they've got a really long way to go before they're recovered from commercial whaling," Ms Watson said.

"There would have been tens of thousands of these whales historically before they were hunted, so we're really a long way from that."

'Keep drones away from whales'

Researchers are conducting a crowd-sourced identification program for the southern right whale population.

"We can track individual whales because of the pattern of skin markings on their heads and every individual whale is born with its own unique pattern," Ms Watson said.

Southern right whales have a three-year breeding cycle. ( Supplied: Chris Farrell )

"We can photograph them and we use those images of the head to track individuals and I have a catalogue of about 300 whales."

But officials are warning people not to get too close, with fines being issued for people flying drones within 500 metres of the whales.

The buzzing from drone motors has the potential to cause distress to noise-sensitive whales.

Capturing images of the whales and their calves has become a labour of love for Chris Farrell.

Southern right whales were almost wiped out from whaling. ( Supplied: Chris Farrell )

He has thousands of aerial photographs, using a long telephoto lens to capture the magnificent mammals from a fixed-wing aircraft at a safe distance so as not to disturb the whales.

"When you're in the plane, I can see everything that's going on," Mr Farrell said.

"I'm witnessing their private life … when you see the calves playing with their mothers, they're actually quite relaxed.

"It's not work, it is a passion and I want to help with such a critically endangered species."