IT'S been a whale of a season along the Great Ocean Road and it seems there will be more to come. Visits by southern right whales to areas stretching from Barwon Heads to Portland have been the best since records were first taken 20 years ago.

At Warrnambool's Logans Beach where the average number of whales at any one time has been two officials spotted 21 mothers and calves on a single day.

Mandy Watson, senior biodiversity officer and southern right whale researcher for the Department of Sustainability and Environment, has been researching the whales since 1995 and says she's still "coming down from a high" after the recent sightings.

She has a lot of work in front of her now determining why numbers have suddenly increased.

"No one knows what caused it. They may have come from other locations; that's the most likely scenario," Ms Watson said.

"In the past few years at the head of the bight and along the West Australian coast the numbers have been increasing by 7 or 8 per cent per annum but in this region it's been fairly stable for 20 years.

"They were almost whaled to extinction and perhaps it's taken them longer to recover. This year, though, we saw a few extra whales with calves and lots of single whales, which we've never seen before.

"There was a lot of calving and also a lot of mating activity with usually two males for every female and then it takes three years before a calf is born."

Ms Watson said there were still many mysteries to solve.

"With their migration from sub-Antarctic waters we're not sure of their route," she said.

"We don't know their paths but they usually arrive on the far-south coast in June. Normally, they like to use big sheltered bays such as Port Fairy and Portland."

DSE hopes the whales will now develop an affinity for the area.

"Calves tend to return to the place they were born," Ms Watson said.

Story from Geelong Advertiser