Queensland researchers say whale watchers have reported fewer sightings this east coast migration season.
The east coast of Australia is known as the "humpback highway" during winter and spring as whales migrate north to breed.
But experts say there has been less traffic near popular beaches this year.
Griffith Centre for Coastal Management researcher Dr Olaf Meynecke said it's been an unusual season with whales remaining further out to sea.
"Very different to the last three years at least, because we've had the whales migrate quite far offshore," Dr Meynecke said.
"There's a lot less happening closer to the coast."
Fewer entanglements in shark nets
Dr Meynecke said the southern migration was now underway, with whales and their calves making their return journey.
He said pods had been more commonly spotted 10-to-15 km offshore.
"We've actually had less entanglements in shark nets and those entanglements usually happen when the whales are close to shore," he said.
"Of course the mums and calves usually come close to shore to rest.
"But there's not as many as we had last year and definitely not as many newborns.
"It's been a very different season."
Are whales looking for Nemo?
Dr Maynecke said the East Australian Current (EAC) - made famous by a certain clownfish - serves as a navigation tool for migrating humpbacks.
He said this year the EAC was further offshore which could explain why whales were too.
Ocean Analyst Lucinda Matthews from the Bureau of Meteorology said the EAC did appear to weaken along the Gold Coast in August and move slightly east.
"It's possible the whales are now staying offshore to stay in the maximum current available to hitch the best ride south," Ms Matthews said.
The EAC carries warm water southward from the tropics.
"This is significantly warmer water compared to what you'd find at the latitude of Sydney, for example," Ms Matthews said.
"It's quite nutritionally poor itself but the current flow generates ocean eddies and creates conditions which boosts the water productivity further south."
Interaction between the coast, the current and northerly winds can generate upwelling which brings deep, cold and nutrient dense water to the surface.
These conditions can provide feeding opportunities for migrating whales.
"Without bringing nutrition itself, it (the EAC) helps to pull up nutrition from where it wouldn't come otherwise," Ms Matthews said.
"If you didn't have those northerly winds, you still get sharp temperature gradients just from having that warm current flowing into cooler surrounding waters.
"Those thermal fronts and the current-driven mixing are also very active in a biological sense."
'Close encounters' with boats
Seaworld Cruises estimated 35,000 humpback whales had migrated this season.
Group brand manager Lauren Horner said her boat crews had experienced a similar number of whale encounters to previous years.
"What we tend to see around this time of the year is all of those mums and their new little bubs come into the bay," Ms Horner said.
"They'll generally hang around for four to seven days at a time.
"You see all these really close encounters with the vessels.
"You'll watch mum breech and then you watch the babies practice and copy after her. It's really cute."
Despite the lack of interstate tourists and changes to the whale migration route this year, tour operators are hopeful of a bumper school holiday period.
"We are missing our Sydney and Melbourne guests; we would love to be welcoming them here," Ms Horner said.
"But we do sort of see a strong uptake in the local market."
Hopefully they see a lot more whales too.
© ABC 2021
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