University of NSW academics believe that the tourism drawcard could actually deplete the whales after collecting and analysing samples of whale blow, which is comparable to human nasal mucus.

The researchers found "significantly less microbial diversity and richness on the return leg of the whales migration", a potential sign that the giants of the sea were less healthy than when they were heading north.

Dr Catharina Vendl, the lead author of the study published in journal Scientific Reports this week, provided the first evidence that the microbial readings could indicate the overall health of whales.

"The physical strains of the humpbacks migration likely affected the microbial communities in the whales airways so, our findings are key to further developing the analysis of airway microbiota as a non-invasive method for monitoring the immune function and overall health of whales and dolphins," Dr Vendl said.

"People enjoy whale-watching season, but with it comes reports of whales becoming stranded. Although humpback whale stranding events occur naturally and regularly to injured and young whales, it is crucial to monitor the population health of this iconic species to ensure its long-term survival.

"Humpback whales do not only play an essential role in their marine ecosystem but also represent an important economic resource, because whale watching is a booming industry in many Australian cities and around the world."

The collection of the whale blow was a non-invasive way for researchers to study whales, Dr Vendl said, and studying them also revealed the health of the marine ecosystem around the whales.

Whales usually fast during their migration north to warmer waters for breeding due to the absence of krill in large quantities along the Australian coast.

The migration, between May and September, is the best opportunity to spot whales off Newcastle and Port Stephens. It draws thousands to the region to see the aquatic giants in the flesh.

Fasting is therefore a major physiological strain during the whales migration," Dr Vendl said.

The study examined 20 whales in Hervey Bay during their journey south in August 2017.

The findings were compared to Macquarie University samples taken in May and June the same year for a separate study.

We concluded the physical strains of the migration, likely in addition to the exposure to marine pollutants, compromise the whales immune systems and consequently cause a shift in the whales airway microbiota," Dr Vendl said.

Our findings are the first to provide good evidence of a connection between the whales airway bacterial communities, their physiology and immune function something that has been established in humans.

Blow was collected using a waterproof drone carrying a petri dish over whales and "pure luck" in waiting for them to exhale while it was in range, and also with a telescopic pole.

"In Hervey Bay, the whales are curious and approach boats," Dr Vendl said.

"So, I held the pole out and waited until the whales exhaled and then collected their samples that way."

ACM has reported that the whale watching season along the region's coast has been a bumper one for enthusiasts.

The research comes days after a beaked whale fatally stranded at Magenta beach, south of The Entrance, earlier this week. National Parks and Wildlife confirmed it was only the seventh time that species had been beached on the Australian mainland.