Whale 'snot' reveals likely poor health during migration

July 29, 2020

Whale-watching season is delighting the viewing public along the east Australian coast but while it's a boon for the tourism industry, for the majestic humpback whale it's potentially a time of less optimal health.

UNSW Sydney researchers collected and analysed samples of whale blow - similar to mucus from a human nose - and found "significantly less" microbial diversity and richness on the return leg of the whales' migration, indicating the whales were likely in poorer health than when their journey began.

Microbial diversity accounts for the wide array of microorganisms - the smallest forms of life.

Lead author Dr Catharina Vendl, UNSW Science researcher, said the study, published in Scientific Reports this week, provided the first evidence whales' airway microbiota was a potential indicator of a whale's overall health.

East Australian humpback whales complete, on average, an arduous 8000-kilometre round trip between Antarctica and Queensland from May to November each year, fasting for most of their journey.

"The physical strains of the humpback's 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."

Humpback whales were almost hunted to extinction. The last whaling station in NSW, at Byron Bay, closed in 1962 because so few whales could be found.

Humpback whales are now protected throughout Australia, and in NSW are listed as a vulnerable species under the Biodiversity Conservation Act 2016.

Dr Vendl, who has a background in veterinary science, said it was amazing the east and west Australian humpback whale populations had recovered well in the years since whaling stopped.

"So, these whale populations are not endangered, but that doesn't necessarily mean things will stay that way," she said.

Collecting whale 'snot'

Dr Vendl said it was important to find a non-invasive method to study whale health, because many whale populations around the world were endangered - yet scientists still knew fairly little about whales' physiology.

"Many whale species are at or near the top of their food chain - so, a whale's general health can be a good indicator of the health of their marine ecosystem," she said.

"Humpback whales mostly live on tiny creatures called krill, but because there is less of this preferred food along the east Australian coast and it's such a huge effort for them to open their mouths to feed, they rely on energy stored in their blubber.

"Fasting is therefore a major physiological strain during the whales' migration."

Dr Vendl collected airway mucus from 20 whales in Hervey Bay, Queensland, during the humpback's return leg to Antarctica when the whales were several months into their migration in August 2017.

The researchers then analysed and compared the whales' blow microbiota to samples Macquarie University scientists collected near Sydney in May and June 2017, for a separate study, when the whales were at the start of their migration.

UNSW Science Professor Tracey Rogers pioneered the technique the UNSW researchers used to examine the whales' airway microbial communities, more than a decade ago.

Dr Vendl said researchers wanted to determine if there was a significant difference between the microbial communities of the whales at the start of and later on in their migration.

"I used two methods to collect the whales' blow while working from a boat. For one method, I flew a waterproof drone over the whales which carried a petri dish," she said.

"It was pure luck waiting for the whales to exhale at the same time the drone was within range for droplets from their blow to settle on the petri dish.

"My second technique was a 4.6-metre long telescopic pole with petri dishes attached to the end. In Hervey Bay, the whales are curious and approach boats.

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

Migration pressure link to potential poor health

The study found the whales' respiratory microbiota was severely depleted in diversity and richness the longer they fasted during their migration.

Dr Vendl said such changes often reflected a compromised state of health in the airways of humans.

"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.

"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."

Dr Vendl said a high level of bacterial variety and richness in respiratory microbiota was a sign of healthy airways in humans.

"I researched literature in human medicine: when you have a respiratory disease in a person, it also means the bacterial communities in their airways have changed and are usually depleted," she said.

"We had no idea if we would find a similar pattern in whales, but we at least showed the initial evidence for that occurring."

New potential for non-invasive methods

Dr Vendl said she hoped her research would lead to further study in non-invasive techniques to monitor whale health in populations around the world.

"Our findings showed the first evidence of a link between whales' respiratory microbiota and their overall health, but more research needs to be done," she said.

"Analysing whale blow to assess and monitor whale health opens up more possibilities for the use of non-invasive techniques, such as photogrammetry - where you fly a drone to film and measure whales to determine how much blubber they have and things like that.

"Other methods were outside the scope of my PhD, but it's important for researchers to experiment with and refine new techniques to assess their effectiveness in helping whale conservation."

Find the study in Scientific Reports: https://doi.org/10.1038/s41598-020-69602-x

University of New South Wales

Related Whales Articles from Brightsurf:

Blue whales change their tune before migrating
While parsing through years of recorded blue whale songs looking for seasonal patterns, researchers were surprised to observe that during feeding season in the summer, whales sing mainly at night, but as they prepare to migrate to their breeding grounds for the winter, this pattern reverses and the whales sing during the day.

Shhhh, the whales are resting
A Danish-Australian team of researchers recommend new guidelines for noise levels from whale-watching boats after having carried out experiments with humpback whales.

Fishing less could be a win for both lobstermen and endangered whales
A new study by researchers at Woods Hole Oceanographic Institution (WHOI) found that New England's historic lobster fishery may turn a higher profit by operating with less gear in the water and a shorter season.

North Atlantic right whales are in much poorer condition than Southern right whales
New research by an international team of scientists reveals that endangered North Atlantic right whales are in much poorer body condition than their counterparts in the southern hemisphere.

Solar storms could scramble whales' navigational sense
When our sun belches out a hot stream of charged particles in Earth's general direction, it doesn't just mess up communications satellites.

A better pregnancy test for whales
To determine whale pregnancy, researchers have relied on visual cues or hormone tests of blubber collected via darts, but the results were often inconclusive.

Why whales are so big, but not bigger
Whales' large bodies help them consume their prey at high efficiencies, a more than decade-long study of around 300 tagged whales now shows, but their gigantism is limited by prey availability and foraging efficiency.

Whales stop being socialites when boats are about
The noise and presence of boats can harm humpback whales' ability to communicate and socialise, in some cases reducing their communication range by a factor of four.

Endangered whales react to environmental changes
Some 'canaries' are 50 feet long, weigh 70 tons, and are nowhere near a coal mine.

Stranded whales detected from space
A new technique for analysing satellite images may help scientists detect and count stranded whales from space.

Read More: Whales News and Whales Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.