Have you ever been whale watching, or seen a whale coming up to breathe? If so, you will have seen a spray rising from the surface as it takes a breath, before diving again. Did you know that spray is also known as whale snot?

Whale snot is made up of biological material such as DNA, hormones and bacteria from a whale’s lungs. A special team of drone experts, microbiologists, virologists and I have been working together to collect whale snot in a new and exciting way (read more about this in Frontiers in Marine Science). We are using custom-built drones to check whale health.

In the past, health assessments of whales were performed on those that had either been stranded - in which case their health was compromised - or deliberately killed, having been hunted. Today, collecting health information from whales without hurting them means collecting their skin (sometimes left floating in the ocean), their poo or their snot. Current methods to collect whale snot involve scientists using poles with petri dishes at the end. The scientists need to get very close to the whale in a boat, and hold the pole over the whale as it takes a breath. This can be dangerous, as it involves very close boat approaches.

My PhD research involves an industry collaboration with drone expert Alastair Smith from Heliguy Scientific. We are collecting whale snot using racing-style drones. They have a remotely operated flip-lid petri dish holder, which enables us to load a clean dish every time we collect whale snot.

We designed, built and tested our drone method off the coast of Sydney, Australia. Every year, humpback whales migrate north from their cool feeding waters in Antarctica, where they spend the summer feeding, to warm breeding grounds around Australia. We typically see humpback whales travelling close to the Sydney shore between May and November. This population is a conservation success story and has been recovering post-whaling at a rate of around 11% every year. There are now more than 30,000. This makes them the perfect study species for our method.

To collect whale snot, we headed offshore in a boat. Once a whale or pod (two or more whales) was spotted, the drone was launched into the air and flown over to the whale, 200 metres or more from the boat. Once in position, we used the drone’s camera to see when the whale was likely to surface. As it came up to breathe, the drone’s petri dish was opened and the drone was flown through the whale snot. Immediately afterwards, the petri dish was shut to minimize contamination of the sample, as the drone flew back to the research vessel.

In the lab, I used forensic techniques to identify the types of bacteria living in the whale's lungs. This was done using next generation sequencing, to provide a library of the types of bacteria found in our samples. We then compared our samples with samples of sea water and air collected off the coast of Sydney, to show that our drone was indeed collecting whale snot.

I was also able to compare our findings with similar studies conducted in the Northern Hemisphere, and found some overlap in the types of bacteria found in the snot of other whale populations. We can also use this information to help inform us about the health of stranded or sick whales.

Collecting samples over consecutive years - long-term sampling - may help us follow changes in the health of whale populations over time. The more samples we take, the better the picture we can build of their health. At the same time, we are also learning more about ocean health by sampling microbes living in our marine environment. For example, these whales could potentially be carrying microbes from Antarctica as they migrate to Australia. In the future, we could adapt this method to learn more about the health of threatened whale species, such as northern and southern right whales.

The collection of whale snot required university animal ethics, a scientific licence and a qualified Civil Aviation Safety Association drone pilot.