Researchers at the University of St Andrews have sequenced whole genomes from humpback whales using DNA collected from their exhaled breath, in a development that could offer a less invasive approach to monitoring whale populations.

The technique uses small drones fitted with sterile Petri dishes, flown through the spray released when whales surface to breathe. The droplets, informally known as ‘whale snot’, contain genetic material that can be collected without darts, biopsies or close approaches by boats.

In research published in Molecular Ecology Resources, the team collected 58 samples from 26 individual humpback whales off the coast of British Columbia, Canada. Around 84% of the DNA in the samples came from the whales themselves.

Repeated samples from the same animals, collected during different encounters over two years, produced matching genomes. The results also matched biopsy-derived genomes from the same whales, while estimates of genetic diversity were similar between the two sampling methods.

The researchers used the data to determine the sex of every sampled whale, identify mitochondrial DNA variants and assess population genetics. The findings provide a population-level whole-genome dataset for North Pacific humpback whales, for which only one such genome had previously been publicly available.

Genomic information can help conservation researchers assess genetic diversity, inbreeding and population structure, as well as identify individual animals and investigate relationships between them.

Lead researcher Dr Éadin O’Mahony, formerly of the university's Scottish Oceans Institute, said the team hoped to use the data to investigate family relationships among whales foraging in northern British Columbia, including whether animals that feed together are related or form longer-term social bonds.

The samples also contained around 16% microbial DNA, largely from organisms living in the whales' airways. This could provide an additional source of information about respiratory health.

The work was conducted in Gitga’ at First Nation territory under research agreements with the community and the North Coast Cetacean Society. Drone flights were carried out under a Canadian fisheries research permit, with ethical approval from the University of St Andrews.

Pic: Operation Cetaces/ Claire Garrigue