Mar. Mamm. Sci. doi:10.1111/j.1748-7692.2008.00277.x (2009)

Water ejected from whale blow holes can be used for research into the animals' hormonal state, and possibly gender.

Researchers studying terrestrial mammals can measure hormone levels in faeces and urine; with aquatic mammals, such non-invasive monitoring is difficult. Using nylon stockings mounted on 13-metre carbon-fibre poles, Carolyn Hogg of the University of New South Wales in Sydney, Australia, and her colleagues sampled the exhalations of humpback and northern right whales they were following to see whether these might provide a source of hormonal data.

The team discovered progesterone and testosterone in some of the blows. Testosterone collected from single whales escorting female–calf pods supports theories that escorts are males waiting to breed. However, further testosterone/oestradiol tests are needed to definitively determine the whales' sex.