Blows reveal sex drive in whales

Humpback whale exhaling 'blow'. (Image copyright C. Hogg)
Wednesday, 8 April, 2009
Dan Gaffney

Using a 13-metre long carbon fibre pole to place nylon stocking above whales' blowholes as they surfaced to breath, an international team of scientists has pioneered a harmless new way to monitor the reproductive health and status of the huge marine mammals.

Reporting in the latest issue of the journal Marine Mammal Science, the international team was able to detect sex hormones in the "blow" - or exhaled breath - of samples collected at sea from 35 North Atlantic northern right whales and from 18 humpback whales migrating along the Australian east coast.

It is the first time this non-invasive technique has been used to identify reproductive hormones among free-swimming cetaceans.

The nylon captured tiny traces of mucus and lung cells exhaled in the blow, which were analysed for the presence of male and female hormones and matched to the observed gender of the individual whales.

It is hoped that the experiments may help to shed light on why the North Atlantic right whale is breeding in such low numbers that there is concern among scientists for the species' recovery.

The new method is easier and more efficient than the current strategy of faecal sampling, which is difficult among free-swimming whales and only feasible when the creatures are feeding.

Scientists have speculated that the North Atlantic right whale's low breeding rate may be due to breeding dysfunction or hormonal abnormalities governed by the endocrine system, which is poorly understood in large whales.

The mammalian endocrine system releases hormones throughout the body that regulate metabolism, growth, development, puberty, the menstrual cycle, sexual arousal and reproduction.

The researchers detected testosterone and progesterone hormones in both whale species using liquid chromatography-mass spectrometry tests. This powerful analytic technique allows the detection and identification of individual chemicals, such as sex hormones within a complex mixture.

"The ability to detect measurable levels of testosterone and progesterone in the blow of large whales is probably due to their diving adaptations," says Dr Tracey Rogers, a UNSW biologist who co-authored the paper with Dr Carolyn Hogg (UNSW) and researchers from the US and Scotland.

"Whales breathe less frequently and tend to exchange a larger percentage of their total lung volume with each breath than land animals. The heavy vascularisation of the lungs probably allows different compounds to pass from their bloodstream into the lungs, which are coated in mucus. Due to the volume of air exhaled by the whales and the presence of mucosa in the blow, we can use blow sampling for hormonal analysis in large whales."

It's not yet known whether blow sampling among whales can be used to determine the hormonal condition or sex of an individual but the researchers plan to further studies using genetic sampling to determine the method's validity.

Media contacts:
Dr Carolyn Hogg - 0407 003 248
Dan Gaffney - UNSW science media - 0411 156 015