Scientists study Shark Bay dolphins to find out how their DNA can be used to find their age

Shark Bay dolphins have been at the centre of important work finding new ways to determine a dolphin’s age.

In total, 165 Indo-Pacific bottlenose dolphins, aged between 0 and 37 years old, were part of a joint study by researchers from University of Zurich, University of Canterbury, and University of New South Wales into how DNA function changes with age, meaning scientists may be able to use a sample of DNA to figure out how old a dolphin is.

Currently, a dolphin’s age can be found by extracting a tooth and analysing the growth layers of Dentine, which is difficult with a live dolphin, or it can be estimated by judging how many speckles are on their scale, which is not entirely precise.

Because of these challenges, many studies rely on dolphins that have been observed from birth, meaning their age is known.

Given how long the dolphins at Shark Bay have been studied, they made an ideal group for studying anything related to age, according to researcher Dr Katharina Peters of the University of Zurich and University of Canterbury.

“They have been subject of a long-term monitoring program for more than 30 years, so we know the age of many individuals,” she said.

The dolphins have also had many samples taken of them over the years, meaning their DNA can be easily studied, and meaning they were perfect for a study to measure the relationship between DNA and age in dolphins.

The study measured a process called DNA methylation, in which a DNA base is chemically altered, and tracked how methylation decreases during a dolphins lifespan.

The study of how the dolphins’ epigenetics (the impact of the environment and behaviour on how genes work) changes was used to build a “epigenetic clock”, a guide to identifying a Indo-Pacific bottlenose dolphin’s age through a DNA sample.

Being able to tell a dolphin’s age through a small piece of DNA in its skin will make it much easier to study dolphins,” Dr Peters said.

“The epigenetic clock we build can now be used by other groups that study the same species in other locations, where no long-term data on individuals’ ages are available.”

With knowledge of the ages of the Shark Bay population, the scientists hope to investigate areas such as differences in aging patterns in males and females, and the time in their lives where they have the most reproductive success.