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New method helping scientists gauge age of B.C.’s Southern Resident killer whales

Exploring their ‘epigenetic clock’ could identify trends and stressors within whale populations
Researchers from NOAA’s Fisheries Northwest Fisheries Science Center and other scientists have used a new technique to determine the age of southern resident killer whales and other whales. Pictured is a new baby orca in the J-Pod of the Southern Resident Killer Whales, spotted off of the shores of Tofino. (Photo credit: John Forde and Jennifer Steven)

Scientists are using skin samples of endangered southern residents and other whales in what’s being touted as a promising new way to estimate the ages of the mammals.

It’s important to understand the life history of individual animals and how their population changes over time, but it can be difficult to accurately estimate the ages of wild beings – especially ones that live a long time as whales do – according to the National Oceanic and Atmospheric Administration (NOAA).

Researchers from NOAA’s Northwest Fisheries Science Center and other scientists used a new technique to determine whale ages before their findings were published in the scientific journal Molecular Ecology Resources in late March.

The whale age study relied on epigenetics, which explores how DNA gets modified or packaged within a cell. The researchers looked at one modification called methylation, which can switch genes on and off, and were able to assign an “epigenetic clock” to individual whales. Those estimates are expected to be within three years of a whale’s actual age.

“Accurately estimating the age of individual whales is important for understanding the health of individuals and trends in killer whale populations,” the U.S. environmental agency said.

The researchers examined skin cell samples from southern and Alaska resident orcas, plus Bigg’s killer whales. It also included Fisheries and Oceans Canada allowing Indigenous hunters in Canada to collect samples from bowhead whales – one of the planet’s longest-living mammals.

Through the epigenetic approach, scientists only need small skin biopsies that can be collected using minimally invasive techniques from the living animals. Assigning the epigenetic clock is then possible thanks to the strong correlation between methylation patterns and age that’s been documented in humans and nonhuman vertebrates, according to the study.

The study also used samples of whales that have died in the past and drew from data already collected on southern residents over previous decades as there’s a detailed record of many individuals belonging to the closely watched species.

“While we know a lot about the age structure of the southern residents, we don’t know every whale’s age,” NOAA said. “Most killer whale populations are not nearly as well-studied as killer whales in the Pacific. Epigenetic clocks can help fill in those gaps.”

The epigenetics aging methodology isn’t perfect though as NOAA notes that, just like humans, the cells of other mammals can age faster or slower depending on variables in their environment, such as diet, lifestyle and stress.

Still, NOAA said the strategy is expected to help scientists monitor patterns in age-related diseases and detect changes in survival and birth rates within whale populations. Examining the epigenetic data from killer whale populations around the world is also now underway, the agency said.

READ: Florida aquarium returning Lolita the orca to the Salish Sea after 53 years in tank

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Jake Romphf

About the Author: Jake Romphf

In early 2021, I made the move from the Great Lakes to Greater Victoria with the aim of experiencing more of the country I report on.
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