ELLSWORTH – There’s a lot we don’t know about lobsters. The crustaceans are iconic here in Maine, but we have trouble pinning down something as elementary as their age.
But maybe not for much longer. English researchers say they may have found a way to accurately tell how old lobsters are with a new DNA-based technique developed at the University of East Anglia.
Until now, researchers arrived at a lobster age by using its size. It’s been guessed that they could live as long as 100 years but pegging the age could never be totally accurate because individual lobsters grow at different rates.
Lobsters grow hard, inelastic shells, so as they grow, they must shed their old ones and replace them with new ones. Factors such as food availability and water temperature can affect growth rates, meaning lobsters don’t all molt at the same time.
“For a long time, it appeared that there was no accurate way to quantify a lobster’s age,” said Martin Taylor, a scientist at the university’s school of biological sciences, in a statement. “Some research suggested that you could tell a lobster’s age by counting the rings in parts of their eyestalks and stomach — a little like counting tree rings. But you can’t do that for a living lobster.”
So, Taylor and his team set out to develop a new non-lethal way to age European lobster with the hope that it could help give more accurate population assessments and in turn allow for more sustainable fisheries management.
In a study published last month in Evolutionary Applications, the scientists used a method that relied on quantifying DNA changes that accumulate over time. The amount that methyl groups changed in the DNA correlated with lobster’s age.
The researchers used hatchery raised lobsters, allowing them to know the exact age, as well as wild-caught European lobsters in the experiment.
“We identified a very strong relationship between age and DNA modifications, which allowed us to accurately estimate the ages of individual lobsters,” Taylor said. “Applying this method to wild lobsters predicted ages that generally aligned with minimum estimates of age based on size.”
The method does seem more precise for younger lobsters. The researchers were able to pinpoint the age within a month or so for lobsters 51 months and younger, but further work is needed for older known-age lobsters.
This is the first study to investigate what is known as the rDNA epigenetic clock of ageing in wild animals and it concluded that the method holds considerable promise.
“Having an accurate indication of lobster age will help fisheries, scientists and conservationists alike to understand, manage and conserve our vulnerable lobster stocks, working hand-in-hand with proactive fisheries management strategies, such as stock enhancement,” said Carly Daniels, the head of production science and development at the National Lobster Hatchery, in a statement.
In an email, Taylor said he believed that the method could also work for Maine’s American lobsters.
“The ribosomal DNA clock should in theory be applicable to American lobsters, but it would need to be calibrated on known age American lobsters in much the same way as we did in our study,” he wrote. “There may also need to be some modifications made to some of the methodology as a result of differences in the DNA sequences between the two species.”