This is why it is so difficult to know the age of a lobster


Studying their DNA can help humans maintain a natural balance between populations.

It’s a Inside science story.

Lobsters can live surprisingly long lives, but it’s actually pretty hard to tell how old they are at any given time. As they grow they molt and develop new hardened exoskeletons every few years. This means that the telltale physical signs of aging do not significantly accumulate. Size is most often used to approximate a lobster’s age, but this method is “particularly difficult because individuals have very different growth rates,” said Martin Taylor, a molecular ecologist at the University of East Anglia in the UK.

This has long posed a challenge for conservationists and fishermen, who must ensure that sufficient numbers of reproductive age members of a given lobster population remain protected (and off your plate) to keep their local species in. life (and on your plate in the future). But now, a new study from Taylor’s lab has demonstrated for the first time a method of aging a lobster that doesn’t rely on its physical characteristics. Instead, all it takes is a DNA sample.

The key lies in the build-up of molecules known as methyl groups, the paper explains, published online September 23 in the journal Evolutionary Applications. These molecules are attached to DNA strands one by one over time in a process called methylation and can alter gene expression. In humans, things like diet, smoking habits, environmental factors and aging can cause methylation (and demethylation). The causes are probably similar in lobsters, where the build-up of methyl groups on strands of DNA builds a so-called “epigenetic clock” – a record of their lifespan.

When the research team, led by postgraduate researcher Eleanor Fairfield, took DNA samples from the legs and antennae of 155 lobsters of known age between 0 and 51 months, they found that the older lobsters had more methyl groups attached to their DNA than the younger ones.

The technique could bring a new level of precision to a wildlife management concern that has never been a matter of expert guesswork. But the document is still primarily a proof of concept that won’t lead to a new tool being developed anytime soon, Taylor explained. DNA extraction and analysis is a laborious and time-consuming process, using expensive equipment that would be of no practical use aboard a fast-paced fishing boat. And even a magic pocket tool that could do all of this in an instant would still require data on the methylation patterns of lobsters in the region, as well as a better understanding of the rate of variation between local animals.

“It may be that in very cold regions, methylation builds up slower or faster,” Taylor said. His lab is now looking at how methylation varies in lobsters of the same age in different environments and is also studying lobsters up to six years old to see if the sliding methylation scale continues.

Ultimately, this discovery could help humans protect lobsters by keeping their populations as naturally balanced as possible.

“If you heavily exploit the population, you could wipe out all of the large individuals or all of the small individuals,” Taylor said, making it more difficult for that population to adapt to changes in the environment. “It has been shown that in general, a natural age structure in a population is much more resilient.”

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