Octopuses are fairly short-lived animals, although their average lifespan depends on the species. Normally, the commonoctopus (Octopus vulgaris) lives between one and two years, while the giant Pacific octopus(Enteroctopus dofleini) can live between three and five.

As animals that die shortly after mating or laying eggs, and given that catches have doubled in recent decades to meet the nutritional needs of a growing global population, it is important to determine their age to ensure sustainable fishing while protecting the longevity of this animal.

Recently, a team of Australian scientists developed a practical guide to octopus ageing. According to IFL Science, it describes an accurate, reliable, economical and easy-to-use method for determining age and estimating how quickly these animals grow and reproduce.

How Do You Age An Octopus? Count Their “Rings” Like Trees
They always have kraken birthday parties.
IFLScienceEleanor Higgs

"Over the past 30 years, several studies have explored different methods for determining octopus age, but only a small number of researchers around the world have the practical knowledge to carry out these methods in the laboratory," says Zoe Doubleday, a marine ecologist at UniSA.

"It's crucial that we don't lose this practical scientific knowledge because, by determining their age, we can understand the impact of different fishing rates on the population," he added.

The paper, published in the Marine and Freshwater Research Journal, explains how to use the growth rings on octopuses' beaks and stylets - internal shells next to the gills - to validate their age (like tree rings).

A step-by-step guide to ageing octopus
Global octopus catch has doubled over the past four decades and is likely to grow in importance as many key fisheries continue to decline. Lack of age data is a critical limitation in assessing the resource status of octopus. Over the past ~30years, studies have investigated various methods to age octopus, with some methods better suited to certain species than others. However, only a small number of researchers have the hands-on knowledge to execute these methods in the laboratory. Here, we present the first step-by-step guide to ageing octopus, as well as a decision tool, which should enable readers to carry out the ageing process and make an informed decision on the most suitable method for their species. We provide guidance on age validation, increment analysis of both beaks and stylets, materials needed, as well as avenues for further research. We hope this guide will provide a starting point for researchers new to octopus ageing, and for those working with octopus species that have never been aged before. We also encourage researchers to use this guide as a forum for open discussion to support the ongoing development of effective octopus ageing methods.
CSIRO PUBLISHING

The stipes are formed in layers that are slowly deposited as the animal ages. Although they are a good way of measuring age, they vary between species in terms of shape and increment, so they may not be the best tool. Everything is complicated by the fact that octopus growth rings are measured in days, not years.

This guide therefore becomes an essential tool as "understanding the age of an octopus helps to maintain the sustainability of the fishery". "If we know the age of a species, we can estimate how fast they grow and reproduce and how much we can catch to maintain a sustainable fishery," said UniSA PhD student Erica Durante.


Scientists estimate that around 400,000 octopuses are caught every year in around 90 countries, a figure that is expected to rise.