Being able to determine the age of Octopus vulgaris should lead to better management of the resource. (Photo: Stock File)

Octopus’ age no longer a mystery

SPAIN
Friday, September 04, 2009, 16:00 (GMT + 9)

Researchers from Spain and Chile have succeeded in determining the age of common octopus (Octopus vulgaris) specimens captured off the coasts of Galicia and the Mediterranean Sea for the first time ever.

In the experiment, which was carried out in Toralla Marine Sciences Station, in Spain, participating biologists included a team from the University of Vigo; the Chilean scientist Consuelo Hermosilla; Angel Guerra, of the Vigo Marine Research Institute (IIM); and Italian professor Graciano Fiorito.

During the research project, scientists discovered that the octopus hides the secret of its age in a small cartilaginous structure of about five centimetres located in the species’ head.

Biologists verified that this sting (the vestige of a primitive shell) accumulates a layer of tissue every day of its life, similar to the rings that form in the trunks of trees.

“A pair of experiments have been conducted with the stings of other species in countries like Australia, but until now no structure had been found that determined the age of the Octopus vulgaris or common octopus, the most important from the fishing point of view,” explained Francisco Rocha, IIM researcher.

It is hoped the study will contribute to managing the capture of the cephalopod and bring it a step closer to being bred in marine centres.

The experiment consisted of capturing specimens in Galician and Mediterranean waters and injecting them with oxytetracycline, a substance that adheres to the area of growth, leaving a fluorescent mark, La Opinion de La Corunna reports.

The octopus were sacrificed after some weeks, to analyse the tissue microscopically and determine how many layers had formed in that period.

“First we looked for the oxytetracycline mark in the dark and, once located, we counted the layers. It must be known at what age they mature and at what age they are being harvested to ensure that the next generation is guaranteed,” Rocha explained.

In addition, this technique will contribute to clarifying the longevity of octopuses.

“Traditionally, it was said that they died after reproducing, but the females survive for a time to take care of their eggs until the larvae are born. And it is believed that a specimen could remain alive and coexist with the next generation. One of the ways to prove this is to determine its age,” he indicated.

Meanwhile, the Russian expert Chingis Nigmatullin, one of the world’s leading authorities on cephalopods, confirmed he would collaborate in the research and work at the Toralla Marine Sciences Station for a number of days.

Rocha pointed out that no technique has yet been developed that guarantees a larvae positing rate and profitable harvest.

For now, “the index is so low that the price of the octopus would be prohibitive,” he said. However, he believes that current obstacles can be resolved “in a few years."

By Analia Murias
editorial@fis.com
www.fis.com