(CP / 08-09-09) Experts from the University of Vigo and the National Research Council (CSIC) have managed to calculate the age of common octopus (Octopus vulgaris). It is a finding that will improve fisheries management for this species, the most important commercially

The discovery was presented in the context of CIAC'09, the Cephalopod International Advisory Council, held from yesterday to Friday, September 11th, in the city of Vigo (Pontevedra, Spain). The event, organized by CSIC and held for the first time in Spain, brings together over 200 international scientists to share the latest findings on cephalopods, a category that includes more than 700 species, including octopus, squid and cuttlefish.

CSIC researchers Ángel Guerra and Ángel González, organizers of the meeting, say that “the aim of the congress is to update knowledge about the biology, ecology and culture of cephalopods. It is expected that the results of what is debated at the symposium have an impact in the areas of production and management of these resources.”

Many researchers are going to present their latest results here. This is for example the case of the study carried out by researchers from the University of Vigo and the CSIC, who have been able to calculate the age of Octupus vulgaris or common octopus. “In collaboration with Francisco Rocha and Consuelo Hermosilla we have found that in the stylets of these animals [residual internal shell] it appears a ring of organic matter per day, which can calculate the animal's age,” says Ángel Guerra.

This is somewhat similar to the otoliths of fish or, out of the marine environment, the rings that calculate the age of trees, although in this case the periodicity is annual. “Although something similar had been done with Octupus palidus, an Australian species, this is the first time this has been done with Octopus vulgaris, the most common species and the most important from the commercial standpoint,” says the researcher from the CSIC.

The finding is important because it can determine the age of each individual and know the period of growth and reproduction, which will improve the fisheries management of the species.

Another aim of the meeting is to make a list of cephalopods that are endangered or threatened by overfishing or destruction of natural habitats, since there is no official count for the moment.

“We think it could be a dozen threatened species of cephalopods worldwide. From here we will propose the Octopus macropus to be included. It is a species that used to be common in the Spanish coast and that the sailors thought that attracted the bad weather” says Guerra.

CLIMATE CHANGE AND FISHERIES MANAGEMENT

In the same vein, another issue to talk about is the influence of climate change on populations of cephalopods, a topic that has also been chosen for the closing conference.

According to Guerra, “In recent years we have been studying which environmental parameters affect the survival of these species and how they condition the survival of the larvae and, therefore, the abundance of a species for future fishing seasons, since adult cephalopods die after reproduction.”

These parameters, which depend on climate and oceanography, are the force of wind and sea currents (related to the outcrops and, therefore, to the presence of nutrients or mineral salts dissolved in water), and the amount of phytoplankton and zooplankton, which determine the survival of the larvae of the cephalopods and many other marine organisms.

The researcher illustrates it with the change in recent years in areas of Galicia and Portugal, where the average water temperature has risen one degree, affecting environmental conditions: “This has caused the arrival of species that used to live farther south, while some of ours move further north. What we want is to pool together all these changes in environmental conditions to watch how they affect each of the species,” summarizes the scientific from the CSIC.

The researchers will also study the effect of pollution on mortality in early stages. In this sense, they will talk about the effect of heavy metals, toxic components of the paintings of ships, organochlorines or organic matter that comes from urban pollution.

Apart from the CSIC, the event is sponsored by the “Xunta de Galicia”, the Ministry of Science and Innovation, the International Council for the Exploration of the Sea, the Zoological Society of London, the University of Vigo and the Mayor of this city.