IIM-CSIC releases for the first time two octopuses, one raised in captivity, with transmitters to study their behaviour

Santiago de Compostela, February 14, 2022. The Higher Council for Scientific Research (CSIC), through the Marine Research Institute, will monitor the behavior and movements in the National Park of the Atlantic Islands of Galicia (PNIAG) of two specimens of octopuses released in the Cíes Islands archipelago -one hatched in captivity and the other wild-, both with acoustic emitters for locating them underwater.

The action is one of the tasks contemplated in the research project "Ecology of the common octopus in nature: solving its ecological unknowns to obtain sustainable fisheries management and aquaculture (ECOSUMA)", financed by the State Plan. It began in June 2020 and will end in 2023. It is led by the Ecology and Marine Resources group (Ecology and Marine Biodiversity working group) and has the participation in marking tasks of Ángel González, Santiago Pascual and Álex Alonso ( of the Fishing Ecology working group, within Ecology and Marine Resources), as well as other researchers from the working group such as Gonzalo Mucientes, from the Instituto Português do Mar e da Atmosfera (Ana Moreno), from the Profand Group (Álvaro Roura) and staff technician from the CSIC and collaborating companies.

“With this action we intend to study the spatial ecology of juvenile and adult octopuses in the scope of the PNIAG. For this, we transported two specimens that were released during sampling dives and under controlled conditions. Previously, they were marked by placing an acoustic emitter on a specific support located in the anterior area of ​​the mantle. It is the first time that this methodology has been applied to the common octopus, although there is evidence of previous attempts. To obtain movement data, we will use the set of acoustic receivers previously deployed in the study area within the framework of the TAC project of the Fisheries Ecology group, financed by the Biodiversity Foundation”, explain Ángel González and Santiago Pascual, principal investigators of the ECOSUMA project, who add that "around summer, "we hope to obtain the first data on the individual behavior, use of space and movement patterns of these two marked octopus specimens".

Once this acoustic marking system has been validated, the same methodology will be applied to other wild specimens during the summer. On the other hand, over the next few months, scientists will investigate the trophic relationships of the common octopus in the two critical phases that produce high mortality in captive conditions, the octopus specimens that live their last previous phase before settlement and those that have recently settled in the bottom. "These activities, together with the knowledge of the environmental conditions that govern its entire life cycle, will allow us to move towards an ecosystem approach for the management of this important resource," says Ángel González.

The ECOSUMA project

“On a global scale, we have been working since 1960 on the comprehensive breeding of cephalopod species, among which the octopus stands out, in a context marked by two major factors that affect the productivity of marine resources: climate change and overfishing. The main bottlenecks in the integral rearing of the octopus up to now go through the ecology of the larval phase and the settlement of the larvae on the seabed. For this reason, it is key to delve into the nature of the ecology of the larval stage, the pre- and post-settlement juveniles and the trophic relationships during these phases, linking these factors with the oceanographic ones that affect the life cycle of this cephalopod”, point out the researchers. scientists, who add that “the factors responsible for the success of recruitment in cephalopods depend largely on the interactions between the phases of egg mass, newborn and pre-recruited subadults and the physical and biological environment that prevails during each phase. ”, explain the scientists.

Over the last two decades, the Ecology and Marine Resources group has led several multidisciplinary projects that provided the importance of meteorological, physical and biogeochemical frameworks in the ecology of cephalopod paralarvae in an area of ​​fishing importance (Cíes Islands fishing ground, foreheadto the Vigo estuary). In addition, it is currently collaborating with the Profand Group to advance in the integral cultivation of octopus.

In this context, the group develops the ECOSUMA project with the task of investigating various aspects of the life cycle of wild cephalopod paralarvae that must be resolved in order to improve and increase the possibilities of reaching an integral culture of the species, specifically, in those related to the wild phases prior to settling on the seabed and juveniles, practically unknown until now.

"We intend to advance in the knowledge of two unexplored phases of the life cycle of the common octopus - the larval stage in the plankton and the beginning of the juvenile stage in the bottom - in the wild to transfer this knowledge to obtain a sustainable integral culture of the species at an industrial level, which until now is not possible in high survival rates”, says Ángel González.

Other objectives are to obtain more information about the elusive wild paralarvae that have between 4 to 22 suckers per arm and the oceanographic influence during this little-known planktonic phase. Furthermore, other objectives are to expand the historical series of recently hatched common octopus paralarvae with 3 suckers per arm or to create the first biobank of mesozooplankton samples and associated data under 9001 certification.