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Massive Bluefin Tuna Spawnings In Captivity

Breeding & genetics

Scientists from the Instituto Espaol de Oceanografa (IEO) have once again obtained viable bluefin tuna spawnings in their facilities in Murcia without the need for hormonal induction.

A new opportunity to study the way in which this endangered species reproduces in captivity. The researchers are confident that they will achieve far greater results than those obtained over the past two years wherein survival rates of between 73 and 110 days respectively, were obtained.

Since June 9th at the research plant belonging to the Murcian Oceanographic Centre, part of the Spanish Institute of Oceanography (IEO) they have been collecting spawnings of viable bluefin tuna eggs within the framework of the SELFDOTT project (From capture based to SELF-sustained aquaculture and Domestication Of bluefin tuna, Thunnus tynnus), coordinated by the researcher Fernando de la Gándara.

The tuna, a broodstock of around 60, are housed in two floating cages 25m wide x 20m deep in the bay of El Gorguel (Cartagena), managed by the company Caladeros del Mediterráneo S.A belonging to the Ricardo Fuentes Group, participant in the SELFDOTT project.

This company, via the biologist Antonio Belmonte, is responsible for the management and maintenance of the broodstock which has led to the obtaining of the massive spawnings that reached more than 10 million eggs in a single day.

In the year 2009 the first spawnings were obtained after hormonally inducing the broodstock with GnRH implants and in 2010 and also this year the spawning were obtained spontaneously without the need for hormonal induction.

This is the third consecutive year that the IEO has obtained viable spawning from bluefin tuna which indicates that the broodstock has reached a very important degree of domestication as a consequence of their stay in the aforementioned experimental cages for more than four years.

The objective now is to lay out the basis for the development of techniques that allow the closing of the biological cycle of this species and the production of juveniles through aquaculture techniques independently from natural populations. Aurelio Ortega, a researcher at the Marine Culture facilities in Mazarrón belonging to the IEO, will head up this part of the project. Furthermore, part of the spawning will be sent to the hatcheries belonging to the rest of the project associates, located in France, Greece, Malta and Israel.

The researchers from the Tunids Culture Team at the IEO are confident in gaining far superior results than those obtained over the past two years where survival rates of between 73 and 110 days respectively, were achieved. In order to achieve this they have been able to rely on the collaboration of a Japanese expert in Pacific bluefin tuna culture, Manabu Seoka who is currently acting as an external chair at the Polytechnic University of Cartagena.

The bluefin tuna is an emblematic species that has been feeding Mediterranean populations for thousands of years. Over fishing that it has been subjected to has led to its fishing being currently regulated by the setting up of quotas to limit its capture. However, only its integral production via aquaculture techniques, such as is the case nowadays with species such as sea bream, sea bass, turbot or salmon, can guarantee its consumption in quality and quantity as required by and ever more important and selective market, reducing the pressure on natural populations and contributing to its overall recuperation.

July 2011