Embryonated eggs of bluefin tuna. (Photo: IEO)

Bluefin tuna breeding breakthrough may spur sustainability

SPAIN
Thursday, July 02, 2009, 22:40 (GMT + 9)

A team of researchers of the Murcia Oceanographic Centre, a branch of the Spanish Oceanography Institute (IEO), was able to breed bluefin tuna (Thunnus thynnus) in captivity, a feat that opens up the possibility of raising this species sustainably.

Scientists secured several placements of more than five million viable bluefin tuna eggs by means of hormonal induction between 29 June and 1 July, in the facilities located in El Gorguel, Cartagena, Murcia.

Spanish researchers stressed that this is the first time such large quantities of fertilised eggs from Atlantic bluefin tuna females have ever been obtained in captivity.

According to IEO sources, this research project is “the fundamental and essential step to close the biological cycle of bluefin tuna in captivity and to be able to produce it by means of aquaculture, and thus diminish pressure on the wild stock, presently seriously threatened by over-exploitation.”

Researchers explained that this same experiment “had been attempted without success in many countries, but it was not possible to get Atlantic-sourced bluefin tuna females in captivity to lay eggs that were then fertilised by males. At most, a scarce number of viable eggs had been obtained, able to become bluefin tuna larvae and be developed.”

For the IEO, the event is a landmark for Spanish science and “changes the situation and opens the doors to bluefin tuna breeding and its production by means of aquaculture, although the problems that will occur in the growth process of tuna born in captivity, certainly, must still be resolved.”

The first egg placements were managed by the company Tuna Graso, which is owned by the firm Grupo Ricardo Fuentes and partner of the European research project SELFDOTT (Self Sustained Aquaculture and Domestication of Bluefin Tuna).

As part of this project, co-funded by the European Union (EU) Framework Programme and coordinated by IEO researcher Fernando de la Gandara, institute experts hormonally induced tunas by means of implants applied underwater, and secured a placement of more than two million viable eggs 72 hours later.

Similarly, they continue producing eggs daily, which are gathered by researchers to initiate experiments on larval culture under the SELFDOTT project in the Oceanographic centre of Murcia, under the supervision of expert Aurelio Ortega.

The SELFDOTT project aims to use the knowledge obtained in artificial bluefin tuna breeding to both obtain viable eggs and study the embryonic and larval development of the fish for juvenile production, Europa Press reports.

The juveniles and mature tuna specimens are set to remain in captivity in two locations in the Mediterranean, for use in studying puberty, gamete production and the influence of diet on the maturation and quality of the same.

By the project’s end, researchers expect to have drafted a protocol of recommendations for the development of larval culture on an industrial scale, thus improving the competitiveness of the Spanish and European aquaculture industry.

Researchers are looking to use breeders located in floating cages in El Gorguel and the Bay of Marsaxlokk, Malta in their continued development of the SELFDOTT project.

By Analia Murias
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