SELFDOTT

"From capture based to SELF-sustained aquaculture and Domestication Of bluefin tuna, Thunnus thynnus"

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 Obiettivo del progetto (Objective)

'SELFDOTT proposes to implement knowledge already obtained on the artificial control of reproduction of the Atlantic bluefin tuna (BFT), Thunnus thynnus, to obtain viable eggs, and study embryonic and larval development for the production of fry (juveniles). At the same time, suitable and environmentally performing feeds for the growout of BFT will be developed, thus reducing or eliminating the practice of raw fish importation and feeding by the fattening industry. Wild juvenile and mature BFT will be reared in captivity at two sites in the Mediterranean, and will be used to study puberty, gametogenesis, and the influence of diet on reproductive maturation and gamete quality. Mature fish will be induced to spawn using hormone implants and the eggs will be collected using devices designed specifically for cages. To establish the knowledge-base for controlled development of BFT larvae, the mesocosm and artificial larval rearing methods will be employed. The ontogenesis of essential biological functions will be studied, including environmental perception, digestion, immunity and behaviour. A protocol for the commercial-scale larval rearing of BFT will be recommended at the end of the project. Whole body and stomach composition of wild fish will be analyzed and serve as a guide to formulate nutritionally complete artificial feeds for BFT. Juveniles will be captured from the wild, adapted to captive conditions and used to carry out weaning and feeding experiments, using moist and dry pelleted diets. The environmental impact of the formulated feeds will be examined and compared to existing raw-fish practises. SELFDOTT will produce the basic knowledge necessary for the development of a self-sustained aquaculture industry for the BFT in the Mediterranean, thus enhancing the competitiveness of the EU aquaculture industry, while at the same time reducing the pressure on the wild BFT stocks and ensuring the conservation and recovery of this magnificent fish.'

Introduzione (Teaser)

Atlantic bluefin tuna (BFT) (Thunnus thynnus) is one of the most magnificent fish in the sea and has been highly prized since the time of the Ancient Greeks. Sadly, the numbers of bluefin tuna are rapidly decreasing due to overfishing fuelled in part by the demand for sushi and sashimi in Japan, Europe and North America.

Descrizione progetto (Article)

An industry based on the capture of tuna has developed in the Mediterranean Sea in recent years. The process involves taking wild fish during their migration and fattening them in cages for periods ranging between two months and two years. An alternative to the fishing and capture of BFT is to farm them in a sustainable way, which can help relieve the pressure on wild stocks, but cannot completely replace fishing altogether.

The EU-funded Selfdott project was established to help develop BFT aquaculture by obtaining fertilised eggs and studying the embryonic and larval development for the production of juvenile fish. A better understanding of the life cycle of the BFT will help improve management of wild stocks.

Wild juvenile and mature fish were reared at a site in southern Spain and a site in Malta. Adult fish were induced to spawn using an implant loaded with gonadotropin releasing hormone analogue (GnRHA). The Spanish fish spawned two days after treatment and the fertilised eggs were collected. The Maltese fish did not spawn, possibly as a result of lower water temperature at the site.

The next challenge was to ensure the survival of the larvae by investigating optimal light levels, hydrodynamics, surface cleaning, microalgae, feeding sequence and nutritional quality. Scientists applied techniques originally developed for bonito, a type of mackerel which belongs to the same family as BFT.

Juvenile tuna grow extremely rapidly; as a result they have very high nutritional demands. Researchers conducted feeding trials with young BFT. A diet of raw fish was compared to a diet of artificial food and the results showed that tuna require a diet that is high protein and low in fat. The project's findings will aid the development of pelleted feed for growing juvenile fish, thereby reducing the need to import raw fish for the fattening industry and the emerging tuna farming sector.

Sustainable farming of BFT will be able to help conserve wild stocks by meeting some of the global demand for the fish. Consumers will also benefit because farmed fish are of a standard quality and can be easily traced, thereby allowing people to know exactly what they are buying.