Soy products, Extrusion technology and nutrition: Towards the practical feeding of ranched tuna  

Tuna ranching in now recognized as a viable and very profitable enterprise worldwide.  Farming for several tuna species has been practiced commercially for over 24 years.  It began in Port Lincoln, Australia, in 1991 and it is now being globally introduced to tropical and subtropical regions.  In Mexico, the first operation was established in 1997, at Cedros Island.  Today, half a dozen Pacific bluefin tuna (PBFT, Thunnus orientalis) operations exist in Ensenada, just an hour south of the San Diego-Tijuana border.  

Among the main limitations that tuna ranching faces, current feeding practices are not only impractical and largely unsustainable but they pose ecological risks that require immediate attention.  The daily feeding of large quantities of untreated fresh or frozen fish/squid results in unreasonably high feed conversion rates (up to 23 to 1→ kg sardine fed to kg tuna produced).  The sardine's limited availability (the season only goes from April to September in northwest Mexico) also highlights the need for a balanced feed that would provide suitable nutrition for adult tuna, and would enable manipulation of key nutritional elements which, in turn, would allow management strategies to optimize performance of these fish.  

In this talk, a comprehensive and up-to-date overview of tuna nutrition will be presented together with preliminary results of an ongoing research project oriented a developing suitable formulations for some of the most commercially important tuna species being cultured today.  Building on previous successful efforts, the proposed biotechnology can support viable and responsible expansion of tuna farming, helping to circumvent the combined negative effects of pathogen introduction and less than optimal performance as it also develops a new industry.  In doing so, a sizeable and untapped market for quality raw materials including soy would be made ripe for American producers.