OVERVIEW AND RECENT PROGRESS ON TUNA AQUACULTURE  

The current status of tuna fisheries, fattening and farming practices, as well as advances in closed-cycle tuna aquaculture are summarized. The emergence and expansion of tuna fattening and farming activities during the last four decades has led to a shift from traditional fisheries towards aquaculture. This change is entirely reshaping the tuna fishery industry and the management of their stocks worldwide. Tuna fattening and farming operations still rely primarily on wild caught juveniles that are fattened using small pelagic fish, merging these activities and blurring the line between fisheries and aquaculture. Progress in fattening operations has been limited to improved management and decreased mortalities during the capture, towing, transferring, and feeding stages of the tuna in cages. However, tuna aquaculture is now rapidly changing due to remarkable progress in closed-cycle tuna aquaculture production through advancements in broodstock maturation, spawning, larval rearing, and juvenile production technologies. Indeed, following the pioneering achievement of closing the life cycle of the Pacific bluefin tuna (PBFT) in Japan, researchers the world over are now making significant progress in hatchery technology, including with yellowfin tuna at the IATTC-ARAP Achotines Laboratory n Panama. A number of other research and development projects have occurred in the past few decades examining the feasibility of closed-cycle production of other tuna and tuna-like species such as the bigeye tuna (Thunnus obesus), and blackfin tuna (Thunnus atlanticus). These species, while not as well known as bluefin and yellowfin tuna, are nonetheless valuable to the fishing industry. Given the smaller size of blackfin tuna and bonito, these species are easier to transport and maintain in smaller land-based facilities compared to the infrastructure involved in maintaining bluefin or yellowfin tuna broodstock in land-based tanks. We also present research data on blackfin tuna. This is the smallest of the true tuna species of the genus Thunnus, reaching 1 m and 20 kg within a relatively short life span of 5 years. While it is unlikely that blackfin tuna will ever compete in the same global marketplace of its larger counterparts, as a true Thunnus species it deserves attention for commercial aquaculture development, targeting another segment of the market - a smaller size, yet high-quality, sashimi-grade tuna.

Closing tunas life cycle and the development of ecologically and economically efficient feeds that meet their specific nutritional requirements are needed to ensure the future of tuna production and the conservation of tuna species. Efforts by researchers, academics and the global industry are making it possible to achieve these goals.