Tuna Farming in Japan and Mexico

Abstract

Presently there are 23 identified tuna stocks in the world: 14 fully exploited, 8 overexploited or depleted, and only a single skipjack stock deemed to be under exploited. Wild juveniles of ABFT (. Thunnus thynnus), PBFT (. Thunnus orientalis), SBFT (. Thunnus maccoyii), and YFT (. Thunnus albacares) are used to stock tuna ranches for "fattening" (grow-out, from advanced juvenile to slaughter size). Ranched tunas are taken from diverse stocks managed under various legal regimes and monitoring agencies, but all serve the fresh and frozen sushi/sashimi-grade tuna market. Because Japan commands the largest part of this market, it sets fishing and ranching trends throughout the world. In any country, as the level of affluence rises, food preferences tend to shift from those centered on starches to ones centered on protein, and Asian countries have a strong predilection for this protein to be provided by seafood products. The rise of China as an economic power already has shifted its status from being a net exporter to that of net importer of seafood products, and this change is becoming evident in global tuna markets. Consequently, all available information points to a significant and growing impact of human consumption, especially in Asia, on global tuna resources. Catch restrictions and the banning of international tuna trade clearly have failed to achieve management of tuna stocks for sustainability; so, it is now incumbent to offer proactive strategies rather than reactive approaches. Such strategies need to be ones that academic institutions, international tuna markets, fishing fleets, and tuna farmers as well as regulatory agencies and environmentalists can endorse. Such is the justification for this chapter, which offers content relevant to both ecological and economic perspectives of tuna aquaculture. The solutions presented are straightforward and the science we now have in hand is strong enough to pursue them. As Roger Payne put it: "Act - that's what's so important."