Abstract
The development of Atlantic bluefin tuna farm production in the Mediterranean, which relies on collecting tunas from the ocean, has created a number of recent challenges to managers of the wild stock. As a result, additional monitoring requirements have being imposed on fishing fleets and farming operations. Although the development of farming may have contributed to higher catches of tuna in the Mediterranean and may have shifted fishing toward more purse seine caught fish, such tendencies began before farming started in earnest. Since farming started, however, there has been a decline in the proportion of tuna harvested by longline fleets. Such changes in the mix of gears used to harvest tuna may have led to changes in the composition and amount of bycatch. The possible ecosystem effect of such changes in fishing practices are still to be evaluated and can only partially be associated with the development of farming. Other reported effects of farming include changes in ecosystem balance related to the shift in tuna diet of farmed fish from wild to human-provided, cages acting as fish aggregating devices and impacts of excess feed and tuna waste on benthos from cages set in relatively shallow areas. Ultimately, the major challenges remaining are to reduce the dependence which farming has on wild-caught tuna and seafood-based farm diets. Overcoming such challenges would benefit not only the farming industry but also the sustainability of the wild stock.