Farmed Atlantic bluefin tuna in the Mediterranean are fed a mixed diet of frozen wild small pelagic fishes, mainly from the Mediterranean or outside the region. Most feed sources are not traceable. A traceability system would require aquaculture companies to prove the origin of the feed used. The fish-in-fish-out ratios are high, meaning that high volumes of fish inputs are needed to produce a kilogram of bluefin tuna.
Open net cage systems are likely to have high waste discharges and there is no evidence of mitigation. Open net cage systems will not cause serious habitat alteration. There are few reports of viral, bacterial and parasitic disease outbreaks.
The current management system for tuna farming in the Mediterranean Sea is marginally effective. The strategic environmental planning, environmental impact assessment, effluent discharge, water pollution and all of the management issues are marginally effective.