Commissioned by the Pew Environment Group, it finds that last year 140% more bluefin meat from the Med entered the market than was reported as caught.
The fishery's regulator, Iccat, put new measures in place two years ago aimed at stopping over-fishing, but Pew found there were still holes in the system.
The Atlantic bluefin is so depleted as to qualify as a threatened species.
In 2008, member governments of Iccat – the International Commission for the Conservation of Atlantic Tunas – agreed to implement a system of paper-based catch records, in principle allowing fish to be tracked from the sea to their final destination.
Read the complete article from BBC News