How human forcings affect ecological properties of large pelagic fish in the Mediterranean? Historical genetic changes in the overexploited bluefin tuna (Thunnus thynnus).

Based on a comparative analysis of genetic diversity at 7 microsatellite loci in ancient (archived skeletal specimens) and modern (freshly collected individuals) samples of Thunnus thynnus collected in the Mediterranean Sea, we assessed temporal changes and spatial variation of genetic and demographic (genetically-related) features in the overexploited Mediterranean stock of bluefin tuna. From the analysis of more than 300 individuals, a temporal stability of genetic diversity over about 90 years but significant changes in the genetic structure of the stock were achieved. Such results argue for an evidence that, in the Mediterranean, stock overexploitation has not yet corrupted the genetic potential of such living resource and that bluefin tunas are not fully panmictic.