Fishery genetics of Mediterranean bluefin tuna: Review of existing data, on-going studies and perspectives

We critically reviewed the contributions of fishery genetics to the understanding of spatial population structure and dynamics in Mediterranean bluefin tuna by comparatively integrating existing data with those recently obtained from on-going surveys. Microsatellite-based population genetic studies provided coherent and informative evidences which consistently indicate a spatial genetic structure of Mediterranean bluefin tuna. By integrating the existing genetic data with those obtained from other approaches, it is likely that the Mediterranean is inhabited by reproductively isolated subpopulations, displaying different spatio-temporal population dynamics. On-going bluefin tuna genetic surveys addressed the identification of such subpopulations in the bluefin tuna catches from a Sardinian trap. However, the genotyping of 275 bluefin tuna individuals collected over five years performed on six neutral and 10 underselection microsatellite loci did not provide evidence of genetic heterogeneity within catches. The lack of genetic heterogeneity signals within tuna trap catches might be related to the inadequateness of these marker loci. A new genomic approach using a huge number of underselection SNPs (Single Nucleotide Polymorphisms) might represent a promising tool to resolve the complex bluefin tuna population structure and traceability.