Mitochondrial DNA sequence variations in populations of Sardina pilchardus (Walbaum 1792) along the Tunisian coasts

Sardine is a fish species of great economic importance to Tunisia. Knowledge of genetic diversity and population distribution is essential for efficient management and sustainability of any regional fisheries. This study is aimed to assess the genetic structure of the sardine and to specify the stocks of the European sardine (Sardina pilchardus). In all, 83 specimens were collected from three locations along the Tunisian coast and analyzed using mitochondrial DNA sequences. The results of sequence analysis determined the existence of variations in 40 single nucleotide sites within the 307 bp fragment of the cytb gene examined and defined twenty different haplotypes. Genetic diversity, estimated by haplotypic diversity, was high in all samples. Tunisian S. pilchardus samples show some level of genetic structuring. First, genetic differentiation between localities (Phi(ST) estimates) was significant for all comparisons. Second, the analysis of molecular variance AMOVA indicates a high level of genetic variation (Phi(ST) = 0.093; P<0.001). The structural patterns identified can be explained largely in relation to the regional oceanographic features. In conclusion, this study provided initial genetic data in making inferences of the genetic structure of S. pilchardus along the Tunisian coasts.