First global approach: morphological and biological variability in a genetically homogeneous population of the European pilchard, Sardina pilchardus (Walbaum, 1792) in the North Atlantic coast

The European pilchard Sardina pilchardus represents the most commercially relevant fisheries resource in many countries bordering north Atlantic coasts and the Mediterranean Sea, being especially significant along the coast of Morocco. The continuous exploitation of this pelagic species for several decades places Morocco as the leader in sardine production. However, the conditions of exploitation of this resource underwent a great change during the last recent years. In order to identify the populations of the European pilchard sardine (Sardina pilchardus, Walbaum, 1792) in the Atlantic coast of Morocco and Spain, we have combined the truss network data to conduct multivariate analysis with biologic parameters and genetic analysis based on Microsatellite and mitochondrial control region data. Sardine morphometrics data truss variables from 10 samples spanning the Atlantic coast of Morocco were analysed by multivariate analysis. Thirteen morphometric measurements and some biological parameters such as the sex and the age of fishes were made for each individual. Discriminant analysis on size-corrected truss variables and cluster analysis of mean fishes shape using landmark data indicate, that the shape of north Moroccan sardines is distinct from the shape of sardines from south Morocco. However the analysis of the mitochondrial region and four microsatellites loci (Sp2, Sp7, Sp8 and SpI5) demonstrated an homogeneity population in the Moroccan Atlantic coast, with a low but significant genetic differentiation, which followed an isolation-by-distance pattern according to Mantel test.