Stock identification of Mediterranean horse mackerel (Trachurus mediterraneus) using morphometric and meristic characters

Morphologic differentiation among stocks of Mediterranean horse mackerel, Trachurus mediterraneus, throughout the Black, Marmara, Aegean and Eastern Mediterranean Seas, was investigated using morphometric and meristic characters. Discriminant function analysis of both morphometric and meristic characters suggested that there is restricted migration of mackerel among the adjacent seas. Overlapping of four Black sea samples on the discriminant space in morphometric and meristic characters suggested that there is one self-recruiting population in the area. The Marmara sea samples were the most isolated samples from all others for both morphometric and meristic characters, which may indicate existence of a distinguishable mackerel stock in the area. The sample from the Aegean Sea was grouped with one geographically close Mediterranean sample based on morphometrics, and separated from all other Mediterranean samples based on meristic characters, suggesting some degree of intermingling between these areas. Examination of the contribution of each morphometric variable to canonical functions indicated that differences among samples seemed to be associated with the anterior part of the body. In meristic analyses, highest contributions to canonical functions were associated with the number of gill rakers and pectoral fin rays.