Morphologic structuring between populations of chub mackerel Scomber japonicus in the Black, Marmara, Aegean, and northeastern Mediterranean Seas

Abstract

Morphometric and meristic analyses of chub mackerel Scomber japonicus were used to discriminate stocks throughout the Black, Marmara, Aegean, and northeastern Mediterranean Seas. Morphometric and meristic analyses showed a similar pattern of differentiation between S. japonicus stocks and revealed a clear discreteness of two groups, northeastern Mediterranean (Antalya Bay–Iskenderun Bay) and the northern group, including the Aegean, Marmara, and Black Seas. Univariate analysis of variance showed significant differences between means of the samples for most morphometric and meristic descriptors. The contribution of each variable in distinguishing between the stocks for the first discriminant function revealed high contribution from head size measurements for morphometrics, and first and second dorsal fin rays for meristics. Plotting all specimens on the first two discriminant functions accounted for 76% of total variance for morphometric and 69% of total variance for meristic analyses, and both plots resulted in two main groupings. The overall random assignment of individuals to their original group was higher in morphometric than in meristic analysis.