Spatial variability of helminth parasites to recognize the discrimination of juvenile and young adult areas of horse mackerel, Trachurus trachurus (Linnaeus, 1758) off the coast of Tunisia

•Ten parasites were used as biological tags to discriminate Trachurus trachurus from Tunisia coast in three different areas.•Fish from Bizerte were grouped as one area and characterized by Lecithocladium excisum.•Specimens from Kelibia and Mahdia were clumped as a single area and characterized by four parasites.•One area grouped fish form Zarzis and was correlated negatively with P. polonii and T. laticollis.•Parasites were a good biological tags.

Ten parasites were used as biological tags to discriminate juvenile and young adult areas of horse mackerel Trachurus trachurus. In total, 365 fish were examined in four zones off the Tunisian coasts, including Bizerte in the north, Kelibia and Mahdia in the center and Zarzis in the south. Discriminant analyses used to identify distinct juvenile and young adult areas of T. trachurus. Fish from Bizerte were grouped as one area and were characterized by the presence of Lecithocladium excisum. Specimens from Kelibia and Mahdia were clumped together, as a single area. The monogenean Cemocotyle trachuri, digeneans Prodistomum polonii and Tergestia laticollis and anisakid larvae were the main important species in determining the location of sampled fish from these regions. One area grouped fish form Zarzis and was correlated negatively with digeneans P. polonii and T. laticollis. These results were corroborated by comparing the parameters of prevalence and mean abundance of parasites between zones.