Helminth parasites of the chub mackerelScomber coliasoff the Tunisian coast and their use in stock discrimination

Abstract

AbstractNine helminth parasites were used as biological tags to discriminate diverse areas ofScomber coliasGmelin, 1789. During three seasons, a total of 369 fish were examined in four zones off the Tunisian coast, including Bizerte in the north, Kelibia and Mahdia in the centre and Zarzis in the south. Discriminant analyses were used to identify distinct areas ofS. colias. Fish from Bizerte were grouped as one area and were correlated negatively with the monogeneanGrubea cochlearand the digeneanLecithocladium excisum. Specimens from Kelibia and Mahdia were grouped together and were characterized by the ectoparasitePseudokuhnia minorand by endoparasitesProdistomum orientalis, Monascus filiformisand anisakid larvae. Fish from Zarzis were grouped as one area and were positively correlated with the monogeneanG. cochlearand the digeneanL. excisum. These results were corroborated by comparing the prevalence and mean abundance of parasites among zones. Results of other discriminant analyses used for the classification ofS. coliasbetween localities after pooling specimens from the central areas of Kelibia and Mahdia also allowed the identification of three distinct areas: one in the north, correlated negatively withG. cochlearandL. excisum;one in the centre, characterized byP. minor, P. orientalis, M. filiformisand anisakid larvae; and one in the south, from Zarzis, characterized byG. cochlearandL. excisum. Results of comparisons of infection parameters between seasons and those of seasonal discrminant analyses showed a seasonal stability of communities from the northern and the southern areas. Specimens from the central regions showed variability between seasons, suggesting migratory movements.