Anisakid infection in the European shag Phalacrocorax aristotelis aristotelis

A total of 100 specimens of the European shag Phalacrocorax aristotelis ari stotelis were examined for anisakid infections in the south-east North Atla ntic. The taxonomic status of the anisakid nematodes was studied by structu ral analysis using light and scanning electron microscopy. Two species, Con tracaecum septentrionale and C. rudolphii A (Nematoda: Ascaridoidea), occur red in the European shag with high values of prevalence and mean intensitie s of infection. These constitute new host records for both parasites, widen ing their known geographical distribution. Although the histopathology asso ciated with the infections indicated that the anisakids did not have the po tential to cause bird death, the parasites are capable of contributing to a nd hastening avian mortality in the case of heavily-parasitized cormorants and when stressed by xenobiotics and/or through a synergetic effect by othe r bioagressors.