Prevalence and intensity of infection of Cryptocotyle lingua (Creplin) and Diplostomum spathaceum (Rudolphi)--parasitic metacercariae of Baltic cod (Gadus morhua L.).

A parasitological investigation of Baltic cod, caught in the Bornholm Basin, showed that 1.6% were infected by C. lingua (metacercaria) and 22.5% were infected by D. spathaceum (metacercaria). Only the heavily C. lingua infected cod showed discoloured fillets due to metacercariae in the muscle. The highest intensity of infection of D. spathaceum was found in smaller cod, but only minor opaque spots were observed in the infected lenses. The low prevalence of C. lingua is supposed to be a result of the mixing of uninfected eastern cod with some infected western cod. Both cod from the eastern Baltic and part of the cod in the western Baltic are liable to be exposed to infection by D. spathaceum.