Parasites of the blue shark (Prionace glauca L.), in the North-East Atlantic Ocean

A total of 159 blue sharks, ranging in length from 64 to 228 cm, was collected from the tuna drift-net fishery operating in the North-East Atlantic Ocean, and a parasite analysis conducted. The parasite assemblage consisted of three copepod species, one nematode species and four cestode species. The copepods Kroyeria lineata and Phyllothereus cornutus both occurred on the gills, while Echthrogaleus coleoptratus occurred on the skin. The third larval stage of the nematode Anisakis simplex was recorded from the lumen of both the stomach and spiral valve, but it seems likely that these specimens were a build up of parasites from consumed prey, and were not actively parasitizing the sharks. The cestodes Prosobothrium armigerum, Anthobothrium laciniatum and Platybothrium auriculatum were all recorded from the spiral valve, while Hepatoxylon trichiuri was recorded from the body cavity. All species with the exception of E. coleoptratus displayed a negative binomial distribution, although Green's Index determined that the degree of aggregation was only slight. Infection parameters varied widely among species, but the most abundant parasite was K. lineata, which was recorded from all of the sharks examined.