Abundance and distribution of Anguillicola crassus (Nematoda) in eels Anguilla anguilla from Moulouya Estuary (Morocco)

The first record of Anguillicola crassus in Morocco was made in 1994. In 1996, none of 76 eels examined was found to be affected. Four years later, the swim-bladder parasite was well established in Moulouya Estuary on the Mediterranean coast with 50 of 114 eels examined were infected. The prevalence and intensity of Anguillicola crassus infections in the swim-bladder of the European eel Anguilla anguilla are presented. Eel samples revealed a parasite prevalence ranging between 0 and 70 %, with a variation in mean intensity of infection of between 1 and 5.33 nematodes per infected host. The abundance varied between 0 and 2.4 per examined host. The results support the hypothesis proposed by previous workers that the parasite originally entered the Moulouya estuary via the commercial trade in live eels.