Euphausiids as intermediate hosts of Anisakis simplex in the St. Lawrence estuary

To determine abundance of larval Anisakis simplex in euphausiids of the St. Lawrence estuary, Meganyctiphanes norvegica and Thysanoessa raschii were c ollected at seven sites from the mouth of the Saguenay River to Bale des Ou tardes. Larvae were removed from euphausiids by means of a modified Baerman n apparatus filled with a pepsin-HCl digest solution. Abundances of larvae in euphausiids ranged from 0 to 58.2 x 10(-5). Larvae (N = 100) were in the third stage (bearing one cuticle) or moulting from the second stage to the third stage (bearing two cuticles). Euphausiids, particularly T. raschii, which represented 98% of the total euphausiids sampled, are important inter mediate hosts of A. simplex in the St. Lawrence estuary. These data indicat e the importance of the St. Lawrence estuary as an enzootic zone for A. sim plex and thus a valuable area to study the biology and the transmission of this parasite.