Geographical variations in abundance of larval anisakine nematodes in Atlantic cod (Gadus morhua) and American plaice (Hippoglossoides platessoides) from the Gulf of St. Lawrence

Abstract

Atlantic cod (Gadus morhua) and American plaice (Hippoglossoides platessoides) collected from various sites in the Gulf of St. Lawrence (NAFO divisions 4RST) were examined for larval anisakine nematodes in 1990 and 1992. Sealworm larvae (Pseudoterranova decipiens) were more abundant in southern Gulf (4T) than in northern Gulf (4RS) cod and plaice. The heaviest sealworm infections occurred in fish from St. Georges Bay, Nova Scotia. Abundance of P. decipiens in cod from St. Georges Bay was significantly lower in 1992 than in 1990. Anisakis simplex and Contracaecinea (Contracaecum/Phocascaris spp.) were most abundant in cod from the northern Gulf. American plaice were not heavily infected with A. simplex or Contracaecinea. Geographical and temporal variations in abundance of larval anisakine nematodes in fish may reflect distribution and abundance of the phocid and cetacean definitive hosts and variations in water temperatures.