Infestation of cod (Gadus morhua L.) with larvae of codworm (Terranova decipiens Krabbe) and herringworm, Anisakis sp. (Nematoda, Ascaridata), in North Atlantic and Arctic waters.
Nearly 5,300 Gadus morhua collected from the North Atlantic and Arctic during 1971-73 were examined for larvae of Terranova decipiens and Anisakis sp. The nematode burdens showed strong positive correlations with fish size and age. T. decipiens was very common in Icelandic and Faroe Plateau cod but virtually absent from cod from Greenland, Faroe Bank and Arcto-Norwegian fisheries. Larvae of Anisakis sp. were present in all the stocks examined, most commonly in the Arcto-Norwegian stock of which 95% of fish were infested (mean burden 10/fish). The incidence in cod from the North Atlantic was 70 to 82% (mean 2/fish). Differences in the distribution of the 2 species are discussed in relation to the distribution of the definitive hosts. The use of T. decipiens as a biological tag is also considered.