Anisakid nematode larvae in the liver of Atlantic cod Gadus morhua L. from West Greenland.

Anisakid nematode larvae occur frequently in the liver of Atlantic cod, but merely few infection data from cod in waters around Greenland exist. The present study reports the occurrence of third-stage anisakid larvae in the livers of 200 Atlantic cod caught on fishing grounds along the West coast of Greenland (fjord systems of Maniitsoq) in May, June, August and September 2017. Classical and molecular helminthological techniques were used to identify the nematodes. A total of 200 cod livers were examined, and 194 were infected with third-stage nematode larvae (overall prevalence of infection 97%) with a mean intensity of 10.3 (range between 1 and 44 parasites per fish). Prevalences recorded were 96% for Anisakis simplex (s.l.), 55% for Pseudoterranova decipiens (s.l.) and 8% for Contracaecum osculatum (s.l.). Sequencing the mtDNA cox2 from 8 out of 23 these latter larvae conferred these to C. osculatum sp. B. A clear seasonal variation was observed, with a rise in A. simplex (s.l.) and P. decipiens (s.l.) occurrence in June and August and a decline in September. The study may serve as a baseline for future investigations using the three anisakids as biological indicators in Greenland waters.