Anisakis simplex (s.l.) in Grey gurnard (Eutrigla gurnardus) from the North Sea: Food safety considerations in relation to fishing ground and distribution in the flesh

Abstract

Previous studies have shown that Grey gurnard from the North Sea is comparatively heavily infected with the larvae of the parasitic and potentially consumer hazardous nematode Anisakis simplex (s.l.). Especially the high abundance of Anisakis larvae in the fish flesh is of concern regarding the possible intensified utilisation of Grey Gurnard as a food resource. To gain better knowledge of the nematode burden with emphasis on abundance and distribution in the fish flesh, various Grey gurnards from 6 localities across the North Sea, each representing either western, northern or eastern fishing grounds, were examined for anisakid nematodes during summer of 2010 and 2012. The overall prevalence of A. simplex (s.l.) larvae in the gurnards from all localities (n = 188) was nearly total, i.e. only a single fish from the northernmost locality (Viking Bank) was apparently not infected. GLM-analyses revealed that catching locality had by far the strongest effect on larval infection probability, both in total (flesh + viscera) and in the fish flesh, while body size (weight) was a weak but still significant predictor of overall A. simplex (s.l.) abundance, but not in the flesh. Thus, the overall larval abundance in the gurnards from the two western localities off the east-coast of British mainland was significantly higher compared to the other catching localities. In the former localities, the overall mean abundance of A. simplex (s.l.) larvae was 35.0 ± 23.9 and 92.2 ± 87.4, and ranged from 14 to 114 and 9 to 397, respectively. It was further shown that 93.8% of the larvae infecting the fish flesh were situated in the belly flaps, i.e. the ventral portion of each flesh side or fillet, independent of catching locality and fish size. However, trimming of the fillets by removing the belly flaps may reduce the abundance in the fillets to, on an average, 0.3 larvae.