Quality issues related to the presence of the fish parasitic nematode Hysterothylacium aduncum in export shipments of fresh Northeast Arctic cod (Gadus morhua)

Miguel Bao,Paolo Cipriani,Lucilla Giulietti,Natalia Drivenes,Arne Levsen

doi:10.1016/j.foodcont.2020.107724

Miguel Bao, Paolo Cipriani + Show 3 more

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https://doi.org/10.1016/j.foodcont.2020.107724

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Journal: Food Control	Publication Date: Oct 27, 2020
Citations: 9	License type: cc-by

Affiliation: Norwegian Institute of Marine Research

Abstract

The parasitic nematode Hysterothylacium aduncum commonly occurs in many fish species in the Northeast (NE) Atlantic. The parasite is considered non-pathogenic to humans. During spring and summer of 2018, lots of head-on eviscerated fresh NE Arctic cod (Gadus morhua) were shipped from Norway to Spain for commercialization. At arrival, the presence of lively roundworms (i.e. H. aduncum) in the transporting boxes was noticed. Consequently, fish lots were rejected causing substantial monetary losses to all involved parties. As part of the hazard assessment process, the epidemiology of H.aduncum in cod, NE Arctic saithe (Pollachius virens) and NE Arctic haddock (Melanogrammus aeglefinus) fished off West-Finnmark, Norway, was studied. Parasites were morphologically and molecularly identified to species level. Additionally, the viability of H. aduncum was assessed by simulating the conditions that prevail during transport of fresh cod to European market. The infection values of L4 larval stage or adult H. aduncum in the digestive tract of fish were highly variable, ranging from 100% prevalence with mean abundance (range) 238 (10–1092) in cod to 27% prevalence with mean abundance (range) 1 (0–22) in haddock. Fishing season was identified as most important explanatory factor for parasite abundance. Infection levels were higher during winter and early spring, and lower during late spring. Infection peaks of H. aduncum in the three fish species seemed to coincide with heavy predation on spawning capelin (Mallotus villosus) during winter and early spring. Thorough evisceration seems to remove most of the nematodes from the fish. However, parasites may remain hidden within the head cavities where they can stay alive and active under regular transport conditions for at least 14 days. Hysterothylacium aduncum can be completely removed from the product by evisceration, beheading and rinsing the fish prior to shipping. Alternatively, thorough cleaning or completely removal of the gills and pharynx may be considered.

Highlights

Parasitic nematodes commonly known as “kveis” in Norway, often occur in visceral organs and muscle of many Northeast (NE) Atlantic commercially important marine fish species, such as Atlantic cod (Gadus morhua), saithe (Pollachius virens) and haddock (Melanogrammus aegle finus) (Bao et al, 2020; Gay et al, 2018; Levsen et al, 2018; Pierce et al, 2018; Strømnes & Andersen, 1998)
Hysterothylacium sp. subsamples were morphologically assigned to adult/L4 or L3 of H. aduncum
The life cycle of H. aduncum occurs in the marine ecosystem and includes predatory fishes, such as gadoids, as final hosts, where adults reproduce within the digestive tract (L4 larvae may be present) and die (Berland, 1961; Køie, 1993)

Summary

Introduction

Parasitic nematodes commonly known as “kveis” in Norway, often occur in visceral organs and muscle of many Northeast (NE) Atlantic commercially important marine fish species, such as Atlantic cod (Gadus morhua), saithe (Pollachius virens) and haddock (Melanogrammus aegle finus) (Bao et al, 2020; Gay et al, 2018; Levsen et al, 2018; Pierce et al, 2018; Strømnes & Andersen, 1998). Besides the presence of anisakids in fish, the occurrence of other ascaridoid nematode belonging to the family Raphidascarididae, i.e. Hysterothylacium aduncum is very common (Klimpel & Rückert, 2005). Hysterothylacium aduncum uses fish as final host, whilst Anisakis spp., Pseudoterranova spp. and Contracaecum spp. use cetaceans, seals and seals/fish-eating birds, respectively in their life cycle (Berland, 2006). H. aduncum can heavily infect many fish species in NE Atlantic waters (Berland, 1961; Klimpel, Kleinertz, Hanel, & Rückert, 2007; Klimpel & Rückert, 2005), and the presence of larval or adult specimens may heavily reduce the aesthetical appeal of fish products, potentially causing socioeconomic problems to the fishing industry

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