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Parasitology Research

, Volume 114, Issue 1, pp 257–264 | Cite as

Sealworm (Pseudoterranova decipiens) infection in grey seals (Halichoerus grypus), cod (Gadus morhua) and shorthorn sculpin (Myoxocephalus scorpius) in the Baltic Sea

  • Sven-Gunnar Lunneryd
  • Maria Kristina Boström
  • Paul Eric Aspholm
Original Paper

Abstract

The anisakid nematode Pseudoterranova decipiens, known as the sealworm or cod worm, can infect the flesh of several fish species. The parasite causes cosmetic problems for the fish industry and can cause abdominal discomfort if consumed by humans. There are only scattered studies on the abundance or distribution of the sealworm in fish and seals in the Baltic Sea. To remedy this situation, the extent of sealworm infection was investigated in cod (Gadus morhua) and shorthorn sculpin (Myoxocephalus scorpius) collected along the Swedish coast. A relative presence of the sealworm was also investigated in samples from grey seal (Halichoerus grypus) stomachs. Up to 100 % of the fish were infected in some of the areas. Sculpin were generally worse infected than cod, both in abundance and prevalence of parasites. General linear models showed a significant correlation between the number of seals in an area and the prevalence of sealworms in cod. There was a sharp decrease of infected fish in areas with salinity lower than 7 ‰. Even though the northern Baltic proper and the southern Bothnian Sea have a high number of grey seals, only one sealworm was found in a sculpin in that region, and none in cod. In grey seal stomachs the sealworm was only found in samples from the central Baltic proper; further north, all anisakid nematodes identified in seals were Contracaecum osculatum. The results indicate that seal presence drives the distribution in the southern parts of the Baltic and that low salinity, or some other variable which correlates with salinity, limits the distribution in the northern part.

Keywords

Baltic Sea Cod Grey seal Pseudoterranova Sealworm Sculpin 

Notes

Acknowledgments

We thank Olle Karlsson (Swedish Museum of Natural History) for providing seal haul-out data, Karl Lundström for collecting nematodes from the seal stomachs and Massimiliano Cardinale for analytical support. Also, thanks to the people who assisted in collecting fish over the years, both university students and commercial fishermen. This study was financed by the Swedish Agency for Marine and Water Management, the Seals and Fisheries Program and Nybelins Fund. All work was carried out with approved applications submitted to the Ethical Board on Animal Experiments.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Sven-Gunnar Lunneryd
    • 1
  • Maria Kristina Boström
    • 1
  • Paul Eric Aspholm
    • 2
  1. 1.Department of Aquatic ResourcesSwedish University of Agricultural SciencesLysekilSweden
  2. 2.Bioforsk-Norwegian Institute for Agricultural and Environmental ResearchFrederik A. Dahls vei 20Norway

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