Application of real-time PCR for specific detection of Lepeophtheirus salmonis in fluid samples from lumpfish (Cyclopterus lumpus) stomachs


The Norwegian Food Safety Authority recently stated that stomach flushing is in violation of the Animal Welfare Act. The objective of our research was to develop a genetic method for the routine identification of Lepeophtheirus salmonis in stomach fluid samples taken through the mouth of lumpfish. The established method was based on a previously published real-time PCR assay targeting the mitochondrial cytochrome oxidase I (mtCOI) gene in L. salmonis. Lumpfish were fed with L. salmonis, then captured upon ingestion and subsequently transferred to an incubation tank. The method was used to test 62 fluid samples collected during the first, second and third days post L. salmonis consumption. No DNA extraction or purification was used prior to the real-time PCR. The results were compared with visual examination subsequent to dissection. Visual identification was able to identify 51 L. salmonis (82%) whereas real-time PCR was able to detect 59 L. salmonis (95%) out of the 62 examined samples. The results indicate that real-time PCR assays can be used for specific detection of L. salmonis in fluid samples from the stomach of lumpfish. Furthermore, our study demonstrates that the PCR assay offers a reliable non-lethal alternative to dissection or stomach flushing and the subsequent visual identification of L. salmonis.

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  1. Costello MJ (2009) The global economic cost of sea lice to the salmonid farming industry. J Fish Dis 32:115–118

    Article  PubMed  Google Scholar 

  2. Deady S, Varian SJA, Fives JM (1995) The use of cleaner-fish to control sea lice on two Irish salmon (Salmo salar) farms with particular reference to wrasse behaviour in salmon cages. Aquaculture 131:73–90

    Article  Google Scholar 

  3. Dingemanse NJ, Barber I, Wright J, Brommer JE (2012) Quantitative genetics of behavioural reaction norms: genetic correlations between personality and behavioural plasticity vary across stickleback populations. J Evol Biol 25:485–496

    CAS  Article  PubMed  Google Scholar 

  4. Imsland AK, Reynolds P, Eliassen G, Hangstad TA, Foss A, Vikingstad E, Elvegård TA (2014) The use of lumpfish (Cyclopterus lumpus L.) to control sea lice (Lepeophtheirus salmonis Krøyer) infestations in intensively farmed Atlantic salmon (Salmo salar L.). Aquaculture 424-425:18–23

    Article  Google Scholar 

  5. Imsland AK, Reynolds P, Eliassen G, Mortensen A, Hansen ØJ, Puvanendran V, Hangstad TA, Jónsdóttir ÓDP, Emaus P-A, Elvegård TA, Lemmens SCA, Rydland R, Nytrø AV, Jonassen TM (2016) Is cleaning behaviour in lumpfish (Cyclopterus lumpus) parentally controlled? Aquaculture 459:156–165

    Article  Google Scholar 

  6. Mattilsynet (2016) Mageskylling av rognkjeks er i strid med dyrevelferdsloven. Cited 21 Mar 2016

  7. McBeath A, Penston M, Snow M, Cook P, Bricknell I, Cunningham C (2006) Development and application of real-time PCR for specific detection of Lepeophtheirus salmonis and Caligus elongatus larvae in Scottish plankton samples. Dis Aquat Org 73:141–150

    CAS  Article  PubMed  Google Scholar 

  8. Skiftesvik AB, Blom G, Agnalt A-L, Durif CMF, Browman HI, Bjelland RM, Harkestad LS, Farestveit E, Paulsen OI, Fauske M, Havelin T, Johnsen K, Mortensen S (2014) Wrasse (Labridae) as cleaner fish in salmonid aquaculture—the Hardangerfjord as a case study. Mar Biol Res 10:289–300

    Article  Google Scholar 

  9. Treasurer JW (2002) A review of potential pathogens of sea lice and the application of cleaner fish in biological control. Pest Manag Sci 58:546–558

    CAS  Article  PubMed  Google Scholar 

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The study was financed by the Aquaculture Research Station of the Faroes. We would like to thank Ingibjørg Joana Mortensen, Faroese Veterinary Service, Faroe Islands, Birna Højsted and Sólvá Samuelsen, Aquaculture Research Station of the Faroes, as well as Julia Frank and Malin Wollens, University of Applied Sciences, Bremerhaven, Germany, for their practical assistance.

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Correspondence to Jonhard Eysturskarð.

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Eysturskarð, J., Johannesen, Á. & Eliasen, K. Application of real-time PCR for specific detection of Lepeophtheirus salmonis in fluid samples from lumpfish (Cyclopterus lumpus) stomachs. Aquacult Int 25, 969–973 (2017).

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  • Lumpfish (Cyclopterus lumpus)
  • Stomach flushing
  • Lepeophtheirus salmonis
  • Real-time PCR