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

Abstract

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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Acknowledgements

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). https://doi.org/10.1007/s10499-016-0093-y

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Keywords

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