Temporal and spatial variations in lice numbers on salmon farms in the Hardanger fjord 2004-06

P.A. Heuch, R.S. Olsen, R. Malkenes, C.W. Revie, G. Gettinby, M. Baillie, F. Lees, B. Finstad, Fisheries and Aquaculture Industry Research Fund (Funder), Norwegian Research Council (Funder)

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)
110 Downloads (Pure)


The long and narrow Hardanger fjord in western Norway has a high density of salmon farms and has had severe salmon lice, Lepeophtheirus salmonis, problems. In the years 2004-06, salmon lice numbers were recorded in selected salmon farms in the fjord as part of a larger research project. Most farm sites participated in a strategic control programme and were deloused between November and January in each year. The aim of the programme was to achieve a mean abundance of <0.3 adult female lice at this time and to minimize the infection pressure on wild smolts in the spring. Dedicated teams carried out detailed counting of lice on farmed fish in April-September each year. Temperature conditions were fairly similar throughout the fjord and amongst years, but wide variations in salinities were observed. The two innermost zones, B and C, had the lowest lice mean abundances, whereas the outermost zones, D and E, consistently had more lice. General linear model analyses showed that differences in adult female lice abundance between the zones were associated with differing levels of salinity and emamectin benzoate treatments strategically administered. Mean fish weight was significantly positively correlated with mean abundance of adult female lice.
Original languageEnglish
Pages (from-to)89-100
Number of pages12
JournalJournal of Fish Diseases
Issue number1
Publication statusPublished - 31 Jan 2009


  • abundance
  • epidemiology
  • Lepeophtheirus salmonis
  • Norway


Dive into the research topics of 'Temporal and spatial variations in lice numbers on salmon farms in the Hardanger fjord 2004-06'. Together they form a unique fingerprint.

Cite this