Lakseopdrætsanlæg. Foto: Colourbox.

PhD defence on lice management in salmon aquaculture

Wednesday 12 Feb 20


Ken Haste Andersen
Professor, Head of Section
DTU Aqua
+45 35 88 33 99

On 21 February 2020, Tróndur Kragesteen will defend his PhD thesis at DTU, Lyngby.

PhD Student Trondúr J. Kragesteen, DTU Aqua has investigated how to optimally manage lice in open sea fish farming from a farmer's perspective. Sea lice, which are small ectoparasitic copepods, harm both farmed and wild salmon and have been a persistent plague for more than half a century. Controlling lice levels in aquaculture requires treatments of which most are harmful to the local environment and furthermore are expensive.

Tróndur Kragesteen has developed a bio-economic model framework analyzing the profitability of different lice management strategies. The model shows e.g. that farm networks obtain the lowest number of treatments and highest profitability by adapting a relatively low treatment threshold, whereas more isolated farms benefit from putting off the treatment until the abundance of lice is higher. The general conclusion of the PhD thesis is that idealized salmon farm networks profit the most by keeping a low lice level and concurrently having a minimal impact on the environment.

In his PhD project, Tróndur Kragesteen also has simulated how sea lice grow and disperse—with the Faroe Islands as a study area. The results show that lice can end up in the other end of the Faroese archipelago 120 km away from their starting point.

The bio-economic model framework needs further development, Tróndur Kragesteen concludes in his thesis, but is has the potential for becoming a useful tool for authorities and fish farmers in the development of optimal management strategies towards sea lice at local, regional and national levels. 

About the PhD defence

Tróndur Kragesteen will defend his PhD thesis "Lice Management in Salmon Aquaculture, Using the Faroe Islands as a case site" on Friday 21 February 2020 at 13.00. The defence takes place at DTU, Anker Engelundsvej 1, 2800 Kgs. Lyngby, in building 101, meeting room S01.


  • Principal supervisor: Professor Ken Haste Andersen, DTU Aqua
  • Co supervisor: Professor Andre W. Visser, DTU Aqua
  • Co supervisor: Oceanographer Knud Simonsen, Fiskaaling


  • Professor Niels Lorenzen, DTU Aqua
  • Dr. Alexander Murray, Marine Scotland Science, UK
  • Researcher Anne Dagrun Sandvik, Institute for Marine Research, Norway

The thesis

A copy of the thesis “Lice Management in Salmon Aquaculture, Using the Faroe Islands as a case site” is available for reading at DTU Aqua. Please contact Rikke Hansen,
24 NOVEMBER 2020