Evolutionary ecology
EvoFish in media

Is fish farming driving evolution in fish parasites?

Mathias Stølen Ugelvik is studying host-parasite interactions using Atlantic salmon and salmon louse as the model system. The latest study, published in the Journal of Evolutionary Biology, shows that lice in an area with fish farming have evolved to become more virulent, as predicted by the theory. Now the study has been also discussed by The Scientist!

Lakselus i ulike stadier, tatt på villaks i Bolstadfjorden
Lakselus i ulike stadier, tatt på villaks i Bolstadfjorden
Dag Hellesund

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Mathias Stølen Ugelvik, together with Arne Skorping from EvoFish, ex-EvoFisher Olav Moberg, and Adèle Mennerat from TEG, has published a paper in the Journal of Evolutionary Biology that documents how salmon lice sampled from wild hosts in unfarmed areas and from farmed hosts displayed different traits related to virulence. In particular, they showed that lice from farmed hosts were more virulent, causing more skin damage and loss of growth. Intriquingly, this is exactly as expected when a parasite is adapting to prospects of easier transmission (farming greatly increases the availability of hosts) but shorter life span (farmers don't like salmon lice)!

These exciting results also caught attention of The Scientist. In the piece "Does Farming Drive Fish Disease?", the journalist Claire Asher discusses how intensive aquaculture favors increasingly virulent forms of certain fish-infecting parasites and pathogens.


Ugelvik, M. S., A. Skorping, O. Moberg, and A. Mennerat. 2017. Evolution of virulence under intensive farming: Salmon lice increase skin lesions and reduce host growth in salmon farms. Journal of Evolutionary Biology. doi: 10.1111/jeb.13082.