Evolution of salmon lice in response to control measures
Salmon lice are a major pest of salmon farms in Norway. Salmon lice are an ectoparasitic crustacean that attach themselves to fish and feed on the skin and blood of their host. On salmon farms, infestations can become severe with impacts on animal welfare and productivity. Moreover, the large number of lice on farms can spillover to the wild salmon population, causing much higher lice burden than this population would otherwise support.
Given these impacts, salmon farmers are required to control lice on their farms, and there are a whole range of control techniques they employ. This project was part of a much larger project headed up by Nick Robinson at NOFIMA. The larger project looks to develop new methods of control. Our sub-project was tasked with examining the risk that Salmon lice might rapidly adapt to the new control methods.
Progress
This project is well underway. We were fortunate enough to recruit the talented Andrew Coates as the postdoc on the project. Andy rapidly pulled together everything that was known about the complex life-history of these lice (which was quite a lot) and developed a stage-structured population model. We then threaded into that a genetic model, giving a genetic basis to various life-history traits. We then threaded space into the model, using a previously-developed connectivity matrix. The result was a spatially-explicit metapopulation model in which lice populations could evolve.
This model did a pretty good job of recapitulating the rapid evolution of resistance to chemical controls seen during the early part of this century. The model also showed that evolution of resistance was faster in some areas than others; purely as a result of the high connectivity between farms in these areas.
The model is ready to receive details of the new control methods from the broader project, but in the meantime we are extending the model to ask general questions about how the evolution and spread of resistance might best be managed.
Selected publications
Robinson, Nicholas. A., Robledo, Diego, Sveen, Lene, Daniels, Rose. Ruiz, Krasnov, Aleksei, Coates, Andrew, Jin, Ye. Hwa, Barrett, Luke. T., Lillehammer, Marie, Kettunen, Anne. H., Phillips, Ben. L., Dempster, Tim, Doeschl‐Wilson, Andrea, Samsing, Francisca, Difford, Gareth, Salisbury, Sarah, Gjerde, Bjarne, Haugen, John‐Erik, Burgerhout, Erik, Dagnachew, Binyam. S., Kurian, Dominic, Fast, Mark. D., Rye, Morten, Salazar, Marcela, Bron, James. E., Monaghan, Sean. J., Jacq, Celeste, Birkett, Mike, Browman, Howard. I., Skiftesvik, Anne. Berit, Fields, David. M., Selander, Erik, Bui, Samantha, Sonesson, Anna, Skugor, Stanko, Østbye, Tone‐Kari. Knutsdatter, Houston, Ross. D. (2022). Applying genetic technologies to combat infectious diseases in aquaculture Reviews in Aquaculture raq.12733.
Coates, Andrew, Robinson, Nick, Dempster, Tim, Samsing, Francisca, Johnsen, Ingrid, Phillips, Ben. L (2022). A metapopulation model reveals connectivity-driven hotspots in treatment resistance evolution in a marine parasite ICES Journal of Marine Science. fsac202.
Dempster, T., Overton, K., Bui, S., Stien, L.. H., Oppedal, F., Karlsen, Ø, Coates, A., Phillips, B.. L., Barrett, L.. T. (2021). Farmed salmonids drive the abundance, ecology and evolution of parasitic salmon lice in Norway Aquaculture Environment Interactions. 13: 237–248.
Coates, Andrew, Phillips, Ben. L., Bui, Samantha, Oppedal, Frode, Robinson, Nick. A., Dempster, Tim (2021). Evolution of salmon lice in response to management strategies: a review Reviews in Aquaculture. 13: 1397–1422.
Coates, Andrew, Johnsen, Ingrid. A., Dempster, Tim, Phillips, Ben. L. (2021). Parasite management in aquaculture exerts selection on salmon louse behaviour Evolutionary Applications. 14: 2025–2038.