Ecological parasitology encompasses studies of the distribution and abundance of parasites in different hosts through space and time, and the factors influencing the interactions between host and parasite on both an individual scale and at the population level.
Our research within this field is, to some extent, based on management problems. One central issue is the relationship between overpopulation and high parasite infections in lake dwelling fish, and in the extension of this, we conduct long term studies of the effects of stock manipulations in the form of mass removal of fish through intensive fishing programmes.
Since most parasites are transmitted to fish via prey organisms, we also work in the intersection between feeding ecology and parasitology to elucidate the mechanisms behind changes in infection patterns within and between years, as well as through the lifespan (ontogeny) of the fish hosts, and between different localities. Likewise, parasite communities are employed as biological tags in analyses of intra- and interspecific food niche segregation in fish populations.
Over the last few years, we also have had a strong focus on the most serious threat against Norwegian stocks of Atlantic salmon, the small ectoparasite Gyrodactylus salaris (“the salmon killer”). Our studies are located to River Skibotnelva and River Signaldalselva which are the only two infected rivers in the counties of Troms and Finnmark, and mainly concern the role of anadromous Arctic charr as a host to this serious parasite.
Finally, we address parasite problems in the marine environment, mainly related to fish farming. Key words here are salmon lice (Lepeophtheirus salmonis) on both wild and farmed salmonids, and the incidence of parasites in farmed cod.