Rasmus is a freshwater ecologist interested in research that betters our understanding of the structure and functioning of freshwater ecosystems. His PhD focussed on the quantification of interaction strengths within a stream food web, assessing the effects of top-down and bottom-up pressures upon these interactions. This study included all components of the food web including algae, invertebrates, fish and their respective diets. As Head of Fisheries Research at Game & Wildlife Conservation Trust, the catchment wide study of the salmon and trout populations in the River Frome in Dorset, UK has been at the centre of Rasmus’ work over the last number of years.
Among the more specific themes of this research are assessing the importance of habitat and inter- and intraspecific competition between salmonids and the impact there of on survival and life history choices. As lead partner on two large grants the group’s work on the Frome has been extended to other rivers and, in collaboration with international partners, the results from the Frome put in a wider context. The majority of this research involves the use of tagging technology (PIT, acoustic and data storage tags) enabling assessment of migration strategies and loss rates in fresh- and saltwater and factors affecting this at the level of both the individual and the population.