Rasmus is a freshwater ecologist with the Coastal and Freshwater Group. He is involved in both research and commercial projects in the freshwater area. Rasmus' main area of expertise is recreational fisheries management and fish ecology and behaviour. He is also completing his PhD in ecology as a part-time student while working for Cawthron.  

Fish behaviour and ecology, with a focus on migration and recruitment patterns Application of traditional fishery monitoring techniques with more recently developed tools, such as fish ear bone (otolith) microchemical analysis of hard and soft body parts and bioenergetics growth modelling, to make inferences about life history strategies in different habitats Validation and development of the use of geochemical markers in otolith to identify migratory movements and natal areas of high importance to freshwater sports fish populations Fish life-history strategy, migration and evolutionary adaptations Fish passage investigation, monitoring and solutions Recreational fisheries management and survey techniques Natural resource management