Abstract
The project has access to two unique long-term time series of Capture-Mark-Recapture (CMR) data on brown trout from Mjøsa (37 years) and pike from Windermere in N-W England (51 years). Both species involved are important game fishes that are under harvesting throughout Europe. By applying modern CMR statistical techniques on these data, the project aims at attaining an increased and more detailed understanding of population dynamics of these two top-predators. In particular, the project will use very recently developed techniques that provide separation of natural mortality and fishing mortality. The two predatory species differ in a number of important biological features (habitat use, life cycle and hunting strategy). Further, both systems have good data on environmental changes, food abundance and fishing pressures during the entire period. Effects of these important variables on demographic processes may therefore be tested. Due to the interspecific differences in important biological features, the project expects to detect a broad spectrum of demographic responses to the changes in environmental conditions and harvesting regimes. The results from the project will provide essential information for the construction of adaptive management programs not only for the studied systems, but also for predatory freshwater fish in general.
Norway