The group uses stock-recruitment relationships derived from data from a number of rivers across Europe. Various models with differing levels of complexity are being evaluated, taking into account factors such as habitat variation, occurrence of lakes, and migration obstacles. The capacity of index rivers to be representative of larger areas with sparse information is also being examined.
There is a growing need to develop assessment methods for sea trout populations. Establishing biological reference points is a prerequisite for being able to assess status of populations, and ways of estimating BRPs from population models – based on for example stock-recruitment relationships or estimated pristine abundance levels – are being examined.