Population genomics and parentage assignment in sea trout

The aims of this study are: 1) to evaluate fitness (in terms of reproductive success and offspring survival) of wild sea trout, and 2) to study genomic differences between wild sea trout populations across Southern Norway and search for gene-environment interactions that drive local adaptation. We will use electrofishing to catch juvenile and adult trout in (spawning) streams and collect length and weight measurement and take DNA and scale samples. Through DNA analysis, juveniles can be assigned to adult sea trout and allows to investigate parent-offspring relations in traits related to reproductive succes and survival. Prior to data collection, fish will be anaesthetized to reduce the stress and not affect survival and health of individuals. Fish will be monitored for 10-15 minutes prior to release. 8 different streams will be sampled and from each stream 50-55 adult fish will be sampled in September-October (2016 and 2017) and 150 juvenile fish will be sampled in July and August (2017). In order to study the adaptive mechanism in marine fish at genomic and behavioural level, it is necessary to study wild populations. The estimation of individuals used in this study represents the minimum number of individuals we consider necessary to obtain biological meaningful results. Furthermore, to reduce the stress and secure a healthy release of fishes, we will use an anaesthetic. The anaesthetic ensures that handling time for taking measures will be decreased to a minimum.