Abstract
Mortality at sea is believed to be a major cause of progressive decadal declines in numbers of Atlantic salmon returning to rivers across Scotland. Different salmon populations may be distributed differently at sea. An ability to map out the distributions of river populations at sea would aid planning of new marine developments and management of existing marine activities to reduce potential impacts on particularly important salmon stocks. Recently, it has been possible to capture groups of young salmon at sea off the east coast of Scotland as they migrate to high seas feeding grounds. This project tested whether it is possible to sample the genetic constitution of such fish to work out which rivers they came from. In particular, it was investigated whether it is possible to distinguish fish from among the large east coast rivers of Scotland, which has not been feasible with genetics methods used previously. Unfortunately, even with more advanced genetics methods used in this project it was feasible only to distinguish salmon from certain rivers and groups of rivers from one another.