Sampling of individual salmon upon their return to fresh water to spawn collects information on the size, sex and age of the fish. This information feeds directly into the stock assessments used for national and international management of Scottish salmon both through the construction of stock recruitment relationships and estimation of egg deposition. Sampling of individuals can also provide information on their condition, while examination of scale samples allows their growth history to be investigated. Together with data on salmon catches and counts, these sampling records underpin adult salmon stock assessment in Scotland.