Fish catch data comprising species identification, abundance and length. Weight, sexual maturity and age are also recorded for a sub-sample of the total catch. The data were obtained from a number of sea lochs in the Forth of Lorne and the Isle of Mull, north west Scotland, typically on a monthly basis between 1967 and 1971. The data were obtained from fish caught in a number of ways including trawls behind small boats and vessels, by divers, and from individuals on beaches. They do not include samples collected using bottom or mid-water otter type trawls (Seine, Agassiz or beam). Collectively, these data form an unique insight into the fish population history of this region. The original data were collected under the overall supervision of John Gordon, at the Scottish Marine Biological Association (SMBA).