Long-term continuous datasets that record fishery catch are key to predicting and managing changes in fisheries. Unfortunately, long-term datasets are rare for recreational fisheries, which hinders our ability to understand long-term changes within these fisheries. Here we use several unconventional long-term datasets, including tournament and tagging program data, to assess changes in catch composition over time in the Australian east coast marlin fishery. We found significant changes to the species and size composition of species within the fishery over time. In the 1930s, catch was solely comprised of striped (Kajikia audax) and black (Istiompax indica) marlin. Black marlin proportionally dominated the fishery in the 1940s to 1980s, but the proportions of blue (Makaira nigricans) and striped marlin increased significantly from the 1980s until present. Currently, the fishery is comprised of primarily striped and black, and to a lesser extent blue marlin. Declines in the mean weight of black and striped marlin were also evident from the 1930s to 1980s. Technological advances improving offshore access may have driven changes in species composition. Our results demonstrate a potential change in technology and gear reshaping species composition within a fishery. This highlights how recreational fisheries, particularly those offshore, have changed with the technology over time, and the potential for future technological to dramatically alter recreational fisheries globally.