Long-term biological histories are key tools in forecasting responses to future ecological and environmental change. Accordingly, temporal trends of fish growth, which is a primary predictor of population productivity and fishery biomass, are important considerations in species management. We reconstructed a multidecadal (37 years) growth chronology and identified growth drivers of an iconic commercial fish species in Australia, snapper (Chrysophrys auratus). We focused on four key fishery areas in South Australia that are oceanographically and ecologically diverse. Otolith (ear stone) sclerochronology combined with a mixed-modelling approach was used to identify growth variation. Chronologies were developed at both annually and seasonally resolved scales. Environmental factors (sea surface temperature, chlorophyll-a and Southern Oscillation Index), biological performance indicators (recruitment) and anthropogenic influences (commercial catch) were assessed as individual and interactive drivers. We revealed significant temporal trends and inter-regional variation in snapper growth that was driven by intrinsic and extrinsic factors. This study highlights an effective and inexpensive method for exposing long-term biological trends and responses to changing environments. This will enable informed ecological predictions to mitigate risk and shape sustainable management of an important natural resource and industry.