Overfishing is a mounting threat to marine ecosystems and food security worldwide. Recreational fisheries are poorly understood and pose governance challenges due to the scarcity of monitoring data. The impact of recreational spearfishing on eastern blue groper (Achoerodus viridis) and grey nurse shark (Carcharias taurus) in Australia was analysed by assessing a chronology of spearfishing publications for historical, ecological and social data. Reported captures of blue groper declined by 90% from 1952–1967. Grey nurse shark captures also declined. Interestingly, early warnings of declines for both species emerged from the spearfishing community 17 and 19 years, respectively, before protection. While recreational fishers may have serious impacts on vulnerable fish species, they could also play a vital role in conservation and advocacy. This highlights the importance of reciprocal communication between fishers, scientists and governments for managing and detecting declines in vulnerable species.