Large and old fish provide vital ecological and ecosystem service functions related to reproduction and recruitment, food web dynamics, cultural transmission of knowledge, and resilience to climate change. Despite increasing appreciation of the ecological and fisheries value of old and large fish and the availability of effective conservation management options, old age-classes continue to be systematically over-harvested. Age- and size-selective harvest can have cumulative effects resulting in age-truncation, age-class extirpation and extinction which exacerbates fisheries volatility, reduces population resilience and can alter food web structure and function. To facilitate more sustainable fisheries and ecosystem management, I suggest that longevity over-fishing be recognized and monitored as a type over-fishing to avoid. Here, I review examples, discuss and define longevity over-fishing and longevity conservation, including management approaches and policies that can be used in fisheries and aquatic ecosystem management.