Lake IJsselmeer is a former estuary in the Netherlands that has been cut off from the sea in 1932. Excessive fishing effort, ongoing declines in landings and low revenues indicate that 75 years of fishery have not been sustainable in terms of socio-economical and ecological stability or avoidance of over-exploitation, despite measures aiming at reductions in fishing effort throughout the management history. We review the management history with a focus on how responsible fisheries management depends on time scales of management decisions, in comparison to time scales of fish population dynamics, and ecological changes. Management actions to improve sustainability have been generally implemented with considerable delays and in small steps, to avoid short-term losses in revenues. These actions turned out to be insufficient, as their potential impact was both inadequate and counteracted over time by technical advances in fisheries and by unforeseen ecological changes.