No-take marine reserves (NTMRs) provide hope that local carrying capacity may be partially restored if reserves are protected long enough. How long is long enough? We assess the duration of protection required for populations of large predatory reef fish in marine reserves to attain new steady states. We monitored biomass of large predatory fish in two marine reserves at Sumilon and Apo Islands, Philippines, almost annually for 26 years (1983-2009), and fit a logistic model to the data. As duration of reserve protection increased, biomass of predatory fish approached an asymptote, although the models suggest that 20-40 years of protection is required to attain new steady states. Thus, for local carrying capacity to be rebuilt, no-take protection must be effective on decadal timescales.