Two kinds of approaches have been used to assessing conservation and fisheries-related effects of marine protected areas (MPAs) : (i) statistical modelling based on fiel data and (ii) mathematical modelling quantifying the consequences of MPAs on the dynamics of populations, communities, and fisheries. Statictical models provide a diagnostic on the impact od MPAs on the ecosystem and resources; they are also needed for devising and assessing sampling designs for monitoring programs. Dynamics models enable exploration of teh conseqences of MPA designs ans other management policies. We briefly review how each of these approaches has been implemented up to now in the literature and identify potential indicators of MPA effects that can be obtained from each approach to provide scientific advice for managers. Methodologicals gaps that impede the assessment of MPA effects and the constryction of appropirate indicatoes are the discussed, and recent developments in the respect are presented. We finally propose ways to reconcile the two approaches based in their complementarity to derive suitable indicators to support decision making. In this respect, we suggest in addition that MPA managers should be associated from the beginning to the design ans construction of indicators.