Year-round no-take marine protected areas (MPAs) can enhance conservation of exploited species and biodiversity overall. MPAs have the potential to sustain living marine resources and their support systems at genetic, population-community, ecosystem, and landscape levels. From a fisheries perspective they can protect spawning and nursery areas of key species, maintain age structure (retain older, proportionately more fecund individuals), protect key habitats, and reduce bycatch. MPAs are used sporadically in management of fisheries and are generally based on predicted responses for populations of exploited taxa. However, identification of representative, rare, and high diversity areas of temperate and boreal marine systems, especially on outer continental shelves, is still in its infancy. There is information available from both the scientific literature and from fishers on the life history and behavior of economically important species, on species assemblage patterns, and on physical structure of the marine environment. Such information could be used as a starting point for identifying areas of particular importance to populations or communities of fishes and for the conservation of diversity at the regional scale. Identification of such areas could serve as a basis to design an experimental network of MPAs. Such MPAs, designated for the purpose of maintaining or developing sustainable fisheries, must explicitly be designed within an experimental context, maintaining flexibility for changes in regulations as new information becomes available. Monitoring change in exploited and non-target populations (intra- and inter-guild), habitat complexity indices, and diversity of sentinel taxa (for assessing maintenance of diversity) will be needed to provide feedback to assess the efficacy of MPAs and to recommend changes in the regulatory framework.