Networks of marine protected areas (MPAs) are being increasingly implemented worldwide as conservation management tools. We report here on MPA effectiveness using a 16-year long ROV monitoring program spanning 24 MPAs across California’s MPA network. Our estimates show that MPA protection has a positive effect on the abundance of four demersal fish species with wide geographic distributions across the MPA network. We also demonstrate that there have been regional recoveries in abundance for these species outside of the MPAs. Our approach highlights the utility of remotely operated vehicles (ROVs) to support timely reporting on the effectiveness of MPA networks with quality monitoring data.