This metadata record documents the size frequency surveys for PISCO subtidal community surveys. Size frequency sampling consists of recording the number and size of target invertebrate species (urchins of the genus Strongylocentrotus and abalone of the genus Haliotis). Indivduals are encountered and recorded either as part of normal swath surveys, or during random swims anywhere within the survey site. Subtidal community structure surveys are conducted annually at all sites during the summer or early fall, and quantify substrate type and relief, benthic cover, abundance of major groups of macroalgae and invertebrates, and abundance and size of fishes. Spatial allocation of sampling is designed to measure year-to-year site-wide variability in community structure and the spatial scales at which such variation occurs. A site is defined as a fixed stretch of coastline, occupying approximately 500m. Originally, each site was divided into 2 halves (sides), each comprised of 12 transects startified across the four zones described above. Starting in 2007, many new sites were added for monitoring MPAs established by the MLPA along the coast of central California. These MLPA sites are equivalent of one "side" of the orignal PISCO sites (i.e. 12 transects).