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South Africa has taken an iterative approach to marine ecosystem mapping over 18 years that has provided a valuable foundation for ecosystem assessment, planning and decision-making, supporting improved ecosystem-based management and protection. Iterative progress has been made in overcoming challenges faced by developing countries, especially in the inaccessible marine realm. Our aim is to report on the approach to produce and improve a national marine ecosystem map to guide other countries facing similar challenges, and to illustrate the impact of even the simplest ecosystem map. South Africa has produced four map versions, from a rudimentary map of 34 biozones informed by bathymetry data, to the latest version comprising 163 ecosystem types informed by 83 environmental and biodiversity datasets that aligns with the IUCN Global Ecosystem Typology. Data were unlocked through academic and industry collaborations; multi-disciplinary, multi-realm and multi-generational networks of practitioners; and targeted research to address key gaps. To advance toward a more transparent, reproducible and data-driven approach, limitations, barriers and opportunities for improvement were identified. Challenges included limited human and data infrastructure capacity to collate, curate and assimilate many data sources, covering a variety of ecosystem components, methods and scales. Five key lessons that are of relevance for others working to advance ecosystem classification and mapping, were distilled. These include (1) the benefits of iterative improvement; (2) the value of fostering relationships among a co-ordinated network of practitioners including early-career researchers; (3) strategically prioritizing and leveraging resources to build and curate key foundational biodiversity datasets and understand drivers of biodiversity pattern; (4) the need for developing, transferring and applying capacity and tools that enhance data quality, analytical workflows and outputs; and (5) the application of new technology and emerging statistical tools to improve the classification and prediction of biodiversity pattern. South Africa’s map of marine ecosystem types has been successfully applied in spatial biodiversity assessment, prioritization to support protected area expansion and marine spatial planning. These successes demonstrate the value of a co-ordinated network of practitioners who continually build an evidence base and iteratively improve ecosystem mapping while simultaneously growing ecological knowledge and informing changing priorities and policy.

Commercial fishing in False Bay, South Africa, began in the 1600s. Today chondrichthyans are regularly taken in fisheries throughout the bay. Using a combination of catch, survey and life history data, the occurrence and long-term changes in populations of chondrichthyans in False Bay are described. Analyses of time series data from five fishing methods between 1897 and 2011 provided trends in relative abundance. Of the 37 species found in False Bay, 25 showed no significant trends for any fishing method. Of the 12 species and two genera with catch trends, four showed a common trend across methods, two increasing (Mustelus mustelus and Carcharhinus brachyurus) and two decreasing (Galeorhinus galeus and Raja spp.), while another two species (Triakis megalopterus and Isurus oxyrinchus) showed highly significant declines in one method only. A productivity index was used in conjunction with information on species distribution, catch frequency and trends in abundance to assess the vulnerability of False Bay chondrichthyans. Among the various habitats and depth strata, the surf-zone has been most impacted by exploitation, whereas the conservation of deep-water, soft-sediment species has benefited from the ban on trawling in False Bay implemented in 1928. Continued monitoring using catch data from beach-seine, recreational shore-angling and the commercial linefishery is recommended, along with improved species identification.Key words: chondrichthyans, elasmobranchs, exploitation, vulnerability, population trends, conservation.