GIS data of urchin barren mapping in Northeastern New Zealand

On shallow rocky reefs in northeastern Aotearoa, New Zealand, urchin barrens are recognised as indicators of the ecosystem effects of overfishing reef predators. Yet, information on their extent and variability is lacking. We use aerial imagery to map the urchin barrens and kelp forests on reefs (<30 m depth) across seven locations, including within two long-established marine reserves and a marine protected area that allows recreational fishing. Urchin barrens were present in all locations and were restricted to reefs <10-16 m deep. This archive contains ArcGIS shapefiles and layer files for all of the maps used in this study. The study area extends from Cape Reinga in the far north of the North Island to Tawharanui in the Hauraki Gulf near Auckland. Regional scale base maps of the prominent marine habitats were included along with the seven fine-scale maps where the kelp forests and urchin barrens were mapped.

Methods
The GIS shapefiles produced in this study were hand-drawn over layers of low-level aerial photography taken in specific conditions, which maximised the visible depth observable to create polygons to depict the habitat boundaries of the shallow reef. Of particular interest was the mapping of urchin barrens. Ground truthing surveys creating point data and underwater imagery were also brought into the GIS project to assist in drawing the reef habitat polygons. Arc layer files contain a common symbology across the seven study maps to aid the interpretation of the mapping. Further information on the methodology used in the mapping can be found in two published papers and four technical reports corresponding to the maps. The Readme file details where technical reports and published reports can be downloaded from the internet.