The2010Charting Progress 2(CP2)assessment(UKMMAS 2010)subdividedUK waters into eight regionsto assess how human use and other pressures(such as climate change) wereaffectingthe productivity of UK seas. Regional boundaries were developed in 2009, adapting 'regional seas' previously identified on the basis of physical and biological biogeography by the Review of Marine Nature Conservation (RMNC) 2004. The CP2 'Reporting Regions' have subsequently informed a variety of MPA designation, marine assessment and reporting purposesand continue to be used, for example in the selection of Highly Protected Marine Areas, indicators for the ecological status of the water environment, and the aggregation of marine biotope sensitivity information.

Key updatesto the CP2 Reporting Regions undertaken by JNCC in 2022:

• updating theoutermaritimeboundaries of CP2 regions to align with the UK Exclusive Economic Zone (EEZ)and UKContinental Shelf (UKCS)limits that came into force in 2013. EEZ and UKCSlimit data were obtained from the UKHO ADMIRALTY service(UK Hydrographic Office Maritime Limits and Boundaries | ADMIRALTY Marine Data Portal) in July 2022

• subdividingthe Scottish Continental Shelf (region 7) and the Atlantic North-West Approaches, Rockall Trough and Faroe Shetland Channel (region 8) by maritime limits (UKCS, EEZ and the ‘Special Area’ of shared jurisdiction with The Faroes, for ease of use according to different definitions of UK waters. Note that the biogeographic boundaries between regions remain unchanged.

• updatingthe Isle of Man Territorial Sea limit(to exclude Isle of Man waters from region 6), using UKHO ADMIRALTY data obtained in July 2022

• incorporating a more up-to-date and (in most places) improved resolution coastline for England, Scotland and Wales.A mean high water (springs) 'BoundaryLine' dataset (version date05-2022) was obtained from the Ordnance Survey https://osdatahub.os.uk/downloads/open/BoundaryLine*

• incorporating amore up-to-date and(in most places)improved resolution coastline for Northern Ireland.A mean high water 'NI outline' dataset (version 1.0, dated 23 June 2022) was obtained from the Ordnance Survey of Northern Ireland (OSNI) https://www.opendatani.gov.uk/@land-property/osni-open-data-largescale-boundaries-ni-outline1 ~

• minor edits to CP2 reporting region boundaries to ensure they joined to the updated coastlines

• topological corrections to CP2 reporting region boundaries, e.g. where minor gaps/slivers or overlaps occurred between regions.

* prior to use,the BoundaryLine coastline dataset was converted to feature class and dissolved into onecontinuousline feature, then reprojected from British National Grid into WGS1984 using the OSTN15_NTv2_OSGBtoETRS transformation.~ prior to use, the NI outline dataset was reprojected from TM65 Irish Grid into WGS 1984 using the TM65_WGS_1984_2 transformation.

Data limitationsand notes:

• the open data coastline datasetsareof medium spatial resolution but lack detail in some areas, e.g. sea lochs and islets in the Hebrides, Orkneys and Shetland, pladdies in Strangford Loch and islets around Northern Ireland. The OS BoundaryLine dataset for England, Wales and Scotland is not as detailed as the high resolution (charged for) OS MasterMap dataset.

• part of the Scottish Continental Shelf (region 7) boundary was originally drawn to align with the UK Territorial Waters limit around Orkney and Fair Isle. This section of boundary has not been updated and therefore remains consistent with the biogeographic boundary created in 2009.

• in the absence of formally agreed maritime limits,linework fromthe original 2009 CP2 Reporting Regions datasethas been retained to represent the boundary between the Northern Ireland Inshore Region and Republic of Ireland inshore waters

• note that the use of the CP2 Reporting Regions (or other biogeographic regions and assessment units) by JNCC, the SNCBs and other ALBs will vary by purpose. Variations of the CP2 Reporting Regions may be used for assessment purposes.