Input of impulsive anthropogenic sound includes impulsive events from 2011-2016 • Seismic surveys (HELCOM-OSPAR Registry; national data call submissions as lines in the folder of data) • Explosions (HELCOM-OSPAR Registry) • Pile driving (HELCOM-OSPAR Registry) • Airguns (HELCOM-OSPAR Registry) For the different event types, numeric intensity value was used to represent the pressure as categorized in HELCOM-OSPAR Impulsive noise registry. All nationally reported seismic surveys were given intensity values “Very low” (0.25) - Very low (0.25) - Low (0.5) - Medium (0.75) - High (1) The impact distance has not been taken into account due to the different nature of separate datasets used for the pressure layer. We acknowledge that e.g. pile driving and airguns may impact up to 20 km from the source event. The spread of the sound wave depends on the sound frequency, water salinity, temperature and density.

Pressure layer combines all human activities that cause changes to hydrological conditions. The human activities were presented as point data which were given spatial extents (given below). The pressure value was given as the proportion of the grid cell under the pressure. The following human activities were combined into the changes to hydrological conditions layer; - Hydropower dams (a 1km2 grid cell in the river estuary was selected) - Water course modification (1 km) - Wind turbines (operational, 0.3 km, linear decline) - Oil platforms (0.5 km, linear decline) The human activity datasets were first processed separately covering the whole Baltic Sea and then summed together and overlapping areas were dissolved to remove double counting. Attenuation gradients are assigned to each layer as described above. Area effected decreases when distance from avtivity increases. Layer was normalized.

This layer is based on data from the BIAS project representing ambient underwater noise, modelled into a 0.5 km x 0.5 km grid, and representing sound pressure levels at 1/3 octave bands of 125 Hz exceeded at least 5% of the time. Measured and modelled acoustic data is provided as Sound Pressure Level (SPL). The time period for the data is annual values for year 2014. The selected depth interval is 0 m – bottom to represent the ambient underwater noise in the whole water column. The data were normalized setting level 0 at 92 db re 1µPa and level 1 at 127 db re 1µPa.

This dataset is built from following Human activities datasets: • http://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/81c917ea-492d-48e2-9f00-e1bb7fe3e4fc • http://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/4fcd51dd-b8be-4e83-8cad-37c566782e8f The game hunting of seabirds data (see separate metadata): The total number of hunted seabirds were averaged over 2011-2015 (number of hunted seabirds / year). The area of the reporting unit was used to calculate the number of hunted seabirds / km2 and the data was converted to 1km x 1km grid. The predator control of seabirds data (see separate metadata): The total number of hunted cormorants were averaged over 2011-2015 (number of hunted cormorants / year). The area of the reporting unit was used to calculate the number of hunted cormorants / km2 and the data was converted to 1km x 1km grid. The two datasets were first separately log transformed and then summed, to get the total value for each grid cell. Zero values were given to all grid cells with no reported seabird hunting activity. The layer was normalized.

Data shows the extent of land claim (permanent or temporary establishments of the sea) and the type of the construction. The data was made available by HELCOM Contracting Parties in response to data request. The data was received from Denmark, Finland, Sweden and Poland. The activity was declared as not relevant in Germany, Estonia, Latvia and Lithuanian. From Russia no data was reported. Attribute specification and units: Country: Country Type: Type of construction (land claim) Type_spec: More specified information about the type of land claim Year: Year of construction Estimated: Estimated year of construction from the identification information (environmental permit) given by the country in question Length: Length of the land reclamation (m) Area: Area (km2) of the land claim X_lon: Original Longitude coordinate point (for the data that has been transformed from points into lines) Y_Lat: Original latitude coordinate point (for the data that has been transformed from points into lines)

The dataset contains total landings of sprat for years 2011-2016 reported per ICES statistical rectangles (tonnes / ICES rectangle) under EU Joint Research Centre’s data collection framework for fisheries data. Russian data extracted from ICES annual reports.

Physical loss pressure layer combines all human activities that cause physical loss of seabed. The pressure is given as area lost in each cell (km2). For the polygon datasets the area was assumed to be the lost area. For line and point datasets spatial extents were calculated with buffers (below in brackets). If no buffer extent is indicated, the data was reported as polygon. The human activities used for the physical loss pressure: - Bridges (2 m) - Cables (operational; 1,5 m) - Coastal defence and flood protection (area of polygon, 50 m for lines) - Dredging (capital dredging, Area of polygon or a 25/50 m buffer for <5000 m3 / >5000m3 points) - Extraction of sand and gravel - Finfish mariculture (150 m) - Harbours (polygon with 200 m buffer) - Land claim (area of polygon, 30m buffer for lines) - Marinas and leisure harbours (200 m) - Oil platforms (25 m) - Oil terminals and refineries (200 m) - Pipelines (operational; 15 m) - Shellfish mariculture (area of polygon, 150 m points) - Watercourse modification (50 m) - Wind turbines (operational; 30m point location of turbine) The datasets were first processed separately covering the whole Baltic Sea and then merged into one uniform data layer and minimizing the effect of overlapping areas. Polygon areas were clipped with coastline to remove buffered areas that reached to land.

Data set represents dredging activities around the Baltic Sea. The dataset contains information about the dredging activity and for some the type (capital, maintenance) and the year of activity as reported by HELCOM Contracting Parties in response to data request. The dredging data is missing from Denmark.

The dataset contains sand and gravel extraction activity during 2011–2015. The dataset is based on data submission by HELCOM Contacting Parties in response to data request. The dataset is quality assured and contains data from all the Baltic Sea countries. Common extraction sites with information on volume of extraction was included in the dataset. The other extraction sites (building sites, exclusive sites) had only summed data for all the sites, as volumes of extraction in specific sites was classified as confidential information. For these sites the volumes was calculated from reported sum of "other extraction areas". The amount was equally divided between corresponding extraction areas. For some common extraction sites a shared amount was reported.

The extraction of herring data set is based on: 1. http://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/a3b67a55-7c1e-469e-b692-58c4e7b79279 for years 2011-2016 reported per ICES statistical rectangles (tonnes / ICES rectangle). Landing values were redistributed within each ICES rectangle by the c-square fishing effort data provided by ICES (all gears, 2011-2013). Tonnes / km² was calculated and the results were converted to 1 km x 1 km grid cells. The layer was log-transformed and normalised to produce the final pressure layer on extraction of herring. Please see "lineage" section below for further details on attributes, data source, data processing, etc.