39078590-3ee7-4e67-9d6f-f8072be3b6c6 English HELCOM Secretariat data@helcom.fi 2021-09-09T11:58:39 EPSG:3035 Herring abundance (HOLAS 2) 2018-06-01 https://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/39078590-3ee7-4e67-9d6f-f8072be3b6c6 The map of herring relative abundance is mainly based on Baltic International acoustic surveys (BIAS), years 2011-2016 (ICES WGBIFS reports), reported as millions of herring / ICES rectangle. Also herring landings data were used to complement the data. For ICES rectangles surveyed by BIAS, values shown are the mean values per ICES rectangle based on BIAS data, average for 2011-2016. For ICES rectangles not surveyed by BIAS, values are calculated as: MAX-value x Weighting factor. The weighting factor is specific to each ICES rectangle, calculated as the ratio between the commercial landings in that rectangle and the commercial landings in the ICES rectangle with highest landings (based on averages for 2011-2016). MAX-value = millions of herring according to BIAS in the ICES rectangle with highest landings. ICES rectangles outside the BIAS survey area with no reported herring landings were given the value 0. The relative abundance values in each ICES rectangle were divided by the area of the rectangle to obtain values per 1km2. If the values in small coastal ICES rectangles (outside BIAS area) became unrealistically large due to high herring landings, the value of the neighboring rectangle was given. The final layer was converted to 1 km x 1km grid cells. Values were first log transformed and normalized. HELCOM Secretariat data@helcom.fi Species distribution GEMET - INSPIRE themes, version 1.0 2008-06-01 geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme marine ecology fish GEMET 2018-08-16 geonetwork.thesaurus.external.theme.gemet-en MADS HOLAS2 ecosystem component Biodiversity Use constraints: Data can be used freely given that the source is cited. Access constraints: No limitations on public access. English environment biota 7.530495 34.131647 52.277123 66.475422 2011-01-01 2016-12-31 TIFF https://maps.helcom.fi/website/MADS/download/?id=39078590-3ee7-4e67-9d6f-f8072be3b6c6 WWW:LINK-1.0-http--link Download dataset Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 Data source: Baltic International acoustic survey (BIAS) data from 2011-2016, from ICES WGBIFS reports - Does not cover the whole Baltic Sea. - Reported as millions of herring / ICES statistical rectangle - all ages included Landings data from EU Joint research Centre (https://datacollection.jrc.ec.europa.eu/dd/effort/maps) from years 2011-2016 (= fisheries data). - Data reported as tonnes / ICES statistical rectangle Data quality: The quality of fisheries independent BIAS data can be considered good, as the surveys are specifically designed for estimating fish abundance in the Baltic Sea. Outside BIAS area, the quality of the data decreases, as it is based on an estimate based on weighting derived from landings data. Attribute information: Ecosystem abundance value from 0 to 1 (millions of herring / km2, log-transformed and normalized) Spatial resolution: Original data in ICES rectangles, here 1 km x 1 km grid. Time period and temporal resolution: BIAS data 2011-2016, landings data 2011-2016.