93a1239d-e0b6-4ed4-889f-63126d0ffb80 eng utf8 dataset dataset NERC EDS UK Polar Data Centre +44 (0)1223 221400 British Antarctic Survey, High Cross, Madingley Road Cambridge Cambridgeshire CB3 0ET United Kingdom polardatacentre@bas.ac.uk https://www.bas.ac.uk/team/business-teams/information-services/uk-polar-data-centre/ information pointOfContact 2026-01-15 ISO 19115 Geographic Information - Metadata ISO 19115:2003(E) European Petroleum Survey Group (EPSG) Geodetic Parameter Registry 2008-11-12 publication European Petroleum Survey Group EPSGadministrator@iogp.org https://www.epsg-registry.org/ EPSG Geodetic Parameter Dataset The EPSG Geodetic Parameter Dataset is a structured dataset of Coordinate Reference Systems and Coordinate Transformations, accessible through this online registry. information publisher urn:ogc:def:crs:EPSG::3031 6.18.3 Mackerel icefish (Champsocephalus gunnari) catches, biomass and diet composition from the South Georgia (southwest Atlantic) groundfish survey, 1986-2023 2026-01-15 creation 2026-01-15 revision 2026-01-15 publication 2026-01-15 released 1.0 https://doi.org/10.5285/93a1239d-e0b6-4ed4-889f-63126d0ffb80 doi GB/NERC/BAS/PDC/02136 https://data.bas.ac.uk/ Please cite this item as: Collins, M., Belchier, M., Gregory, S., Hollyman, P., Everson, I., & Jones, T. (2026). Mackerel icefish (Champsocephalus gunnari) catches, biomass and diet composition from the South Georgia (southwest Atlantic) groundfish survey, 1986-2023 (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/93a1239d-e0b6-4ed4-889f-63126d0ffb80 This dataset consists of biomass data and diet composition of mackerel icefish (Champsocephalus gunnari) from the South Georgia groundfish survey, collected during scientific trawl surveys from 1986 to 2023. These data were primarily collected to produce estimates of mackerel icefish biomass to inform management of the icefish fishery, and to further our understanding of icefish ecology, distribution, and diet. Data were primarily collected by Martin A. Collins, Mark Belchier, Inigo Everson, Jude Brown, Phil Hollyman, Simeon Hill, Tom Marlow, Caradoc Jones, Rebecca Mitchell & Sue Gregory. Since 1990, the South Georgia groundfish surveys were funded by the Government of South Georgia and the South Sandwich Islands. Earlier surveys were funded by the US and Polish governments. No credit. completed Collins, Martin British Antarctic Survey Researcher author Belchier, Mark Government of South Georgia & the South Sandwich Islands Researcher author Gregory, Sue Government of South Georgia & the South Sandwich Islands Researcher author Hollyman, Philip Bangor University Researcher author Everson, Inigo University of East Anglia Researcher author Jones, Timothy British Antarctic Survey Researcher author NERC EDS UK Polar Data Centre +44 (0)1223 221400 British Antarctic Survey, High Cross, Madingley Road Cambridge Cambridgeshire CB3 0ET United Kingdom PDCServiceDesk@bas.ac.uk https://www.bas.ac.uk/team/business-teams/information-services/uk-polar-data-centre/ information pointOfContact asNeeded completed EARTH SCIENCE > Agriculture > Agricultural Aquatic Sciences > Fisheries EARTH SCIENCE > Biosphere > Ecological Dynamics > Biomass EARTH SCIENCE > Oceans > Marine Biology > Fish theme Global Change Master Directory (GCMD) Science Keywords 2026-01-27 publication 23 Global Change Data Center, Science and Exploration Directorate, Goddard Space Flight Center (GSFC) National Aeronautics and Space Administration (NASA) Greenbelt MD United States of America https://earthdata.nasa.gov/about/gcmd/global-change-master-directory-gcmd-keywords Global Change Master Directory (GCMD) Keywords The information provided on this page seeks to define how the GCMD Keywords are structured, used and accessed. It also provides information on how users can participate in the further development of the keywords. information publisher demersal fish diet composition fish biomass trawl survey theme South Georgia, Scotia Sea South Atlantic Ocean Shag Rocks, South Georgia, Scotia Sea South Atlantic Ocean place Agricultural and aquaculture facilities Habitats and biotopes Oceanographic geographical features theme GEMET - INSPIRE themes, version 1.0 2021-01-06 revision otherRestrictions no limitations to public access otherRestrictions no limitations license Open Government Licence v3.0 otherRestrictions This data is governed by the NERC Data Policy: https://www.ukri.org/who-we-are/nerc/our-policies-and-standards/nerc-data-policy/ otherRestrictions and supplied under Open Government Licence v.3 (). otherRestrictions None url url crossReference doi doi crossReference doi doi crossReference textTable eng utf8 biota -42.982 -34.275 -55.499 -53.277 1986-11-29 2023-02-10 It is recommended that careful attention be paid to the contents of any data, and that the author be contacted with any questions regarding appropriate use. If you find any errors or omissions, please report them to polardatacentre@bas.ac.uk. NERC EDS UK Polar Data Centre +44 (0)1223 221400 British Antarctic Survey, High Cross, Madingley Road Cambridge Cambridgeshire CB3 0ET United Kingdom PDCServiceDesk@bas.ac.uk https://www.bas.ac.uk/team/business-teams/information-services/uk-polar-data-centre/ information distributor bytes 1 http://ramadda.data.bas.ac.uk/repository/entry/show?entryid=93a1239d-e0b6-4ed4-889f-63126d0ffb80 WWW:LINK-1.0-http--link Get Data Download data download dataset Methodology: Trawl surveys Data on the abundance and distribution of Champsocephalus gunnari were collected during 28 demersal trawl surveys conducted primarily during the austral summer (Nov-Feb) at South Georgia and Shag Rocks, between 1987 and 2023. The survey design has remained constant throughout the time series despite changes in survey vessel. From the 1991 survey onwards, gear was standardized (commercial sized otter trawl FP-120, wingspread 18-20 m, headline height 3-6 m, cod end mesh 40 mm). Before this, broadly similar gear was used on each of the early surveys (Belchier et al., 2015). The area was surveyed using a random-stratified design, subdividing into five sectors: Shag Rocks plus the four quadrants of the South Georgia shelf; northwest, northeast, southwest, and southeast. Trawls were conducted for 30 minutes at a speed of 3-4 knots, and at two depth zones: 100-200 m and 201-350 m. The trawl dataset also contains data from winter surveys, performed using the standard survey design but in April/May (2008 and 2021) or September (1997 and 2007), and dedicated deepwater surveys (350-1000 m) During each survey, the total catch of C. gunnari in each trawl was recorded along with information on trawl location, time, depth, and trawl characteristics (trawl duration, distance trawled, horizontal and vertical net opening). Diet data Since 2004, stomach contents of mackerel icefish have been collected on a routine basis using a standard methodology developed by Main et al. (2009). Samples of C. gunnari (typically less than or equal to 30 per trawl) were collected from all trawls in which the species was caught. Sampled fish were measured and weighed, stomachs were removed and immediately frozen at -20 degrees centigrade, for later processing and macroscopic identification of stomach contents. Stomach contents were thawed and sorted in the laboratory at King Edward Point, South Georgia. Once the stomach contents were sorted, individual prey items were counted and weighed to the nearest 0.01g. Diet composition per fish sampled were aggregated at two levels. Gross survey averages of diet composition were produced by first assigning prey items into one of 11 broad taxonomic groups (Euphausia superba, Other Euphausia spp., Thysanoessa sp., Themisto gaudichaudii, Antarctomysis sp., Other/unknown crustacean, Nototheniidae, Channichthyidae, Myctophidae, Other/unknown fish, Other/unknown), then finding the summed mass for each group across all fish sampled from the Shag Rocks and South Georgia shelves per survey. These are then presented as proportional composition by dividing by the net total across groups per survey and shelf area. The proportion of krill in stomach contents per trawl was calculated by taking the summed mass of krill and dividing by the summed mass across all prey taxa, where the sums are performed across fish stomach contents from each trawl with diet information. Data collection: All data processing and cleaning were performed in R version 4.3.3 (R Core Team 2024). Data quality: Raw trawl data were cleaned to remove trawls hauled early due to unsuitable ground, and those that were deemed unrepresentative due to gear failure. asNeeded completed