Date (Creation)

2026-01-15

Date (Revision)

2026-01-15

Date (Publication)

2026-01-15

Date (released)

2026-01-15

Edition

1.0

Unique resource identifier

https://doi.org/10.5285/93a1239d-e0b6-4ed4-889f-63126d0ffb80

Codespace

doi

Unique resource identifier

GB/NERC/BAS/PDC/02136

Codespace

https://data.bas.ac.uk/

Other citation details

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

Credit

No credit.

Status

Completed

Point of contact

Organisation name	Individual name	Electronic mail address	Role
British Antarctic Survey	Collins, Martin		Author
Government of South Georgia & the South Sandwich Islands	Belchier, Mark		Author
Government of South Georgia & the South Sandwich Islands	Gregory, Sue		Author
Bangor University	Hollyman, Philip		Author
University of East Anglia	Everson, Inigo		Author
British Antarctic Survey	Jones, Timothy		Author
NERC EDS UK Polar Data Centre		PDCServiceDesk@bas.ac.uk	Point of contact

Maintenance and update frequency

As needed

Maintenance note

Completed

Global Change Master Directory (GCMD) Science Keywords

• EARTH SCIENCE > Agriculture > Agricultural Aquatic Sciences > Fisheries
• EARTH SCIENCE > Biosphere > Ecological Dynamics > Biomass
• EARTH SCIENCE > Oceans > Marine Biology > Fish

Theme

• demersal fish

• diet composition

• fish biomass

• trawl survey

Place

• South Georgia, Scotia Sea South Atlantic Ocean

• Shag Rocks, South Georgia, Scotia Sea South Atlantic Ocean

GEMET - INSPIRE themes, version 1.0

• Agricultural and aquaculture facilities
• Habitats and biotopes
• Oceanographic geographical features

Access constraints

Other restrictions

Other constraints

no limitations to public access

Access constraints

Other restrictions

Other constraints

no limitations

Use constraints

License

Other constraints

Open Government Licence v3.0

Use constraints

Other restrictions

Other constraints

This data is governed by the NERC Data Policy: https://www.ukri.org/who-we-are/nerc/our-policies-and-standards/nerc-data-policy/

Use constraints

Other restrictions

Other constraints

and supplied under Open Government Licence v.3 ().

Use constraints

Other restrictions

Other constraints

None

Unique resource identifier

url

Codespace

url

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Unique resource identifier

doi

Codespace

doi

Association Type

Cross reference

Spatial representation type

Text, table

Language

English

Character set

UTF8

Topic category

• Biota

Begin date

1986-11-29

End date

2023-02-10

Supplemental Information

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.

Title

European Petroleum Survey Group (EPSG) Geodetic Parameter Registry

Date (Publication)

2008-11-12

Cited responsible party

Organisation name	Individual name	Electronic mail address	Role
European Petroleum Survey Group		EPSGadministrator@iogp.org	Publisher

Unique resource identifier

urn:ogc:def:crs:EPSG::3031

Version

6.18.3

Hierarchy level

Dataset

Statement

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.

Metadata

File identifier

93a1239d-e0b6-4ed4-889f-63126d0ffb80 XML

Metadata language

English

Character set

UTF8

Hierarchy level

Dataset

Hierarchy level name

dataset

Date stamp

2026-01-15

Metadata standard name

ISO 19115 Geographic Information - Metadata

Metadata standard version

ISO 19115:2003(E)

Metadata author

Organisation name	Individual name	Electronic mail address	Role
NERC EDS UK Polar Data Centre		polardatacentre@bas.ac.uk	Point of contact