South African Environmental Observation Network Offshore Demersal Invertebrate Monitoring Part 1

Latest version published by South African National Biodiversity Institute on Mar 26, 2024 South African National Biodiversity Institute
Publication date:
26 March 2024
CC-BY 4.0

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9793 Benthic marine invertebrate records sampled using a research demersal trawl net off the west and south coasts of South Africa during the years 2011 to 2022.

Data Records

The data in this occurrence resource has been published as a Darwin Core Archive (DwC-A), which is a standardized format for sharing biodiversity data as a set of one or more data tables. The core data table contains 9,793 records.

This IPT archives the data and thus serves as the data repository. The data and resource metadata are available for download in the downloads section. The versions table lists other versions of the resource that have been made publicly available and allows tracking changes made to the resource over time.


The table below shows only published versions of the resource that are publicly accessible.

How to cite

Researchers should cite this work as follows:

Atkinson LJ SAEON Offshore invertebrate research trawl programme.


Researchers should respect the following rights statement:

The publisher and rights holder of this work is South African National Biodiversity Institute. This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License.

GBIF Registration

This resource has been registered with GBIF, and assigned the following GBIF UUID: ab1d732a-2b19-4faa-b927-b2e4eccaeaaf.  South African National Biodiversity Institute publishes this resource, and is itself registered in GBIF as a data publisher endorsed by South African Biodiversity Information Facility.


Porifera; Cnidaria; Annelida; Arthropoda; Bryozoa; Branchiopoda; Mollusca; Echinodermata; Chordata; Hemichordata. Demersal; offshore marine epifauna; Invertebrates; research Trawl.; Observation


Dr Lara Atkinson
  • Metadata Provider
  • Originator
  • Point Of Contact
Offshore Marine Scientist
South African Environmental Observation Network
8001 Cape Town
Western Cape

Geographic Coverage

West and South coasts of South Africa, extending from the border with Namibia at the Orange River Mouth to Port Alfred

Bounding Coordinates South West [-36.75, 14.6], North East [-28.75, 26.9]

Taxonomic Coverage

All marine invertebrates that are retained in the research trawl net from each trawl deployed are identified and recorded. These surveys take place in collaboration with the annual demersal research surveys conducted by the Fisheries Department, currently under the Department of Forestry, Fisheries and Environment (DFFE).

Genus Psilaster

Total of 316 species belonging to 10 marine Phyla

Genus Haliporoides

Temporal Coverage

Start Date / End Date 2011-01-05 / 2022-02-08

Sampling Methods

Samples were collected using a research demersal trawl net towed for 30 minutes per trawl, unless hard ground was encountered or net was damaged in which case shorter tow durations are noted. Sampling unit is nautical miles squared.

Study Extent Demersal research trawl gear are used to collect invertebrates as bycatch during fish surveys. The trawl gear used is German Otter trawl with otter trawl boards and a footrope rope-wrapped chain. The mesh size of the codend liner was 40 mm stretched mesh. See Atkinson et al 2011 doi: 10.2989/1814232X.2011.572378 and Axelsen and Johnsen 2015 doi:10.1111/fog.12079
Quality Control Data were validated by engaging with experts where necessary and using various field guides. Coordinates of the start position of the trawl are provided and due to the depths at which the trawls operate and the uncertainty of where the vessel is in relation to the trawl net on the seafloor, no further useful co-ordinate uncertainty can be provided.

Method step description:

  1. N/A

Additional Metadata

Acknowledgement required by Egagasini Node, South African Environmental Observation Network.