Sampling event

VIS - Estuarine monitoring in Flanders, Belgium (post 2013)

Latest version published by Research Institute for Nature and Forest (INBO) on 5 December 2023 Research Institute for Nature and Forest (INBO)
Publication date:
5 December 2023
CC0 1.0

Download the latest version of this resource data as a Darwin Core Archive (DwC-A) or the resource metadata as EML or RTF:

Data as a DwC-A file download 883 records in English (567 KB) - Update frequency: annually
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Metadata as an RTF file download in English (15 KB)


VIS - Estuarine monitoring in Flanders, Belgium (post 2013) is a sampling event dataset published by the Research Institute for Nature and Forest (INBO). The dataset contains close to 32,000 fish occurrences sampled between 2013 and 2016 from 33 locations in the estuary of the river Yser and the part of the river Scheldt under tidal influence ("Zeeschelde"). The dataset includes over 60 fish species, as well as a number of non-target crustacean species. The data are retrieved from the Fish Information System (VIS), a database set up to monitor the status of fishes and their habitats in Flanders and are collected in support of the Water Framework Directive, the Habitat Directive, certain red lists, and biodiversity research. The VIS database is described in Brosens et al. 2015 ( Additional information, such as measurements, absence information and abiotic data are available upon request. Issues with the dataset can be reported at

Length and weight measurement data of the individual fishes, absence information, occurrence data since 2015, as well as abiotic data of the sampling points (pH, temperature, etc.) are not included in the Darwin Core Archive and are available upon request.

We released the data to the public domain under a Creative Commons Zero waiver ( We would appreciate however, if you read and follow these norms for data use ( and provide a link to the original dataset ( whenever possible. If you use these data for a scientific paper, please cite the dataset following the applicable citation norms and/or consider us for co-authorship. We are always interested to know how you have used or visualized the data, or to provide more information, so please contact us via the contact information provided in the metadata, or

Data Records

The data in this sampling event 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 883 records.

1 extension data tables also exist. An extension record supplies extra information about a core record. The number of records in each extension data table is illustrated below.

Event (core)

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:

Breine J, Brosens D, Desmet P (2023). VIS - Estuarine monitoring in Flanders, Belgium (post 2013). Version 1.13. Research Institute for Nature and Forest (INBO). Samplingevent dataset.


Researchers should respect the following rights statement:

The publisher and rights holder of this work is Research Institute for Nature and Forest (INBO). To the extent possible under law, the publisher has waived all rights to these data and has dedicated them to the Public Domain (CC0 1.0). Users may copy, modify, distribute and use the work, including for commercial purposes, without restriction.

GBIF Registration

This resource has been registered with GBIF, and assigned the following GBIF UUID: 702973cf-6935-45bf-ba31-cecee3571cf9.  Research Institute for Nature and Forest (INBO) publishes this resource, and is itself registered in GBIF as a data publisher endorsed by Belgian Biodiversity Platform.


Samplingevent; occurrence; ecosystem functioning; fish-based index of biotic integrity; fish distribution; brackish water; estuary; open data; River Scheldt; River Yser; Zeeschelde; Samplingevent


Jan Breine
  • Originator
  • Point Of Contact
Research Institute for Nature and Forest (INBO)
Flemish Brabant
Dimitri Brosens
  • Metadata Provider
  • Originator
Data liaison officer
Research Institute for Nature and Forest (INBO)
Kliniekstraat 25
1070 Brussels
Brussels Capital Region
Peter Desmet
  • Metadata Provider
Data lab coordinator
Research Institute for Nature and Forest (INBO)
Kliniekstraat 25
1070 Brussels
Brussels Capital Region

Geographic Coverage

Estuary of the river Yser and the part of the river Scheldt under tidal influence ("Zeeschelde") in Flanders, Belgium.

Bounding Coordinates South West [50.68, 2.54], North East [51.51, 4.59]

Taxonomic Coverage

The dataset contains more than 60 fish species found in the estuaries of the rivers Yser and Scheldt, as well as 10 non-target crustacean and 2 gastropod species. The class of Actinopterygii is most represented (55 species). All the crustaceans in this dataset are from the order of the Decapoda.

Kingdom Animalia
Class Actinopterygii, Malacostraca, Gastropoda

Temporal Coverage

Start Date / End Date 2013-01-01 / 2023-01-01

Sampling Methods

Standardized sampling methods were used as described in Belpaire et al. (2000) and Van Thuyne & Breine (2010) and are specified in the dataset as dwc:samplingProtocol. Per water body, the same method was used for each sampling event. The default method is paired fyke netting, which has been intercalibrated by the North East Atlantic Calibration Group, but additional techniques such as anchor netting, seine netting, pound netting, electric fishing, and eel fyke netting were used as well (Breine et al. 2011). All fishes were identified to species level, counted and their length and weight was measured. Fyke nets are relatively unselective fishing gear catching demersal and pelagic species (Hamerlynck and Hostens 1994) and also they are easy to install in a great variety of habitat types. As few studies compare fyke catches with other gear (e.g. Hinz 1989, Thiel and Potter 2001), we compared presence/absence data obtained with fyke nets with presence/absence data of fish impinged at cooling-water filter screens of the nuclear power plant of Doel situated in the study area. The data was collected in the same period between 1995 and 1998. During this period we collected the same species with both survey methods but the species richness per day per fyke net was generally higher than that obtained on the filter screens (Breine et al. 2007). In addition preliminary results from a gear intercalibration exercise in different estuaries in Ireland (Whyte et al. 2007) indicated that for species diversity, the results of fyke net catches are comparable to those obtained with other gear (beach seine, beam trawl, otter trawl).

Study Extent Over 2,000 locations in estuaries, inland rivers, streams, canals, and enclosed waters in Flanders, Belgium have been sampled, from March to November, since 1992. In 2001, these locations were consolidated in a monitoring network (“VISmeetnet”) of 900 sampling points. Four locations in the Yser estuary and 43 locations in the Zeeschelde were sampled since 1995. While the Yser estuary only covers a small geographical area, the Scheldt estuary is with 33,000 hectares one of the largest estuaries in Europe. It is also one of the few remaining European estuaries that includes the entire gradient from fresh to saltwater tidal areas (Van den Bergh et al. 2009). The 43 sampling locations in the Scheldt estuary are mainly located in the Zeeschelde, but also in the Rivers Durme, Rupel, Dijle, Zenne and Nete. The geographic coordinates in the dataset are those of the defined sampling locations (dwc:locationID). However, as these coordinates are not always exact the actual coordinates of the catch, which may be located further up- or downriver, the coordinate uncertainty (dwc:coordinateUncertaintyInMeters) has been set to 250 meter.
Quality Control Strict field protocols where used. The Manual for Application of the European Fish Index (EFI) (Fame consortium 2004) served as a guideline for electrofishing and was used in support of the EU water framework directive.

Method step description:

  1. Water type: Estuaries Method: fyke fishing, anchor netting, pound netting, electric fishing Effort: Fykes: 2 paired nets for two successive days per site. Winged fyke: one per site for two successive days. Anchor netting: per site 4 surveys of one hour (two for each tide). Electric fishing: only in flood control areas (250 m shore transects/ha).

Bibliographic Citations

  1. Brosens D, Breine J, Van Thuyne G, Belpaire C, Desmet P, Verreycken H (2015) VIS – A database on the distribution of fishes in inland and estuarine waters in Flanders, Belgium. ZooKeys 475: 119-145.

Additional Metadata

Purpose The Fish Information System or VIS ( is a database created by the Research Institute for Nature and Forest (INBO) which is used to monitor the status of fishes and their habitats in Flanders, Belgium and to calculate the biotic integrity (Karr 1981, Belpaire et al. 2000, Breine et al. 2004, 2007, 2010) of fish assemblages. It contains data regarding occurrences, individual morphometrics, stocks, pollutants, indices, and non-native fish species. Sampling has been going on since 1992, the database model was designed in 1994 (Verbiest et al. 1994), the first database developed in 1996 (Verbiest et al. 1996), and the consolidated database set up in 2001. VIS is used for supporting NATURA 2000, an ecological network of protected areas in Europe and to calculate the EQR (Ecological Quality Ratio) in the framework of the EU Water Directive (Directive 2000/60/EC). Further, the database provides updated information for Flemish Red Lists of fishes and lampreys (Verreycken et al. 2014) and on the distribution status of non-native and invasive fish species. The data are also crucial in fish stock management and for reporting on the status of the European eel stock as required by the Eel Regulation (Council Regulation (EC) N° 1100/2007). This dataset is a standardized extraction of all estuarine species occurrences from VIS since 2013.
Alternative Identifiers 702973cf-6935-45bf-ba31-cecee3571cf9