Trekvis - Migratory fishes in the river Scheldt
Citation
Stevens M (2022). Trekvis - Migratory fishes in the river Scheldt. Version 70.8. Research Institute for Nature and Forest (INBO). Occurrence dataset https://doi.org/10.15468/j9tj7x accessed via GBIF.org on 2024-12-11.Description
In the context of the "Trekvis" migratory fish project fykes are placed at a few locations in the river Scheldt and among the most important fish migration bottlenecks in the basin of the Scheldt. Every month, traps placed 24 hours later retrieved. All fish are determinatie, measured and weighed.
To allow anyone to use this dataset, we have released the data to the public domain under a Creative Commons Zero waiver (http://creativecommons.org/publicdomain/zero/1.0/). We would appreciate however, if you read and follow these norms for data use (http://www.inbo.be/en/norms-for-data-use) and provide a link to the original dataset (https://doi.org/10.15468/j9tj7x) 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, opendata@inbo.be or https://twitter.com/LifeWatchINBO.
Sampling Description
Study Extent
The Long-Term Vision (LTV) for the Schelde estuary is a Dutch-Flemish managerial plan. Its ultimate goal is to reconcile the apparent conflicting multiple functions of the estuary in sustainable integrated management. The LTV sets quality targets for the estuary in the year 2030 and the management measures to achieve them. These goals and management are integrated from three central perspectives: accessibility, flood management and ecology. In this framework, in the Memorandum of Vlissingen (2002) agreements were made about a long-term monitoring and research program to support the cross-border cooperation of policy and management in the Schelde-estuary. In addition to the three main perspectives, the decree also pays attention to themes like fisheries and recreation. The present project 'Trekvis' is part of the theme 'fish and fisheries' and was contracted by the Maritime Access Division of the Department of Public Works of the Flemish government to the Research. Institute for Nature and Forest (INBO). This study aims to investigate the present status of diadromous fishes in the Schelde basin and to formulate measures for an integrated estuarine ecosystem management. Hereto, the causes for the local decline and extinction of the diadromous species were discussed and their present distribution in the Schelde basin was investigated in a field study. Based on this, a proposal for the monitoring of diadromous fishes and management actions are presented in order to come to a sustainable recovery of the diadromous fish populations in the Schelde basin. ## Distribution and status of diadromous fishes in the Schelde Catadromous species like European eel, flounder and thinlip mullet are quite abundant in the estuary. These species spawn at sea and use the estuary as a nursery or growing-up habitat. Their density is highest in summer. Thinlip mullets were caught in the freshwater zone for the first time and juvenile flounder arrives into the Zeeschelde from May on. The upstream sections of the river, above the tidal zone, are probably less important for these species. Eels, on the other hand, also colonize the upstream rivers, but their migration depends on the population density in the estuary. The status of the eel stock depends on the recruitment of glass eels. However, the recruitment of glass eels decreased dramatically during the last three decades and the eel stock is now in a critical state and well below safe biological limits. The occurrence of anadromous species in the estuary is related mainly to their pawning migration during winter and spring. In this period, mature smelts, river lampreys and threespined sticklebacks migrate upstream to reproduce in the freshwater zone. River lamprey was caught under the weir of Merelbeke as well as under the weir of Asper, indicating that their spawning grounds are further upstream. Both weirs/sluices are important migration barriers for this species. There are strong indications that the life cycle of river lamprey is complete in the Schelde, but the spawning sites and the larval habitats are unknown. Smelt was not caught upstream of the weir of Merelbeke. According to the literature, this species reproduces near the limit of tidal influence. Hence it is doubtful whether the riverine zone upstream of the barrier in Merelbeke is essential for the recovery of smelt in the Schelde. The catches of smelt near Rupelmonde during summer suggest that the Zeeschelde also functions as growing-up habitat for this species. Only a limited number of threespined sticklebacks (trachurus) were caught during the study. However, previous studies near the weir in Merelbeke showed that the upstream migration of sticklebacks occurs between January and April. The migration peak was possibly missed because of the limited temporal resolution of the sampling strategy. Only a few adult twaite shads were caught in the brackish part of the Zeeschelde. The low number of adults and the absence of 0+ individuals indicates that twaite shad does not yet reproduce in the Schelde. Our results clearly show that the main migration route of anadromous fishes in the Schelde is towards the Upper Schelde/River Leie. On the migration axis through the Rupel, on the other hand, almost no anadromous species were caught. From March 2007 on, the sewage treatment plant of Brussels became operational, which greatly improved the water quality in the River Rupel. For the moment, however, only flounder and eel seem to benefit from the increased oxygen concentration. Their numbers increased exponentially in the Rupel during the second half of 2008. Probably, the oxygen concentration is still too low for the other diadromous species or the stimulus for upstream migration is lacking (e.g. conspecific odours in river lampreys). A number of diadromous species does not occur anymore in the Schelde basin. Until the first half of the 19 th century, a stable and reproducing copulation of allis shad occurred in the Schelde basin, but they became extinct locally by the beginning of the 20 th century. For other species like Atlantic salmon, sea trout, Atlantic sturgeon and houting, we have less information about the historical status of their populations in the Schelde. Already in the Middle Ages the populations of these species were seriously threatened, which makes natural recovery unlikely to occur. Monitoring The three sampling methods that were applied in this project (cooling water, intertidal and subtidal fykes) proved to be complementary and each are useful to describe a different aspect of the migration of diadromous fishes. The volunteer network (intertidal fykes) has a high temporal and spatial resolution. Especially the catadromous species that use the estuary as a foraging and nursery area, were caught in the intertidal fyke nets. Subadult shads and downstream migrating juvenile lampreys were only caught in the cooling water of the powerplant of Doel. In addition, the fish monitoring of the cooling water in Doel started in 1991, which allows us to investigate long-term trends. The subtidal fyke nets that were deployed underneath the migration barriers proved to be efficient in catching the fishes during their spawning run. During their upstream migration, anadromous fishes accumulate underneath the barriers where they can be caught in large numbers. The proposed monitoring programme consists of a combination of the above sampling methods. We advise to continue the monthly sampling of the cooling water and to build on seven sampling locations of the volunteer network in the estuary. An extra volunteer sampling station near the Dutch-Belgian border and, if possible, a volunteer network in the Westerschelde should be set up in order to cover the complete estuarine gradient. In addition, the possibility should be investigated of fishing with stow nets at about three locations in the Zeeschelde. In this way, the Dutch and Belgian monitoring programmes can be harmonised and diadromous fishes that migrate through the main channel will be sampled more efficiently. Each fish barriers on the main migration routes that is being solved, should be fitted with a device for capturing migrating diadromous fishes. As long as those devices are in not place, the present fyke net monitoring should be continued at the barriers on the Upper Schelde, Leie and Kleine Nete. Finally, the glass eel monitoring by a volunteer in the Zeeschelde should be maintained and further supported. This monitoring proposal for diadromous fishes is part of the integrated monitoring plan for the Schelde estuary (MONEOS).Sampling
The three sampling methods that were applied in this project (cooling water, intertidal and subtidal fykes) proved to be complementary and each are useful to describe a different aspect of the migration of diadromous fishes. The volunteer network (intertidal fykes) has a high temporal and spatial resolution. Especially the catadromous species that use the estuary as a foraging and nursery area, were caught in the intertidal fyke nets. Subadult shads and downstream migrating juvenile lampreys were only caught in the cooling water of the powerplant of Doel. In addition, the fish monitoring of the cooling water in Doel started in 1991, which allows us to investigate long-term trends. The subtidal fyke nets that were deployed underneath the migration barriers proved to be efficient in catching the fishes during their spawning run. During their upstream migration, anadromous fishes accumulate underneath the barriers where they can be caught in large numbers.Quality Control
All records are validated.Method steps
- The proposed monitoring programme consists of a combination of the above sampling methods.
Taxonomic Coverages
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Actinopterygiicommon name: ray-finned fishes rank: class
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Abramis bramacommon name: common bream rank: species
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Agonus cataphractuscommon name: pogge rank: species
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Alburnus alburnuscommon name: common bleak rank: species
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Ameiurus nebulosuscommon name: brown bullhead rank: species
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Anguilla anguillacommon name: European eel rank: species
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Atherina presbytercommon name: sand smelt rank: species
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Barbatula barbatulacommon name: stone loach rank: species
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Blicca bjoerknacommon name: silver bream rank: species
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Carassius gibeliocommon name: Prussian carp rank: species
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Carcinus maenasrank: species
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Ciliata mustelacommon name: fivebeard rockling rank: species
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Clupea harenguscommon name: Atlantic herring rank: species
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Cobitis taeniacommon name: spined loach rank: species
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Cottus gobiocommon name: European bullhead rank: species
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Cyprinus carpiocommon name: common carp rank: species
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Dicentrarchus labraxcommon name: European seabass rank: species
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Eriocheir sinensiscommon name: Chinese mitten crab rank: species
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Esox luciuscommon name: northern pike rank: species
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Gadus morhuacommon name: Atlantic cod rank: species
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Gasterosteus aculeatuscommon name: three-spined stickleback rank: species
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Gobio gobiocommon name: gudgeon rank: species
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Gymnocephalus cernuuscommon name: Eurasian ruffe rank: species
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Hyperoplus lanceolatuscommon name: greater sand eel rank: species
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Lampetra fluviatiliscommon name: European river lamprey rank: species
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Lampetra planericommon name: European brook lamprey rank: species
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Lepomis gibbosuscommon name: pumpkinseed rank: species
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Leuciscus cephaluscommon name: European chub rank: species
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Leuciscus iduscommon name: ide rank: species
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Leuciscus leuciscuscommon name: common dace rank: species
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Liparis lipariscommon name: common seasnail rank: species
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Liza ramadacommon name: thinlip mullet rank: species
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Lota lotacommon name: burbot rank: species
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Osmerus eperlanuscommon name: European smelt rank: species
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Perca fluviatiliscommon name: European perch rank: species
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Pimephales promelascommon name: fathead minnow rank: species
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Platichthys flesuscommon name: European flounder rank: species
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Pomatoschistus micropscommon name: common goby rank: species
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Pomatoschistus minutuscommon name: sand goby rank: species
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Pseudorasbora parvacommon name: stone moroko rank: species
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Pungitius pungitiuscommon name: ninespine stickleback rank: species
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Rhodeus amaruscommon name: European bitterling rank: species
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Rutilus rutiluscommon name: common roach rank: species
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Salmo truttacommon name: brown trout rank: species
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Sander luciopercacommon name: zander rank: species
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Scardinius erythrophthalmuscommon name: common rudd rank: species
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Silurus glaniscommon name: wels catfish rank: species
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Solea soleacommon name: common sole rank: species
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Syngnathus acuscommon name: greater pipefish rank: species
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Tinca tincacommon name: tench rank: species
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Trisopterus luscuscommon name: pouting rank: species
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Umbra pygmaeacommon name: eastern mudminnow rank: species
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Cephalaspidomorphirank: class
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Malacostracarank: class
Geographic Coverages
Bibliographic Citations
- Stevens, M. et al. (2009). Onderzoek naar de trekvissoorten in het stroomgebied van de Schelde. Rapport van het Instituut voor Natuur- en Bosonderzoek, R.2009.9. Instituut voor Natuur- en Bosonderzoek: Brussel, Belgium. 188 pp. -
Contacts
Maarten Stevensoriginator
position: Researcher
Research Institute for Nature and Forest (INBO)
Kliniekstraat 25
Brussels
1070
Brussels Capital Region
BE
email: maarten.stevens@inbo.be
Maarten Stevens
metadata author
position: Researcher
Research Institute for Nature and Forest (INBO)
Kliniekstraat 25
Brussels
1070
Brussels Capital Region
BE
email: maarten.stevens@inbo.be
Maarten Stevens
point of contact
position: Researcher
Research Institute for Nature and Forest (INBO)
Kliniekstraat 25
Brussels
1070
Brussels Capital Region
BE
email: maarten.stevens@inbo.be
Johan Coeck
author
position: Researcher
Research Institute for Nature and Forest (INBO)
Kliniekstraat 25
Brussels
1070
Brussels Capital Region
BE
email: johan.coeck@inbo.be
Dimtiri Brosens
processor
position: Data liaison officer
Research Institute for Nature and Forest (INBO)
Kliniekstraat 25
Brussels
1070
Brussels Capital Region
BE
email: dimitri.brosens@inbo.be
homepage: http://www.biodiversity.be
Maarten Stevens
administrative point of contact
position: Researcher
Research Institute for Nature and Forest (INBO)
Kliniekstraat 25
Brussels
1070
Brussels Capital Region
BE
email: maarten.stevens@inbo.be