The life cycle of the European eel (Anguilla anguilla) remained a mystery until the 20th century, when Schmidt discovered that the Sargasso Sea was its spawning area. However, many aspects of the eel’s life cycle remain poorly understood.... more
The life cycle of the European eel (Anguilla anguilla) remained a mystery until the 20th century, when Schmidt discovered that the Sargasso Sea was its spawning area. However, many aspects of the eel’s life cycle remain poorly understood. Among these is the bimodal distribution in head shape, with broad- and narrowheaded phenotypes reported in the yellow eel stage. Although this has been linked to dietary preferences of the yellow eels, very little is known about why, how and when this dimorphism arises during their ontogeny. To find out whether this dimorphism indeed appears in relation to trophic niche segregation, we examined head shape variation at an earlier ontogenetic stage, the glass eel stage, as at this stage, eels are considered to be non-feeding. Head shape was studied in glass eels from the Yser river mouth, the Leopold Canal and from the rivers Severn, Trent and Parret by both taking measurements (head width/head length) and using an outline analysis. Our results show that there’s already considerable variation in broadness and bluntness of the head at the glass eel stage, but no unambiguous support for head shape dimorphism was found. However, as variation in head width/head length ratios in non-feeding glass eels shows a similar range as in feeding yellow eels, head shape in European eel might be at least partially determined through other mechanisms than trophic segregation.
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The life cycle of the European eel (Anguilla anguilla) remained a mystery until the 20th century, when Schmidt discovered that the Sargasso Sea was its spawning area. However, many aspects of the eel's life cycle remain poorly... more
The life cycle of the European eel (Anguilla anguilla) remained a mystery until the 20th century, when Schmidt discovered that the Sargasso Sea was its spawning area. However, many aspects of the eel's life cycle remain poorly understood. Among these is the bimodal distribution in head shape, with broad- and narrowheaded phenotypes reported in the yellow eel stage. Although this has been linked to dietary preferences of the yellow eels, very little is known about why, how and when this dimorphism arises during their ontogeny. To determine whether this dimorphism indeed appears in relation to trophic niche segregation, we examined head shape variation at an earlier ontogenetic stage, the glass eel stage, as at this stage eels are considered to be non-feeding. Head shape was studied in a large dataset, containing glass eels captured from the Yser river mouth, the Leopold Canal (Belgium) and from the rivers Severn, Trent and Parret (UK), by both taking measurements (head width/head length) and using an outline analysis. Our results show that there is already considerable variation in broadness and bluntness of the head at the glass eel stage. In most cases, equal support for a unimodal and bimodal head shape distribution is found, whereas some cases support head shape bimodality in glass eels, suggesting that glass eel head shape might be shifting from a unimodal to a bimodal distribution. This, in combination with the observation that variation in head width/head length ratios in non-feeding glass eels shows a similar range as in feeding yellow eels, indicates that head shape in European eel might be at least partially determined through other mechanisms than trophic segregation.
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This Technical Guidance Document on Biota Monitoring (the Implementation of EQSbiota) aims to facilitate the implementation of environmental quality standards (EQS) in biota under the Water Framework Directive by addressing in particular... more
This Technical Guidance Document on Biota Monitoring (the Implementation of EQSbiota) aims to facilitate the implementation of environmental quality standards (EQS) in biota under the Water Framework Directive by addressing in particular the sampling strategies appropriate for monitoring programmes designed to assess compliance with biota EQS. It is Guidance Document No. 32 in the series of guidance documents prepared to support the Common Implementation Strategy (CIS) for the Water Framework Directive. It elaborates extensively on the content of Guidance Document No. 25 on Chemical Monitoring in Sediment and Biota under the Water Framework Directive, and is complemented by Guidance Document No. 33, the Technical Guidance Document on Analytical Methods for Biota Monitoring. Guidance Documents 32 and 33 together address the requirement for guidance on biota monitoring mentioned in Article 3(8a) of Directive 2008/105/EC as amended by Directive 2013/39/EU. The original Directive 2008/1...
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De Grote modderkruiper is een vissoort van stilstaande wateren en traagstromende beken. Ze is de laatste decennia dramatisch achteruitgegaan. Zo sterk zelfs dat men ervoor vreest dat de soort zich in Vlaanderen mogelijk op de rand van... more
De Grote modderkruiper is een vissoort van stilstaande wateren en traagstromende beken. Ze is de laatste decennia dramatisch achteruitgegaan. Zo sterk zelfs dat men ervoor vreest dat de soort zich in Vlaanderen mogelijk op de rand van uitsterven bevindt. Haar erg mysterieuze nachtelijke levenswijze maakt het erg moeilijk deze vis waar te nemen, wat een accurate inschatting van het voorkomen van deze Habitatrichtlijnsoort sterk belemmert. Via het oppikken van DNA-sporen die de soort in haar omgeving achterlaat (zogenaamd eDNA), tonen we in deze bijdrage aan dat de Grote modderkruiper toch nog op meer plaatsen aanwezig is dan aanvankelijk gedacht. We bespreken ook de mogelijkheden van de ontwikkelde eDNA-techniek voor het opsporen van andere soorten.
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The European eel (Anguilla anguilla (L).) is a widespread species in decline and current fisheries are considered outside sustainable limits. The European Commission has proposed that the primary instrument for management of European eel... more
The European eel (Anguilla anguilla (L).) is a widespread species in decline and current fisheries are considered outside sustainable limits. The European Commission has proposed that the primary instrument for management of European eel should be the development by Member States of "Eel Management Plans" including putting in place monitoring actions for the EU Data Collection Regulation. A research project proposal has been submitted to the Belgian Research programme “Science for a Sustainable Development”. Partners involved are institutes and universities in Flanders and Wallonia. The project is entitled “Progressive extinction of the eel: biological basis for a national recovery plan” and has the acronym ”EELBASE”. The objective is setting the scientific base for the development of the national Eel Management Plans by developing an eel database (EELBASE), designing a Belgian eel restocking programme and collecting new data about the key factors affecting the eel stocks throughout Belgium. Field studies in selected basins will focus on ecological aspects including habitat evaluation of yellow eel, silver eel escapement and impact of turbines and pumps. Another objective is to evaluate interactions between the different environmental and physiological parameters by means of an extensive assessment of physiological traits of eels of polluted and unpolluted sites. For this, several aspects of health and condition of local pre-silver and silver eel populations will be studied (a series of physiological parameters, quality of gametes, parasitological and viral agents, …).Keywords: European eel, Anguilla anguilla, management, stocks, migration, physiologyPeer reviewe
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European eel (Anguilla anguilla) recruitment has been declining at least since the early 1980s at the scale of its distribution area. Since the population is panmictic, its stock assessment should be carried out on a range-wide basis.... more
European eel (Anguilla anguilla) recruitment has been declining at least since the early 1980s at the scale of its distribution area. Since the population is panmictic, its stock assessment should be carried out on a range-wide basis. However, assessing the overall stock during the continental phase remains difficult given its widespread distribution among heterogeneous and separate river catchments. Hence, it is currently considered by the International Council for the Exploration of the Sea (ICES) more feasible to use glass eel recruitment data to assess the status of the overall population. In this study, we used Glass Eel Recruitment Estimation Model (GEREM) to estimate annual recruitment (i) at the river catchment level, a scale for which data are available, (ii) at an intermediate scale (6 European regions), and (iii) at a larger scale (Europe). This study provides an estimate of the glass eel recruitment trend through a single index, which gathers all recruitment time-series ...
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The first fish-based index to assess the ecological quality of lowland rivers in Flanders (Belgium) is based on data obtained from different fishing techniques without considering the gear specificity. As a consequence, this index could... more
The first fish-based index to assess the ecological quality of lowland rivers in Flanders (Belgium) is based on data obtained from different fishing techniques without considering the gear specificity. As a consequence, this index could not be intercalibrated with other European indices which concentrate on one gear type only. In order to comply with the European Water Framework Directive, we developed a new fish-based index using data obtained from surveys in rivers with electric gear only. All 293 selected rivers belonged to the bream or barbel zone. An updated reference list of fish species was compiled based on previous work and recent data. Abiotic data were collected according to standard methods and habitat quality of all surveyed sites was pre-classified using pressure indicators. To develop the new index candidate metrics were selected from the literature and metric values were calculated. Linear mixed regression models selected metrics based on their response to the pre-cl...
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1 Department of Public Health, Ghent University, UZ 2 Blok A, De Pintelaan 185, B-9000 Ghent, Belgium 2 Department of Food Safety and Food Quality, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium 3 Centre for Environmental... more
1 Department of Public Health, Ghent University, UZ 2 Blok A, De Pintelaan 185, B-9000 Ghent, Belgium 2 Department of Food Safety and Food Quality, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium 3 Centre for Environmental Sciences, Hasselt University, Campus Diepenbeek, Agoralaan, B-3590 Diepenbeek, Belgium 4 Institute for Forestry and Game Management, Duboislaan 14, B-1560 Groenendaal-Hoeilaart, Belgium
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Research Interests: Zoology, Biology, Ecology, Fish Biology, Medicine, and 4 morePredation, Fisheries Sciences, Fishery, and Crustacean
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Roose, P.; Van Thuyne, G.; Belpaire, C.; Raemaekers, M.; Brinkman, UA Th.(2008). Volatile organic compounds in yellow eel, in: Belpaire, C.(2008). Verontreiniging in paling: een oorzaak van zijn achteruitgang?= Pollution in eel: a cause... more
Roose, P.; Van Thuyne, G.; Belpaire, C.; Raemaekers, M.; Brinkman, UA Th.(2008). Volatile organic compounds in yellow eel, in: Belpaire, C.(2008). Verontreiniging in paling: een oorzaak van zijn achteruitgang?= Pollution in eel: a cause of their decline?. INBO, M. ...
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At least eighteen non-indigenous freshwater fish species were reported to occur in the wild within the territory of Flanders. Nine are considered naturalized while the others are acclimatized and do not form self sustaining populations.... more
At least eighteen non-indigenous freshwater fish species were reported to occur in the wild within the territory of Flanders. Nine are considered naturalized while the others are acclimatized and do not form self sustaining populations. Nine of the introductions occurred prior to 1950, with the other nine species introduced since then. This contribution reviews the available information on these introductions, and evaluates a decade of data from fisheries surveys to assess the recent development of these non-indigenous populations. ...