Monitoring the biodiversity and population ecology of fish in the Belgian Meuse Rivier by the use of fishpasses. A 12-year study at the Visé-Lixhe dam.

Conference (2001, December)

Diel activity of Sarpa salpa (Sparidae) by ultrasonic telemetry in a Posidonia Oceanica meadow of Corsica (Mediterranean sea).

Conference (2001, June)

Le rétablissement de la libre circulation des poissons dans la Meuse canalisée navigable en Wallonie. Construction d'ouvrages modernes de franchissement des barrages et évaluation scientifique de leur efficacité.

Conference (2001, April)

L'impact des barrages sur les migrations des poissons

in Delbeuck, Claude (Ed.) Paysage (2001)

A radio-tracking study on the impact of small dams on the conservation of salmonid fish in Southern Belgium.

Conference (2000, November)

Methodological bias in home range and mobility estimates when locating radio-tagged trout, Salmo trutta, at different time intervals

in Aquatic Living Resources (2000), 13(6), 449-454

Radio tracking has been extensively used to enhance our knowledge on the movement and home range of fish in general and salmonids in particular. However, the use of various temporal sampling protocols is ... [more ▼]

Radio tracking has been extensively used to enhance our knowledge on the movement and home range of fish in general and salmonids in particular. However, the use of various temporal sampling protocols is likely to overlook fish movements, and produce experimental artefacts, the amplitude of which is unknown and may compromise comparison of fish behaviours revealed by different protocols. Starting from a day-by-day tracking study of brown treat in Belgian waters (Aisne stream, nine fish, minimum 39 daily locations per fish), we re-examined their home range and mobility, through a subsampling process, as if the fish had been located at longer time intervals (2-14 days). The estimates from subsamples were compared to the original data set in order to quantify the corresponding reduction of accuracy from observed data, and how far this could be predicted on the basis of locating frequency. The results clearly indicate that all intervals longer than one day generally generate substantial biases (reduction of accuracy from 0 to 82% for home range and from 5 to 92% for mobility) but these can be partly corrected through the use of predictive models. This analysis demonstrates that any comparison between studies relying on different locating frequencies can generate some ambiguity when interpreting biological phenomena or geographical differences. (C) 2000 Ifremer/CNRS/INRA/IRD/Cemagref/Editions scientifrques et medicales Elsevier SAS. [less ▲]

Le comportement migrateur des poissons en Wallonie. Caractérisation biologique et implication pour une gestion durable des populations.

Conference (1999, November)

Annual activity cycle of adult brown trout (Salmo trutta L.): A radio-telemetry study in a small stream of the Belgian Ardenne

in Bulletin Français de la Pêche et de la Pisciculture (1999), (352), 1-18

During a study period of 26 months, twenty trout (26.0-57.0 cm FL; 198-1,685 g) were daily located from 16 to 466 days in a small stream of the Belgian Ardenne, the Aisne stream (tributary of the river ... [more ▼]

During a study period of 26 months, twenty trout (26.0-57.0 cm FL; 198-1,685 g) were daily located from 16 to 466 days in a small stream of the Belgian Ardenne, the Aisne stream (tributary of the river Ourthe) in order to characterize their annual pattern of mobility. Daily movements were more frequent and longer during the spawning period (October-December) than at any other time of the year. Upstream migrations (max.: 25 km) generally occurred during October and the first fortnight of November and were triggered by a combination of Variations of water temperature and water level within a thermal range of 10-14 degrees C. Spawning activity (second fortnight of November until late December) took place in the Aisne stream (max. width : 10 m) or in its small tributaries. Trout surviving spawning undertook a fast (max.:9,200 m in 24 h) and precise post reproductive homing. From winter to summer, daily movements were shorter and mainly corresponded to changes of residences within a home range of which the size was proportional to the trout's size. In March and June, some trout made long upstream unidirectional migrations of which the biological signification is still unknown. These results are discussed within the context of life history strategies and management of trout populations. [less ▲]

Etude par radio-pistage des stratégies d’utilisation de l’espace par la truite commune (Salmo trutta L.) dans un petit cours d’eau des Ardennes belges.

Conference (1998, June)

Environmental unpredictability rules the autumn migration of brown trout (Salmo trutta L.) in the Belgian Ardennes

in Hydrobiologia (1998), 372

This telemetry study aimed to document the mobility of Salmo trutta in the River Ourthe sub-basin (tributary of the River Meuse) during summer and autumn, and to analyse the environmental factors which ... [more ▼]

This telemetry study aimed to document the mobility of Salmo trutta in the River Ourthe sub-basin (tributary of the River Meuse) during summer and autumn, and to analyse the environmental factors which trigger spawning migration or limit their extension. Nine trout (233-2217 g and 26.6-55.2 cm FL) were radio-tagged with intraperitoneal radio transmitters and positioned daily, from 14 August 1996 to 15 January 1997. Until 1 October, fish showed restricted movements: daily journeys never exceeded 300 m and corresponded to displacements by high floods or to routine home range movements. From 7 October to 15 November, seven of the nine trout travelled upstream over distances from 5.6 to 22.95 km, into tributaries and sub-tributaries. Migration speed was fast during the early days, when trout could travel over more than 5 km per night, then progressively decreased as they were approaching putative spawning redds under lower temperature. Both ire the River Ourthe and in the Aisne stream, all migrations started within less than three weeks (early October) and were found to be triggered by the combination of three environmental factors: high variations of water temperature and water level between consecutive days, within a thermal range of 10-12 degrees C. From the trout point's of view, these may be signs that the environment becomes unpredictable, as its variability increases within a thermal range which no longer enables them to achieve high growth rates. These results are discussed within the context of foraging strategies, life history strategies and management of trout population. [less ▲]