References of "Ovidio, Michaël"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailThe impact of small physical obstacles on upstream movements of six species of fish - Synthesis of a 5-year telemetry study in the River Meuse basin
Ovidio, Michaël ULg; Philippart, Jean-Claude ULg

in Hydrobiologia (2002), 483(1-3), 55-69

In the course of the 'Meuse Salmon 2000' programme, most weirs and dams (3-8 m in height) in the regulated River Meuse have been progressively equipped with new fishways in order to restore the free ... [more ▼]

In the course of the 'Meuse Salmon 2000' programme, most weirs and dams (3-8 m in height) in the regulated River Meuse have been progressively equipped with new fishways in order to restore the free circulation of all amphibiotic fish species. Nevertheless, fish entering into major spawning tributaries are still confronted with various kinds of physical obstacles of which the overall impact on fish migration has never been investigated. In order to test their ability to negotiate physical obstacles, 128 individuals of fish ( Salmo trutta, Thymallus thymallus, Salmo salar, Chondrostoma nasus, Barbus barbus and Esox lucius) were captured several weeks before their spawning migrations and tagged with radio-transmitters. They were tracked from 30 to 466 days in the River Ourthe and six spawning tributaries over the period October 1995 to June 2001. All obstacles recorded in this study have been classified according to their type and main characteristics (i.e. slope, length and height). Results indicated that most fish migrate during or outside the spawning period and that some small obstacles are not as insignificant as initially thought and can significantly disrupt and/or obstruct their upstream movements. There is a need to harmonize interests in the sustainable conservation of fish populations and the development of small-scale hydropower generation and tourism. [less ▲]

Detailed reference viewed: 114 (24 ULg)
Full Text
Peer Reviewed
See detailInfluence of sexual genotype on the behaviour of females (genotype WZ) and pseudofemales (genotype ZZ) in the tilapia Oreochromis aureus
Ovidio, Michaël ULg; Desprez, Damien; Mélard, Charles ULg et al

in Aquatic Living Resources (2002), 15(3), 163-167

17alpha-ethynylestradiol sex-reversed males of Oreochromis aureus (pseudofemales, DeltaF, genotype ZZ) are used in aquaculture to produce a male monosex population by crossing with ZZ homogametic normal ... [more ▼]

17alpha-ethynylestradiol sex-reversed males of Oreochromis aureus (pseudofemales, DeltaF, genotype ZZ) are used in aquaculture to produce a male monosex population by crossing with ZZ homogametic normal males. When placed with males (M) and females (F) in the same spawning tank, the spawning rate of F is higher than for DeltaF. In order to understand this phenomenon, comparisons were made between the behaviour of 18 F (446 +/- 96 mm) and 18 DeltaF (401 +/- 59 mm). DeltaF showed a more aggressive behaviour and were significantly more dominant than normal F in fighting pair experiments (F x DeltaF) or in fighting group experiments in four different stocking densities (8, 12, 16 and 83 fish 10(-3) l with F/DeltaF ratio = 1). DeltaF were also more aggressive towards males than F were. The results support the idea that behavioural differences exist between F and DeltaF These differences are probably due to the effect of the sexual genotype on behaviour. (C) 2002 Ifremer/CNRS/Inra/IRD/Cemagref/Editions scientifiques et medicales Elsevier SAS. All rights reserved. [less ▲]

Detailed reference viewed: 38 (6 ULg)
Full Text
Peer Reviewed
See detailSeasonal variations of activity pattern of brown trout (Salmo trutta) in a small stream, as determined by radio-telemetry
Ovidio, Michaël ULg; Baras, Etienne; Goffaux, D. et al

in Hydrobiologia (2002), 470(1-3), 195-202

Nine brown trout (27.9-42.8 cm FL, 234-995 g) from the Aisne stream (Belgian Ardenne) were tagged with surgically implanted radio transmitters, and their activity patterns were studied at 10-min intervals ... [more ▼]

Nine brown trout (27.9-42.8 cm FL, 234-995 g) from the Aisne stream (Belgian Ardenne) were tagged with surgically implanted radio transmitters, and their activity patterns were studied at 10-min intervals during twenty-six 24-h cycles from October 1995 to May 1997. The duration and intensity of activity were mainly proportional to water temperature and day length but some differences appeared between individuals. The daily home range in summer was also 3.2 times longer than in winter, and was exploited 2.5 times more intensively. At all seasons, trout were most active at dusk, and seasonal variations in diel patterns consisted mainly in a progressive shift from more crepuscular activity in autumn and winter to more homogenous and intensive activity during spring and summer, but still with a predominance of activity at dusk. This relative consistency of activity rhythm throughout the year was interpreted within the context of foraging risk and efficiency, in view of the scarcity of predators in the Aisne stream, and of drifting macroinvertebrates being consistently more abundant at dusk at all times of the year. However, activity patterns varied substantially between individuals living in different microhabitats, including when fish were investigated on the same day. This suggests that activity patterns are also subordinated to local factors such as habitat structure or abundance of drifting prey. [less ▲]

Detailed reference viewed: 51 (14 ULg)
Full Text
See detailL'impact des barrages sur les migrations des poissons
Ovidio, Michaël ULg

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

Detailed reference viewed: 75 (7 ULg)
Full Text
Peer Reviewed
See detailA radio-tracking study on the impact of small dams on the conservation of salmonid fish in Southern Belgium.
Ovidio, Michaël ULg; Lambot, Francis; DeBast, Benoît et al

Conference (2000, November)

Detailed reference viewed: 23 (5 ULg)
Full Text
Peer Reviewed
See detailRelationship between habitat structure and the mobility of brown trout in a small stream.
Ovidio, Michaël ULg; Brucy, Claire; Philippart, Jean-Claude ULg et al

Conference (2000, September)

Detailed reference viewed: 15 (2 ULg)