Acomprehensive assessment of the failure of barbus barbus spawning migrations through a fish pass in the canalized river meuse (Belgium) / Baras, Etienne

Public ISBD Faire une suggestion d'achat Titre : Acomprehensive assessment of the failure of barbus barbus spawning migrations through a fish pass in the canalized river meuse (Belgium) Type de document : texte imprimé Auteurs : Baras, Etienne, Auteur Importance : pp. 181-189 Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : This paper presents a comprehensive study of the impact of damming on the spawning migrations of Barbus barbus in the canalized River Meuse (Southern Belgium). A Denil fish pass on the Ampsin-Neuville dam was controlled 251 times in 1989-1993. The most striking feature is the almost complete absence of barbel in 1990-1993 (15 fishes in 4 years). Most captures of barbel in the fish pass in 1989 were clumped within a few days (mid-May) and related with spawning migrations. Stepwise multiple regression analyses revealed that attractivity was the major condition set allowing barbel to migrate successfully through the pass, while feasibility parameters (water velocity) were found not to be relevant. The variables involved in the attractivity condition set refer indirectly to the influence of water catchment by a hydroelectric plant and to the relative importance of the flow in the pass. The study concludes that this additional condition set significantly interferes with the natural environmental stimuli triggering spawning migrations in barbel and questions the effectiveness of the thermally-related reproductive strategy of the species in an environment with restricted longitudinal connectivity. This statement is discussed in parallel with the recent evolution of barbel populations in canalized rivers. Acomprehensive assessment of the failure of barbus barbus spawning migrations through a fish pass in the canalized river meuse (Belgium) [texte imprimé] / Baras, Etienne, Auteur . - [s.d.] . - pp. 181-189. Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : This paper presents a comprehensive study of the impact of damming on the spawning migrations of Barbus barbus in the canalized River Meuse (Southern Belgium). A Denil fish pass on the Ampsin-Neuville dam was controlled 251 times in 1989-1993. The most striking feature is the almost complete absence of barbel in 1990-1993 (15 fishes in 4 years). Most captures of barbel in the fish pass in 1989 were clumped within a few days (mid-May) and related with spawning migrations. Stepwise multiple regression analyses revealed that attractivity was the major condition set allowing barbel to migrate successfully through the pass, while feasibility parameters (water velocity) were found not to be relevant. The variables involved in the attractivity condition set refer indirectly to the influence of water catchment by a hydroelectric plant and to the relative importance of the flow in the pass. The study concludes that this additional condition set significantly interferes with the natural environmental stimuli triggering spawning migrations in barbel and questions the effectiveness of the thermally-related reproductive strategy of the species in an environment with restricted longitudinal connectivity. This statement is discussed in parallel with the recent evolution of barbel populations in canalized rivers.

Exemplaires(0)

Disponibilité
aucun exemplaire

Day-night alternation prevails over food availability in synchronising the activity of Piaractus brachypomus (Characidae) / Baras, Etienne

Public ISBD Faire une suggestion d'achat Titre : Day-night alternation prevails over food availability in synchronising the activity of Piaractus brachypomus (Characidae) Type de document : texte imprimé Auteurs : Baras, Etienne, Auteur Importance : pp. 115-120 Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : Pirapatinga given submaximal rations grow faster when fed at night than when fed during daylight hours. It was hypothesised that these fish were day-night conformers, with a nocturnal acrophase, and expended more energy during daytime feeding. In order to test this hypothesis, telemetry was applied to study the behaviour of cultured pirapatinga (stocking biomass of 40 kg·m-3; 27 ± 1°C; 6 mg 02-L-1; 13.5 UIO.5 0) under three feeding schedules (diurnal versus nocturnal feeding [12 g·d-I·fish-I over 10 h] versus fasting) that were evaluated in succession over I week each. This implied a feasibility study to test the adequacy of tagging fish with surgically implanted transmitters (ventrolateral incision, posterior to the pelvic girdle). There was no mortality or tag loss over 12 months following surgery, and abdominal incisions healed within 4 weeks. Under all three feeding schedules, activity increased at dawn, peaked during daytime, decreased at twilight and reached a minimum during the late night. Diurnal and twilight activity levels were similar under all three schedules, whereas nocturnal activity was significantly lower with daytime feeding. These observations indicate that pirapatinga have a diurnal activity acrophase, which is little influenced by food availability, and imply that the higher growth of fish fed at night does not originate from lower energetic expenditures. Day-night alternation prevails over food availability in synchronising the activity of Piaractus brachypomus (Characidae) [texte imprimé] / Baras, Etienne, Auteur . - [s.d.] . - pp. 115-120. Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : Pirapatinga given submaximal rations grow faster when fed at night than when fed during daylight hours. It was hypothesised that these fish were day-night conformers, with a nocturnal acrophase, and expended more energy during daytime feeding. In order to test this hypothesis, telemetry was applied to study the behaviour of cultured pirapatinga (stocking biomass of 40 kg·m-3; 27 ± 1°C; 6 mg 02-L-1; 13.5 UIO.5 0) under three feeding schedules (diurnal versus nocturnal feeding [12 g·d-I·fish-I over 10 h] versus fasting) that were evaluated in succession over I week each. This implied a feasibility study to test the adequacy of tagging fish with surgically implanted transmitters (ventrolateral incision, posterior to the pelvic girdle). There was no mortality or tag loss over 12 months following surgery, and abdominal incisions healed within 4 weeks. Under all three feeding schedules, activity increased at dawn, peaked during daytime, decreased at twilight and reached a minimum during the late night. Diurnal and twilight activity levels were similar under all three schedules, whereas nocturnal activity was significantly lower with daytime feeding. These observations indicate that pirapatinga have a diurnal activity acrophase, which is little influenced by food availability, and imply that the higher growth of fish fed at night does not originate from lower energetic expenditures.

Exemplaires(0)

Disponibilité
aucun exemplaire

Environmental determinants of residence area selection by barbus barbus in the river Ourthe / Baras, Etienne

Public ISBD Faire une suggestion d'achat Titre : Environmental determinants of residence area selection by barbus barbus in the river Ourthe Type de document : texte imprimé Auteurs : Baras, Etienne, Auteur Importance : pp. 195-206 Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : A biotelemetry experiment was designed to determine whether the selection of a residence area by adult barbel Barbus barbus (Cyprinidae) was dependent on the availability of physical habitat features, on the presence of fish shoals and/or on the presence of specific partners. The experiment took place in 3.0 km stretch of the River Ourthe (Belgium), where the latter features had been characterised by habitat and electric fishing surveys (I 190 fish 15 cm, at 265 locations). Six barbel (34.8-49.5 cm) belonging to a single shoal of 34 fish were tagged with 40 MHz radio transmitters, transplanted in pairs at different distances (-I km, -30 01, + I km) from the capture site and tracked from 3 September to 7 October 1990. Fish showed variable mobility patterns and home range sizes (200-2 400 m). They selected 17 residence areas of which the cumulative frequency of occupation ranged from 0.1 to 79.5 day x fish. The comparison between the residence areas selected, habitat suitability and the location of fish shoals in the study area indicate that the presence of a shoal of at least LO resident fish within a suitable habitat (normalised suitability index 1.0) is necessary but not sufficient to guarantee its long term selection and occupation. Homing movements of transplanted fish were directed towards the activity area rather than to the residence area itself. The fish that did not home, selected residence areas in a part of the river with a higher availability of potential feeding areas. These elements are discussed within the context of habitat utilisation and foraging strategies by a gregarious species. It is suggested that resident fish of the same species may ease the exploitation of a non familiar environment by a naive fish, and that this may positively trade off the benefit provided by home site fidelity, depending on the availability of food resources. Environmental determinants of residence area selection by barbus barbus in the river Ourthe [texte imprimé] / Baras, Etienne, Auteur . - [s.d.] . - pp. 195-206. Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : A biotelemetry experiment was designed to determine whether the selection of a residence area by adult barbel Barbus barbus (Cyprinidae) was dependent on the availability of physical habitat features, on the presence of fish shoals and/or on the presence of specific partners. The experiment took place in 3.0 km stretch of the River Ourthe (Belgium), where the latter features had been characterised by habitat and electric fishing surveys (I 190 fish 15 cm, at 265 locations). Six barbel (34.8-49.5 cm) belonging to a single shoal of 34 fish were tagged with 40 MHz radio transmitters, transplanted in pairs at different distances (-I km, -30 01, + I km) from the capture site and tracked from 3 September to 7 October 1990. Fish showed variable mobility patterns and home range sizes (200-2 400 m). They selected 17 residence areas of which the cumulative frequency of occupation ranged from 0.1 to 79.5 day x fish. The comparison between the residence areas selected, habitat suitability and the location of fish shoals in the study area indicate that the presence of a shoal of at least LO resident fish within a suitable habitat (normalised suitability index 1.0) is necessary but not sufficient to guarantee its long term selection and occupation. Homing movements of transplanted fish were directed towards the activity area rather than to the residence area itself. The fish that did not home, selected residence areas in a part of the river with a higher availability of potential feeding areas. These elements are discussed within the context of habitat utilisation and foraging strategies by a gregarious species. It is suggested that resident fish of the same species may ease the exploitation of a non familiar environment by a naive fish, and that this may positively trade off the benefit provided by home site fidelity, depending on the availability of food resources.

Exemplaires(0)

Disponibilité
aucun exemplaire

Feeding in darkness alleviates density-dependent growth of juvenile vundu catfish heterobranchus longifilis (Clariidae) / Baras, Etienne

Public ISBD Faire une suggestion d'achat Titre : Feeding in darkness alleviates density-dependent growth of juvenile vundu catfish heterobranchus longifilis (Clariidae) Type de document : texte imprimé Auteurs : Baras, Etienne, Auteur Importance : pp. 335-340 Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : Sibling juvenile vundu Heterobranchus longifilis reared at 27 ± 1 °C under 12L:12D were fed during the day, at night or over the entire 24-h cycle, for periods of 14-15 d. Nighttime feeding gave thé highest growth rates, best feed conversion, lowest mortality, fewest losses due to cannibalism and least growth heterogeneity. The trends were seen in fish of ail âges and weights (31-101 d and 0.3-30.0 g), but differences were significant only for the smallest fish that were reared at the lowest stocking biomass (< 3.5 g-L). The eftects of daytime and nighttime feeding were examined in 151-d old (85 g) juveniles stocked at different biomasses (3.4 and 13.6g-L). The growth of vundu was density-dependent, being impaired at low stocking density, but this was substantially mitigated under nighttime feeding. Rearing at high stocking density, feeding at night or in darkness, may act through similar mechanisms that involve changes in the level of aggressive behaviour. It is suggested that nighttime feeding in intensive catfish culture could be replaced by 24-h feeding under conditions of permanent darkness. Feeding in darkness alleviates density-dependent growth of juvenile vundu catfish heterobranchus longifilis (Clariidae) [texte imprimé] / Baras, Etienne, Auteur . - [s.d.] . - pp. 335-340. Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : Sibling juvenile vundu Heterobranchus longifilis reared at 27 ± 1 °C under 12L:12D were fed during the day, at night or over the entire 24-h cycle, for periods of 14-15 d. Nighttime feeding gave thé highest growth rates, best feed conversion, lowest mortality, fewest losses due to cannibalism and least growth heterogeneity. The trends were seen in fish of ail âges and weights (31-101 d and 0.3-30.0 g), but differences were significant only for the smallest fish that were reared at the lowest stocking biomass (< 3.5 g-L). The eftects of daytime and nighttime feeding were examined in 151-d old (85 g) juveniles stocked at different biomasses (3.4 and 13.6g-L). The growth of vundu was density-dependent, being impaired at low stocking density, but this was substantially mitigated under nighttime feeding. Rearing at high stocking density, feeding at night or in darkness, may act through similar mechanisms that involve changes in the level of aggressive behaviour. It is suggested that nighttime feeding in intensive catfish culture could be replaced by 24-h feeding under conditions of permanent darkness.

Exemplaires(0)

Disponibilité
aucun exemplaire

Seasonal activities of female barbel barbus barbus (L) in the river ourthe (southern belgium), as revealed by radio tracking / Baras, Etienne

Public ISBD Faire une suggestion d'achat Titre : Seasonal activities of female barbel barbus barbus (L) in the river ourthe (southern belgium), as revealed by radio tracking Type de document : texte imprimé Auteurs : Baras, Etienne, Auteur Importance : pp. 283-294 Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : Two female barbel Barhus harbus (L.) were tagged with implantahlc radio transmitters and tracked in the Ourlhc River (Southern Belgium) from April 12th to July 7th. 1989 to study their movements and activity rhythms during the spring-summer period. Both barbels defined a 1.6 km home range and occupied four residence areas. Greatest average daily movements within the home range limits occurred during the prcspawning and spawning periods and were associated with variations of mean daily water temperature and level. Barbel 2 made a 9.6 km excursion from its spring home range and homed a week later in its residence area. Barbels displayed dusk and dawn activity patterns, characterized by the occupation of riffle areas. The activity timing was found to be dependent on water temperature while the size of daily activity area was more influenced by river flow conditions. Seasonal activities of female barbel barbus barbus (L) in the river ourthe (southern belgium), as revealed by radio tracking [texte imprimé] / Baras, Etienne, Auteur . - [s.d.] . - pp. 283-294. Langues : Anglais (eng) Index. décimale : 578 Histoire naturelle des organismes vivants Résumé : Two female barbel Barhus harbus (L.) were tagged with implantahlc radio transmitters and tracked in the Ourlhc River (Southern Belgium) from April 12th to July 7th. 1989 to study their movements and activity rhythms during the spring-summer period. Both barbels defined a 1.6 km home range and occupied four residence areas. Greatest average daily movements within the home range limits occurred during the prcspawning and spawning periods and were associated with variations of mean daily water temperature and level. Barbel 2 made a 9.6 km excursion from its spring home range and homed a week later in its residence area. Barbels displayed dusk and dawn activity patterns, characterized by the occupation of riffle areas. The activity timing was found to be dependent on water temperature while the size of daily activity area was more influenced by river flow conditions.

Exemplaires(0)

Disponibilité
aucun exemplaire

Size heterogeneity prevails over kinship in shaping cannibalism among larvae of sharptooth catfish clarias gariepinus / Baras, Etienne

Permalink

---

1 (1 - 6 / 6) Par page : 25 50 100 200