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Stratégies d'utilisation l'habitat par les alevins post-emergent de truite commune (Salmo trutta) et de seaumon Atlantique (Salmo salar)

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Abstract

Des observations réalisées en fluvarium pendant les deux semaines suivant l'émergence d'alevins de truite commune (Salmo trutta) et de saumon Atlantique (S. salar), montrent que ces deux espèces développent des stratégies différentes d'utilisation de l'habitat. Les alevins de saumon sont fortement inféodés au substrat, ils passent l'essentiel de leur temps au contact du fond et les tentatives de captures de proies et les comportements agressifs sont rares. Les alevins de truite occupent rapidement un poste de chasse où ils se tiennent en nage statique, bien détachés du substrat, les tentatives de captures de proies et les comportements agressifs sont beaucoup plus fréquents. Ces différences sont discutées en fonction de l'habitat sélectionné par les deux espèces à ce stade de développement.
... Cependant, plusieurs études révèlent que les émergents sont capables de supporter de telles vitesses (Heggenes et Traaen, 1988 ;Gaudin et Heland, 1995 (Heggenes et Traaen, 1988 ;Ojanguren et Brana, 2000). Finalement, même si ces 80% peuvent paraître importants, les densités finales retrouvées dans les biefs à la fin des expériences sont conforment aux densités observées sur le terrain et dans les autres expériences (Mortensen, 1977;Heland, 1980a;Ottaway et Clarke, 1981;Ottaway et Forrest, 1983;Crisp 1991;Crisp et Hurley 1991a, b;Elliott 1994). ...
... The 120 low velocity value corresponded to a low fish dispersal rate (Ottaway & Clarke, 1981). The 121 high velocity value matched observed values on spawning sites (Haury et al., 1991) but such 122 velocities was generally avoided by newly emerged fish (Gaudin et al., 1995;Heggenes et al., 123 2002). 124 ...
... This could imply that low velocity (12.0 m.s -1 ) was already too fast to be 329 withstood by fish. However, newly emerged fish naturally experience comparable velocities 330 (Gaudin & Heland, 1995), can swim in snout velocities of 15 cm.s -1 (for at least 15 min. at a 331 temperature of more than 12.4°C (Heggenes & Traaen, 1988) and dispersed more at both 332 higher (Ottaway & Clarke, 1981;Crisp & Hurley, 1991a) and lower velocities (Crisp & 333 Hurley 1991a). ...
Thesis
Cerner les facteurs responsables des structures spatiales et temporelles des communautés est une question centrale en écologie. Je me suis intéressé à l'intégration de la dimension temporelle dans l'étude des relations entre les organismes aquatiques d`eau courante et leur environnement. Cette approche m`a permis de montrer, pour la première fois dans les écosystèmes des grands fleuves, l'effet du changement climatique sur les structures des peuplements de poissons et d'invertébrés. Un travail réalisé à l'échelle de la population a apporté une vue nouvelle sur l'effet des forts débits hivernaux sur les populations de truites communes. Un travail expérimental réalisé à l'échelle de l'individu à permis de mieux comprendre les mécanismes d'influence des vitesses de courant sur la dévalaison des jeunes truites émergentes. Finalement, j'ai pu montrer qu'il pouvait exister des effets contradictoires de l'environnement sur les organismes à différentes échelles biologiques et temporelles.
... The low velocity value corresponded to a low fish displacement rate (Ottaway & Clarke, 1981). The high velocity value matched observed values on spawning sites (Haury et al., 1991), but such velocities were generally avoided by newly emerged fishes (Gaudin et al., 1995;Heggenes et al., 2002). To control velocity change, before each experiment, additional measurements were taken in the experimental channel at velocities ranging from low to high. ...
... This could mean that the low velocity (12Á0 cm s À1 ) was already too fast to be withstood by the fish. Newly Table I emerged fish, however, naturally experience comparable velocities (Gaudin et al., 1995) and roughness of the substratum probably allowed fish to shelter in 'dead' water zones (Crisp & Hurley, 1991a). In addition, greater displacement rates were observed at both lower and higher velocities (Ottaway & Clarke, 1981;Crisp & Hurley, 1991a), indicating that displacement could not be only attributed to swimming abilities (Crisp & Hurley, 1991a). ...
Article
Brown trout Salmo trutta were introduced at hatching into distinct sections of two parallel artificial channels, one with a constant low velocity (control) and one with velocity changes (experimental), at such times as to produce 12, 3 and 0 day old fish (age after emergences) when the velocity was changed in the experimental channel. This experimental design was repeated in 2002 and 2003 at comparable dates. Young brown trout were sensitive to an increased water velocity for 5 to 6 days after emergence. Water velocity modified the displacement patterns qualitatively but not quantitatively. Eighty per cent of fish moved downstream at all water velocities. Velocity changes, however, advanced the time by which 80% of the fish had displaced downstream.
... We chose 50% because it is most commonly used in the literature [24,25]. Feed specifically developed for trout (Neo supra S, AL1; Le Gouessant) was given just after emergence twice daily (9.00 a.m. and 2.00 p.m.) [30,31]. ...
Thesis
D’après le dernier rapport du groupe d'experts intergouvernemental sur l'évolution du climat (GIEC), le réchauffement climatique devrait se poursuivre au cours du siècle prochain. La température atmosphérique moyenne pourrait augmenter de 0,3°C à 4,8°C avec des valeurs extrêmes allant de 1°C à 6°C en 2100. Ces changements de température auront des conséquences directes et indirectes sur l’ensemble de la biodiversité et plus particulièrement sur les poissons qui sont des animaux poïkilothermes. Dans cette étude, trois espèces ont été choisies en prenant en compte leur stratégie de reproduction et leur différence de tolérance thermique : la truite commune (Salmo trutta), le brochet (Esox lucius) et la carpe commune (Cyprinus carpio). Nous avons, pour chacune des trois espèces, appliqué les mêmes différences de température par rapport à leur température de référence (-4, -2, Tref, +2, +4°C) et étudié les effets sur la survie et le développement des embryons et des larves au cours de l’ensemble de la période d’alimentation endogène. Ce travail a confirmé la loi générale de l’impact de la température sur la période d’incubation (Q10 ~3). La truite commune montre une forte diminution de sa survie lors d’une augmentation de quatre degrés, néanmoins les larves survivantes sont plus grandes et ont un contenu énergétique plus important. La survie des larves de brochet augmente avec la température, ces larves sont les plus grandes et leur contenu énergétique est plus important à la température la plus élevée. La survie de la carpe n’est pas affectée par la température ; néanmoins les larves élevées à basse température sont les plus petites et présentent un faible contenu énergétique. Les résultats de survie pour les premiers stades de vie sont en concordance avec les modélisations des aires de répartition actuelle. Dans le futur, la prise en compte de la niche thermique théorique des premiers stades de vie pourrait permettre d’affiner les prévisions des aires de répartition
... We chose 50% because it is most commonly used in the literature [24,25]. Feed specifically developed for trout (Neo supra S, AL1; Le Gouessant) was given just after emergence twice daily (9.00 a.m. and 2.00 p.m.) [30,31]. ...
Article
Full-text available
Temperature is the main abiotic factor that influences the life cycle of poikilotherms. The present study investigated the thermal tolerance and phenotypic plasticity of several parameters (development time, morphometric measures, bioenergetics) for both embryos and fry of a cold stenothermal fish species, brown trout (Salmo trutta L.) in order to allow for a holistic evaluation of the potential effects of temperature. Five temperatures (4°C, 6°C, 8°C, 10°C, and 12°C) were tested, and the effects of temperature were analyzed at three stages: hatching, emergence, and first food intake. A mean of 5,440 (S.E. ± 573) eggs, coming from seven females and seven males (seven families) captured close to Linkebeek (Belgium), were used for each temperature. Maximum survival of well-formed fry at first food intake and better use of energy budget were found at 6°C and 8°C, temperatures at which the possible contribution to the next generation should therefore be greatest. At 12°C, the experimental population fell dramatically (0.9% survival rate for well-formed fry at first food intake), and fry had almost no yolk sac at first food intake. The present results on survival at 12°C are in accordance with predictions of a sharp decrease in brown trout numbers in France over the coming decades according to climate change projections (1°C to 5°C temperature rise by 2100 for France). At 10°C, there was also a lower survival rate (55.4% at first food intake). At 4°C, the survival rate was high (76.4% at first food intake), but the deformity rate was much higher (22% at first food intake) than at 6°C, 8°C, and 10°C. The energetic budget showed that at the two extreme temperatures (4°C and 12°C) there was less energy left in the yolk sac at first food intake, suggesting a limited ability to survive starvation.
... After hatching, fry feed on the yolk sac and when the yolk reserves decrease, they leave the gravel and enter into the water column , a phenomenon known as " emergence, " which occurs at approximately 65 6 19 days post hatching (dph) at 8 C (Teletchea et al. 2009). Under natural conditions, emergence is followed by the dispersal of the fry (Gaudin and Héland 1995; Héland et al. 1995) and depends on the local abiotic conditions such as warming water temperature (Cô té and Green 2012). It is well known that this phenomenon depends on fry development, and is strongly affected by temperature, but nothing is known about the social changes occurring during emergence. ...
Article
Full-text available
A host of abiotic factors modify fish social behaviour. However, few studies have characterised the effects of temperature on behaviour. In this study, brown trout Salmo trutta fry were reared at five different temperatures (4, 6, 8, 10 and 12°C). In order to characterise group structure, three behavioural parameters were investigated: group social structure (based on inter-individual distances), inter-individual relationships (based on physical contacts) and individual activity. These behavioural parameters were studied at the emergence stage, which corresponds to a switch from a social gregarious life in the gravel to a solitary one in the water column. Data analysis showed that the inter-individual distances increased with increasing temperature, particularly the nearest neighbour distance. The mean number of physical contacts between fry increased at both low and high temperatures. At high temperatures, most fry moved apart from each other after a physical contact. Swimming activity decreased at both the lower and upper temperatures (18 % of activity at 4°C, 38 % at 8°C and 12 % at 12°C). This study showed that temperature modifies brown trout fry activity, inter-individual relationships and social behaviour, which all affect group cohesion before emergence and can influence their survival and dispersal.
... Ils s'éloignent des berges en cours de journée pour défendre de petits territoires (≈ 0.1-0.2 m 2 , Grant et al., 1998) et se nourrir d'organismes entrainés par le courant (Gaudin et al., 1995). Ils rejoignent les rives pendant la nuit, qui constituent des sites de repos et de protection vis-à-vis des prédateurs . ...
Article
Full-text available
Stream-dwelling salmonids are territorial; from early-life stages they undergo intense competition for habitat and food. These interactions may affect mortality, migration and growth, at variable intensities in function of ontogeny and environmental factors. In Switzerland, brown trout Salmo trutta L. is the most favoured species by anglers. Most of the populations are subjected to the stocking of juveniles, released during their first summer ("summerlings"). The rearing in hatcheries of these individuals, which are the progeny of captive broodstock, can have deleterious effects on the genetic diversity as well as on the fitness of the introduced fish. In addition, these individuals are bound to affect the wild population dynamics. Some behaviours (aggression and predator avoidance) have already been studied under controlled conditions, but the consequences have rarely been measured in a natural environment. This thesis aims to evaluate the intensity of the biotic, i.e. density-dependant, mechanisms between wild and stocked trout through a series of experiments in various rivers. The biotic interactions at the juvenile stage were first described in a natural resident population. Thereafter a series of experiments were carried out in controlled and natural environments to evaluate the efficiency and limitations of two marking techniques suitable for young trout: an externally detectable fluorescent marker (calcein) and an individual marking by implantation of a PIT tag. Both techniques were used to evaluate the effects of density and size of the stocked fish on the wild juveniles, through in situ investigations in three contrasted rivers. Finally the results of the various marking-recapture experiments were used to model the apparent mortality of stocked versus wild fish, and to find which environmental factors explain the observed variability. The results show the importance of the density-dependant regulation on the apparent survival, i.e. rate of change, and the size of wild fish, as well as the interactions between fish density and environmental factors, especially water flow. In rivers subjected to stocking, survival is usually much greater for wild than for introduced fish, except in one of the rivers with low slope. Increasing the stocked density does not influence directly the survival of both stocked and wild fish, but can increase the downstream movement of individuals of both origins. By combining capture-recapture data collected from seven streams in this study, results show an increase of the initial apparent mortality (within a few days post-stocking) of stocked juveniles with increasing stocked density and stream width. The morphological characteristics of the rivers also affect the delayed over-mortality of the stocked fish. These results must be corroborated through supplementary marking-recapture experiments coupled with detailed environmental records.
... Pour déterminer l'influence de ces fluctuations artificielles de débit, souvent jugées responsables d'impacts négatifs sur la faune aquatique (CUSHMAN, 1985 ;LAUTERS, 1992 ;CEREGHINO, 1997et al., 1994b), n'ont pas montré, lors de simulations d'éclusées, d'augmentation significative de la dérive d'alevins d'ombre âgés de 2 mois, alors que les effets sur des alevins de truite du même âge apparaissaient modérés (VALENTIN, 1995). D'autres travaux, sur la distribution spatiale et la survie dès l'émergence des alevins de diverses espèces de salmonidés, ont montré la fragilité des alevins émergents dans leur nouveau milieu (ELLIOTT, 1989 ;BARDONNET et al., 1993 ;GAUDIN et HELAND, 1995 ;HELAND et al., 1995), en particulier face aux variations de débit (OTTAWAY et CLARKE, 1981 ;IRVINE, 1986 ;HEGGENES et TRAAEN, 1988). A partir de ces informations, il est apparu nécessaire d'une part de vérifier dans un cadre expérimental cohérent que les éclusées provoquent bien une dérive des alevins post-émergents de truite commune, et d'autre part de quantifier cet impact. ...
Article
Le fonctionnement par éclusées de certains ouvrages hydroélectriques installés sur des rivières de montagne à peuplement salmonicole est souvent considéré comme responsable du déficit en alevins observé sur les secteurs à l'aval immédiat du rejet. Une des causes majeures avancée de ce déficit est l'entraînement forcé des alevins dès l'émergence. Une approche expérimentale de ce phénomène est apparue nécessaire pour identifier et quantifier les facteurs mis en jeu. Un ancien bras de la rivière Oriège a été ainsi aménagé au niveau du canal de fuite de l'usine hydroélectrique d'Orlu, en Ariège (09). Ce système semi-naturel permet, sur un substrat et des abris naturels, de simuler des éclusées et de quantifier la dérive des alevins résultante. Sur un bief à faciès d'écoulement mixte radier-plat, nous avons testé deux modalités pour la durée des éclusées (10 minutes et 3 heures), associées à deux modalités pour la valeur du débit de base (débit précédant l'éclusée), soit 150 et 250 l/s. Le débit plafond des éclusées a été fixé à 1 500 l/s, ce qui correspond à un facteur de 6 à 10 par rapport aux débits de base, situation fréquemment rencontrée sur l'Oriège. Les résultats sont comparés et discutés. En définitive, il apparaît que les éclusées entraînent systématiquement une dérive forcée des alevins. Cette dérive intervient principalement au démarrage de l'éclusée et est d'autant plus forte que le débit de base est faible.
Thesis
Full-text available
It is an ongoing issue to better understand colonization process, adaptation potential to new environments, and invasiveness of a species. The sub Antarctic Kerguelen Islands are a perfect model to model population dynamics in an invasion context, because it represents a simplified case of invasion by brown trout (Salmo trutta L.), a facultative anadromous fish. Introduced in the 1950s, and thanks to its dispersive and adaptive capacities, the brown trout provides a unique study model for understanding the causes and mechanisms underlying biological invasions. Understanding dispersal mechanisms, through the study of life history traits related to migration (e.g. growth, age at migration) and their temporal evolution in shifting expansion range population, is the core of this thesis work. Through the study of scales collected in this unique framework, the life histories of nearly 5000 fish have been rebuilt. This work demonstrates the importance of the methodology to determine accurate estimates of individual life history traits. Modelling the evolution of freshwater growth, body size at age and age at first migration demonstrates that evolutionary processes are at work according to the time since colonization. In particular, the decrease in growth rate over time and the decrease in body size at age over time and space suggest that the dispersal capacity is decreasing in populations located at the margins. The evolution of the threshold size at first migration confirms this results, and illustrates the importance of phenotypic plasticity and local adaptation in the choice of migratory tactics. However, the approach taken in this manuscript focuses on the evolution of migration, and would benefit from the study of the joint evolution of traits involved in fitness (costs-benefits balance), such as reproduction, or growth at sea.
Chapter
The first studies of salmonid population dynamics have shown the determining role of behavioural factors, particularly competition for space and food in the limiting of natural populations and their distribution (Allen, 1969; McFadden, 1969; Le Cren, 1973). This role of behaviour and competition in the biology of populations and its consequences on fish production appears to be especially marked for the brown trout, Salmo trutta L., a strongly territorial salmonid species in freshwater lotic environments (Onodera, 1967; Noakes, 1978, Thorpe, 1982).
Chapter
Within its overall area of distribution, the brown trout (Salmo trutta L.) is not always present, nor is it evenly distributed in the water courses. Among the factors regulating natural populations of trout, environmental conditions are of great importance and allow the definition of the habitat of this species.
Article
The diel timing of displacement of emerging brown trout (Salmo trutta) was studied by trapping the alevins at the downstream end of three experimental channels. The presence of phosphorescent landmarks on the substrate delayed the catches during the first hours of complete darkness, but increased them during twilight. During daylight, the presence of the landmarks was associated with greatly increased numbers of free-swimming fishes.