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We combined habitat mapping, radio tracking of adults, redd mapping, and genetic parentage analysis on juveniles for 2 consecutive years to test eight predictions on the reproductive payoffs and individual features associated with space use tactics of anadromous Atlantic salmon (Salmo salar) in a natural population. Regarding payoffs, we found that (1) males settled in better habitat, visited more redds, and tended to get more mates than males settled in poorer habitat; (2) they also sired more offspring; (3) the latter effect was stronger in the first year, when redds were more aggregated; and (4) female reproductive success increased with habitat quality in their home range, especially in the first year. For individual features, (5) individuals that settled earlier in their home range had better habitat for juvenile production, but only in the first year; (6) females were less mobile than males, especially in the second year; (7) larger males did not settle in better habitats than smaller males; and (8) smaller males were not more mobile than larger males. Nous combinames la cartographie de l'habitat et des frayeres, le suivi radio des geniteurs et l'analyse de parente sur les alevins pendant deux annees pour tester huit predictions sur les gains et les caracteristiques individuelles associes aux tactiques spatiales dans une population de saumons de l'Atlantique (Salmo salar). Concernant les gains, nous trouvames que (1) les males etablis dans les meilleurs habitats visiterent plus de frayeres et eurent plus de partenaires; (2) ils engendrerent plus de descendance; (3) ce dernier effet fut plus marque quand les frayeres etaient plus agregees; et (4) le succes reproducteur des femelles augmentat avec la qualite d'habitat dans leur domaine vital, surtout lors de la premiere annee. Pour les caracteristiques individuelles, (5) les individus s'etablissant en premier dans leur domaine vital occuperent un habitat plus favorable pour la production de juveniles; (6) les femelles furent moins mobiles que les males, surtout lors de la deuxieme annee; (7) les plus grands males ne s'etablirent pas dans de meilleurs habitats que les petits; et (8) qui ne furent pas plus mobiles que les grands., Introduction The spatiotemporal distribution of resources imposes a selective pressure on many aspects of individual behavior: where to settle (Fretwell and Lucas 1969), how long to stay in a given [...]

We investigated the use of Sr:Ca, Ba:Ca, and [sup.87]Sr: [sup.86]Sr ratios as natural tags for determining the natal origins of juvenile and adult Atlantic salmon (Salmo salar) from 12 tributaries in the Adour basin (southwestern France) and estimated homing on a tributary scale. Geochemical signatures from core regions of the otolith were also used to identify fish from hatchery or naturally spawned sources. Quadratic discriminant function analysis (QDFA) was on average 80% successful at classifying juveniles according to their natal rivers. Adults of unknown natal origin were assigned to their natal rivers using the juvenile fingerprints from QDFA approach. Only 18 adults originated from streams not included in the juvenile database. Although most of the adults showed a marked homing instinct, homing was not perfect, and some wild fish strayed into non-natal spawning areas. Returns of hatchery-reared fish as adult spawners represented 10% of the total sampled fish. Allocation of fish to natal tributaries or hatcheries illustrated the abundance and relative contributions of natal sources, important for the recovery of Atlantic salmon in this area. Nous nous sommes penches sur l'utilisation des rapports Sr:Ca, Ba:Ca et [sup.87]Sr: [sup.86]Sr comme marqueurs naturels des origines natales de saumons atlantiques juveniles et adultes provenant de 12 affluents du bassin de l'Adour (sud-ouest de la France) et avons estime le retour a l'echelle des affluents. Les signatures geochimiques des regions centrales d'otolithes ont egalement ete utilisees pour distinguer les poissons issus d'ecloseries de ceux issus du frai en milieu naturel. Le taux de succes moyen de l'analyse discriminante quadratique (QDFA) pour ce qui est de classer les juveniles selon leurs rivieres natales etait de 80 %. La determination de la riviere natale des adultes d'origine natale inconnue reposait sur les empreintes de juveniles tirees de la QDFA. Seuls 18 adultes provenaient de cours d'eau ne figurant pas dans la base de donnees des juveniles. Bien que la plupart des adultes presentaient un instinct de retour marque, le retour n'etait pas parfait, certains poissons sauvages se retrouvant dans des regions de frai non natales. Les poissons eleves en ecloserie retournant comme geniteurs adultes representaient 10 % du total des poissons echantillonnes. La repartition des poissons entre affluents natals et ecloseries illustre l'abondance et les contributions relatives des sources natales, qui jouent un role important dans le retablissement du saumon atlantique dans la region. [Traduit par la Redaction], Introduction Identifying the natal origins of Atlantic salmon is one of the most attractive aspects of understanding the population structure of this highly migratory fish. Such information is beneficial to [...]

During the reproductive season, animals have to manage both their energetic budget and gamete stock. In particular, for semelparous capital breeders with determinate fecundity and no parental care other than gametic investment, the depletion of energetic stock must match the depletion of gametic stock, so that individuals get exhausted just after their last egg is laid and fertilized. Although these budgets are managed continuously, monitoring the dynamics of mating acts and energy expenditure at a fine temporal scale in the wild is challenging. This study aimed to quantify the individual dynamics of spawning acts and the concomitant energy expenditure of female Allis shad (Alosa alosa) throughout their mating season. Using eight individual-borne accelerometers for one month, we collected tri-axial acceleration, temperature, and pressure data that we analysed to i) detect the timing of spawning acts, ii) estimate energy expenditure from tail beat frequency and water temperature, and iii) monitor changes in body roundness from the position of the dorsally-mounted tag relative to the vertical plane. Female shad had a higher probability to spawn during warmer nights, and their spawning acts were synchronized (both individually and inter-individually) within each active night. They experienced warmer temperature, remained deeper, swan more slowly and spent less energy during daytime than night time. Over one month of spawning, they performed on average 15.75 spawning acts, spent on average 6 277 kJ and died with a significant portion of residual oocytes. The acceleration-based indicator of body roundness was correlated to condition coefficient measured at capture, and globally decreased through the spawning season, although the indicator was noisy and was not correlated to changes in estimated energy expenditure. Despite significant individual variability, our results indicate that female shad exhausted their energetic stock faster than their egg stock. Water warming will increase the rate of energy expenditure, which might increase the risk that shad die with a large stock of unspent eggs. Although perfectible, the three complementary analyses of acceleration data are promising for in situ monitoring of energy expenditure related to specific behaviour.

We present a multiwavelength, multichannel, time-domain near-infrared spectroscopy system named MAESTROS. This instrument can measure absorption and scattering coefficients and can quantify the concentrations of oxy- and deoxy-haemoglobin ([HbO 2 ], [HHb]), and oxidation state of cytochrome-c-oxidase ([oxCCO]). This system is composed of a supercontinuum laser source coupled with two acousto-optic tuneable filters. The light is collected by four photomultipliers tubes, connected to a router to redirect the signal to a single time-correlated single-photon counting card. The interface between the system and the tissue is based on optical fibres. This arrangement allows us to resolve up to 16 wavelengths, within the range of 650-900 nm, at a sampling rate compatible with the physiology (from 0.5 to 2 Hz). In this paper, we describe the system and assess its performance based on two specifically designed protocols for photon migration instruments, the basic instrument protocol and nEUROPt protocols, and on a well characterized liquid phantom based on Intralipid and water. Then, the ability to resolve [HbO 2 ], [HHb], and [oxCCO] is demonstrated on a homogeneous liquid phantom, based on blood for [HbO 2 ], [HHb], and yeast for [oxCCO]. In the future, the system could be used to monitor brain tissue physiology.