Time filter

Source Type

Québec, Canada

Roy M.L.,University of Montreal | Roy A.G.,University of Montreal | Grant J.W.A.,Concordia University at Montreal | Bergeron N.E.,INRS Eau
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2013

The magnitude of variation of diel activity patterns and habitat use of wild Atlantic salmon (Salmo salar) parr was examined during the summer and autumn through a gradient of declining temperature. Fish were marked with passive integrated transponders and tracked using a large network of flatbed antennas. High interindividual variability was observed, as some individuals were predominantly nocturnal whereas others frequently changed their daily activity pattern. Overall fish activity decreased with decreasing temperature and increasing flow stage, but most of these changes in daily activity were observed in crepuscular periods. Parr used habitats with lower velocity at night than in the day during the summer, but not in the autumn. Furthermore, there was no difference between day and night habitats for fish that were cathemeral (active both day and night during a given day), so differences between day and night habitats were the result of individuals adopting different activity patterns. These results suggest that habitat interacts with activity pattern, as individuals using suboptimal habitats seem to increase daytime foraging to secure sufficient energy. Temporal and among-fish variability of activity patterns illustrate the dynamic nature of foraging decisions that may partly result from trade-offs experienced at the microhabitat scale. Source

Roy M.L.,University of Montreal | Roy A.G.,University of Montreal | Grant J.W.A.,Concordia University at Montreal | Bergeron N.E.,INRS Eau
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2013

Stream-dwelling salmonid populations are generally thought to be composed of both relatively mobile and sedentary individuals, but this conclusion is primarily based on results obtained from recapture methods with low temporal resolution. In this study, the mobility of 50 juvenile Atlantic salmon (Salmo salar) was monitored using a large array of passive integrated transponder antennas buried in the bed of a natural stream. Fish locations were recorded at a high frequency for a period of 3 months in a 65mreach. Four types of daily behaviour were identified: stationary (detected primarily at one location), sedentary (limited movement between a few locations), floater (frequent movements in a restricted home range), and wanderer (movements across the reach). Most individuals exhibited low mobility on most days, but also showed occasional bouts of high mobility. Between-individual variability accounted for only 12%-17% of the variability in the mobility data. High mobility was more frequent at low flow, but no difference was observed between the summer (12-18 °C) and the autumn (4-12 °C). Individual variation on a daily basis suggested that movement behaviour is a response to changing environmental conditions rather than an individual behavioural trait. Source

Mailhot A.,INRS Eau | Lachance-Cloutier S.,Center dexpertise hydrique du Quebec | Talbot G.,INRS Eau | Favre A.-C.,Polytechnic School of Algiers
Journal of Hydrology | Year: 2013

The Peak-Over-Threshold (POT) approach is an interesting alternative to the one based on Annual Maxima (AM) series since it gives the opportunity to take into consideration extreme events that would not be considered otherwise. It has also been recognized that the regional approach improves statistical inference when compared to the local approach, assuming that the region is statistically homogeneous. A regional POT approach was developed and applied to the network stations located in southern Québec. POT series for 5-, 10-, 15-, 30-min and 1-, 2-, 6- and 12-h durations were constructed assuming a fixed exceedance rate. An analysis of local POT series showed that the intra-annual variability of the Generalized Pareto Distribution (GPD) parameters needs to be taken into consideration. Models of various complexities were defined combining local and regional representations as well as the intra-annual variability of GPD parameters. Regional likelihood was estimated and models were compared based on the Akaike Information Criterion (AIC). Models with regional shape and scale parameters and accounting for intra-annual variability were selected for all durations. Spatial covariates were also introduced through a simple model linking GPD parameters to latitude, longitude and altitude. The sensitivity of results to threshold values and selected models was also investigated. Interpolated maps of intense rainfall over the studied area are finally proposed. © 2012 Elsevier B.V. Source

This study compares, for the southern region of Quebec (Canada), different estimators of intensity- duration-frequency (IDF) curves based on the partial duration series (SDP) or series of annual maxima (SMA). Two models were considered for the SMA, the first one with one local parameter (SMA-1), and the second with two local parameters (SMA-2). For the SDP, the series were built defining, in one case, a regional threshold (SDP-1), and in the other case, the regional average number of threshold exceedences (SDP-2). The quantiles of these models and their 90% error bounds were estimated and compared. The SDP-1 model was finally selected because, according to the literature, it would suit a region like that under study which displays reasonable heterogeneity. Furthermore, the SDP-1 model fits the empirical quantiles and probabilities relatively well. At each site, quantiles estimated by this regional model are compared to those obtained using the local SDP model. © 2010 IAHS Press. Source

Johnston P.,INRS Eau | Bergeron N. E.,INRS Eau
Ecology of Freshwater Fish | Year: 2010

Abstract - The objective of this study was to determine the proximate body composition of juvenile Atlantic salmon along the sequence of aquatic habitat types created by longitudinal changes in the riverbed substrate of two rivers (i.e., sedimentary links units). Interesting trends in the body composition were observed but our initial hypothesis, that fish of the upstream sections have higher energy content, was nevertheless not verified. No common longitudinal pattern was detected in the body composition (water, lipid, energy density) along the studied rivers. Trends in the body constituents were different between age-classes and rivers, whereas they were highly variable within- and among-samples. There was however a common trend in the pattern of variations, with the coefficient of variations increasing in the downstream direction for almost all constituents, age-classes and rivers. Potential abiotic and biotic factors that might have contributed to these observations are discussed. © 2010 John Wiley & Sons A/S. Source

Discover hidden collaborations