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The paper presents the results of laboratory triaxial compression tests to study the stiffness of very loose Fraser River sands. The stiffness has been shown to be very dependent on the time of confinement prior to shearing and the stress ratio at which the sample is aged. Higher stress ratios resulted in very low initial moduli with no ageing, but the moduli increased by several hundred percent during the first 1000 min of ageing. For ageing at a stress ratio of 1.0 (i.e., isotropic ageing), the initial moduli were higher than those for ageing at high stress ratios, but the stiffness increased by only about 60% during the first 1000 min of ageing. The rate of stiffness increase was approximately linear with the logarithm of time up to ageing times of 10 000 min (>1 week). Ageing at any stress ratio resulted in reduced contractive volumetric strain during subsequent shearing, reflecting a change in soil structure during ageing. The dℇ[sub v] /dℇ[sub a] ratio under triaxial compression loading decreased as the ageing stress ratio increased. The results suggest that close attention must be paid to the age of laboratory samples prepared to study the stress–strain response of sands at strains up to about 0.1%, particularly in studies on loose sand.Key words: sands, ageing, creep, modulus.Cet article présente les résultats d'un programme d'essais en laboratoire pour étudier la rigidité de sables très lâches du fleuve Fraser au moyen d'essais de compression triaxiale. On a montré que la rigidité était très dépendante du temps de confinement antérieur au cisaillement et du rapport des contraintes sous lequel l'échantillon a vieilli. Des rapports de contraintes plus élevés ont donné des modules initiaux très faibles sans vieillissement, mais les modules ont augmenté de plusieurs 100 % au cours des mille premières minutes de vieillissement. Sous un vieillissement isotrope, les modules initiaux étaient plus élevés que pour des rapports de contraintes plus élevés mais la rigidité a augmenté de seulement environ 60 % durant les 1000 premières minutes de vieillissement. La vitesse d'augmentation de la rigidité était approximativement linéaire en fonction du logarithme du temps jusqu'à des temps de vieillissement de 10 000 minutes (>1 semaine). Le vieillissement sous n'importe quel rapport de contraintes a donné des déformations volumétriques de contraction réduites durant le cisaillement subséquent, ce qui indiquait un changement dans la structure du sol durant le vieillissement. Le rapport dℇ[sub v] /dℇ[sub a] sous chargement triaxial en compression a diminué lorsque le rapport de contraintes de vieillissement augmentait. Les résultats suggèrent que l'on doit porter un attention particulière à l'âge des échantillons préparés en laboratoire pour étudier la réponse contrainte-déformation des sables jusqu'à des déformations de 0,1 %, particulièrement dans les études sur le sable lâche.Mots clés : sables, vieillissement, fluage, module.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Fraser River sockeye salmon have been the basis for a major commercial fishery shared by Canada and the United States, and an important cultural foundation for many aboriginal groups; they are also of huge ecological significance throughout the Fraser Basin. The potential for altered aquatic habitat and temperature regimes due to climate change is an important concern for Fraser River sockeye salmon. This paper characterizes the vulnerability of Fraser River sockeye salmon to future climate change using an approach that is novel on three counts. First, previous efforts to assess the vulnerability of salmon to climate change have largely focused on only part of the life cycle, whereas we consider climate vulnerability at all stages in the life cycle. Second, we use the available scientific literature to provide a basis for structuring and eliciting judgments from fisheries science and management experts who research and manage these systems. Third, we consider prospects for mitigating the effects of climate change on sockeye salmon. Tests showed that participants’ judgments differentiated in statistically significant ways among questions that varied in terms of life stages, spawning regions and climate scenarios. The consensus among participants was that Fraser River sockeye are most vulnerable to climate change during the egg and returning adult stages of the life cycle. A high temperature scenario was seen as imposing the greatest risk on sockeye stocks, particularly those that migrate to the upper reaches of the Fraser River system and spawn earlier in the summer. The inability to alter water temperature and the highly constrained nature of sockeye management, with competing gear types and sequential fisheries over a long distance, suggest the potential to mitigate adverse effects is limited. Fraser River sockeye already demonstrate a great deal of adaptive capacity in utilizing heterogeneous habitats in different river sub-basins. This adaptability points to the potential value of policies to make stocks more resilient to uncertain futures. [Copyright &y& Elsevier]

This paper summarizes the results of six seasons of archaeological fieldwork conducted at the Scowlitz site located at the confluence of the Harrison and Fraser Rivers in SW British Columbia, Canada. Research beginning in 1992 has revealed a complex sequence of site use beginning with a residential occupation about 3000 years ago. After some 1500 years the site became a cemetery, featuring some of the best preserved examples of the burial mound and cairn complex remaining on the Northwest Coast. Then, 1000 years ago, the site added seasonal use for resource processing while continuing as a cemetery. In the protohistoric and historical periods the site was used as a fishing camp and, still, as a cemetery. We discuss the implications of the Scowlitz site for understanding the development of complex hunting-fishing-gathering societies on the Northwest Coast. [ABSTRACT FROM AUTHOR]

Presents the findings of a study on the estuarine water quality management for the Lower Fraser River in British Columbia. Overview of the methodological procedures for data collection and analysis; Information on the number and types of coordinative arrangements between organizations; Background on the procedures for implementing coordinative arrangements, including referrals.

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This article proposes a hierarchical multivariate conditional autoregressive model applied to a compositional response vector. We particularly focus on situations when the composition is discrete occurring when observations are based on small multinomial counts. We address drawbacks that exist in current modeling approaches for such data. Our hierarchical model will be demonstrated with data used to help manage a commercial sockeye salmon fishery in the Fraser River of British Columbia. [ABSTRACT FROM AUTHOR]

The article focuses on the biological features of Fraser River sockeye salmon after their postsmolting year in British Columbia. It mentions that the postsmolting period is a 12-month period wherein the fish searches for food at the same time avoiding predation and fish diseases in the Northeast Pacific. It also discusses the distribution and migration of the sockeye salmon during the said period.

Evolutionary adaptation affects demographic resilience to climate change but few studies have attempted to project changes in selective pressures or quantify impacts of trait responses on population dynamics and extinction risk. We used a novel individual-based model to explore potential evolutionary changes in migration timing and the consequences for population persistence in sockeye salmon Oncorhynchus nerka in the Fraser River, Canada, under scenarios of future climate warming. Adult sockeye salmon are highly sensitive to increases in water temperature during their arduous upriver migration, raising concerns about the fate of these ecologically, culturally, and commercially important fish in a warmer future. Our results suggest that evolution of upriver migration timing could allow these salmon to avoid increasingly frequent stressful temperatures, with the odds of population persistence increasing in proportion to the trait heritability and phenotypic variance. With a simulated 2&degree;C increase in average summer river temperatures by 2100, adult migration timing from the ocean to the river advanced by ∼10 days when the heritability was 0.5, while the risk of quasi-extinction was only 17% of that faced by populations with zero evolutionary potential (i.e., heritability fixed at zero). The rates of evolution required to maintain persistence under simulated scenarios of moderate to rapid warming are plausible based on estimated heritabilities and rates of microevolution of timing traits in salmon and related species, although further empirical work is required to assess potential genetic and ecophysiological constraints on phenological adaptation. These results highlight the benefits to salmon management of maintaining evolutionary potential within populations, in addition to conserving key habitats and minimizing additional stressors where possible, as a means to build resilience to ongoing climate change. More generally, they demonstrate the importance and feasibility of considering evolutionary processes, in addition to ecology and demography, when projecting population responses to environmental change. [ABSTRACT FROM AUTHOR]

The mortality of salmon smolts during their migration out of freshwater and into the ocean has been difficult to measure. In the Columbia River, which has an extensive network of hydroelectric dams, the decline in abundance of adult salmon returning from the ocean since the late 1970s has been ascribed in large measure to the presence of the dams, although the completion of the hydropower system occurred at the same time as large-scale shifts in ocean climate, as measured by climate indices such as the Pacific Decadal Oscillation. We measured the survival of salmon smolts during their migration to sea using elements of the large-scale acoustic telemetry system, the Pacific Ocean Shelf Tracking (POST) array. Survival measurements using acoustic tags were comparable to those obtained independently using the Passive Integrated Transponder (PIT) tag system, which is operational at Columbia and Snake River dams. Because the technology underlying the POST array works in both freshwater and the ocean, it is therefore possible to extend the measurement of survival to large rivers lacking dams, such as the Fraser, and to also extend the measurement of survival to the lower Columbia River and estuary, where there are no dams. Of particular note, survival during the downstream migration of at least some endangered Columbia and Snake River Chinook and steelhead stocks appears to be as high or higher than that of the same species migrating out of the Fraser River in Canada, which lacks dams. Equally surprising, smolt survival during migration through the hydrosystem, when scaled by either the time or distance migrated, is higher than in the lower Columbia River and estuary where dams are absent. Our results raise important questions regarding the factors that are preventing the recovery of salmon stocks in the Columbia and the future health of stocks in the Fraser River. [ABSTRACT FROM AUTHOR]

Presents a study that examined the dunes and associated sand transport in a tidally influenced sand-bed channel in Fraser River, British Columbia. Methodology; Flow conditions and bed-form geometry; Dune migration and transport.

The Fraser River valley near Clinton contains a thick sediment fill that is presently incised down to bedrock. The sequence, approximately 500 m thick, is generally upward fining and consists of up to 100 m of glacigenic debris flow diamicton and glaciofluvial–deltaic gravel and sand at the base, overlain by about 350 m of glaciolacustrine sediments and minor diamicton, which is in turn capped by several metres of till. The sequence is interpreted to represent (i) valley aggradation in response to glaciation, followed by (ii) the impoundment of the valley by sediment and (or) ice, and the formation of a large proglacial lake(s), and finally (iii) overriding of the valley fill by glaciers. This glacial advance sequence can be readily correlated with previously studied units situated immediately to the north, most of which have been associated with the last glaciation; however, the age of these units has been based only on stratigraphic relations. We introduce limiting optical ages from a widespread glaciolacustrine unit that show that the glacial advance sequence was formed, at the earliest, during the penultimate Okanagan Centre Glaciation (oxygen isotope stage 4; ca. 74–59 ka), but almost certainly during the (last) Fraser Glaciation (oxygen isotope stage 2; ca. 24–12 ka). It could not have been deposited during oxygen isotope stage 6, or during an older glaciation.Près de Clinton, la vallée de la rivière Fraser est remplie d'épais sédiments qui sont présentement recoupés jusqu'au roc. La séquence, d'une épaisseur d'environ 500 m, est à affinement vers le haut et comprend jusqu'à 100 m de diamicton provenant d'écoulements de débris glaciogéniques et de sable et de gravier fluvio-glaciaire–deltaïque à la base, recouvert d'environ 350 m de sédiments glacio-lacustres et de diamictons mineurs qui sont à leur tour recouverts de plusieurs mètres de till. Selon notre interprétation, la séquence représente (i) l'accumulation dans la vallée, résultat de la glaciation, suivie (ii) du barrage de la vallée par les sédiments et (ou) de la glace et la formation d'un ou de plusieurs grands lacs glaciaires et finalement, (iii) une avancée glaciaire qui recouvre tout dans la vallée. Cette séquence d'avancée glaciaire peut être corrélée aisément à des unités localisées immédiatement au nord étudiées antérieurement. La plupart de ces unités ont été associées à la dernière glaciation; toutefois, l'âge de ces unités a seulement été basé sur des relations stratigraphiques. Nous introduisons des âges optiques limites provenant d'une unité glacio-lacustre de grande portée qui montre que la séquence d'avancée glaciaire a été formée, au plus tôt, au cours de l'avant-dernière glaciation de l'Okanagan-Centre (étape 4, isotope de l'oxygène; ca. 74–59 ka) mais presque assurément au cours de la (dernière) glaciation Fraser (étape 2, isotope de l'oxygène; ca. 24–12 ka). La séquence ne pourrait pas avoir été déposée durant l'étape 6 de l'isotope de l'oxygène, ni durant une glaciation antérieure.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

As part of a project to evaluate a side-looking, split-beam acoustic system for enumerating migrating salmon in the Fraser River in British Columbia, Canada, a stochastic model is being developed to estimate the numbers of fish migrating upstream past the acoustic site. The model exploits the unique ability of a split-beam system to measure the three-dimensional position of resolved point source targets and to track the target trajectories through the beam. The problem of non-uniform detection probability combined with non-uniform fish density over the beam cross-section is addressed by the model. The model estimates the number of migrating salmon using the observed echo distribution, the trajectories of tracked fish, and the detection probability. [ABSTRACT FROM PUBLISHER]

The article discusses the study by D. Welch and colleagues on the survival of migrating salmon smolts in rivers with and without dams. The authors of the study used the Pacific Ocean Shelf Tracking (POST) array, an acoustic telemetry system to measure the effect of dams on survivals. The researchers compared the fate of Chinook and steelhead migrants leaving in Columbia-Snake River system with those in the unfettered Thompson-Fraser River system in south central British Columbia.