[1] Three-dimensional finite element models were established for the Newfoundland and Labrador Shelf to investigate climatological monthly mean wind-and density-driven circulation. The model was forced using wind stresses from the National Center for Environmental Prediction-National Center for Atmospheric Research reanalysis data prescribed at the sea surface, large-scale remote forcing determined from a North Atlantic model, monthly mean temperature and salinity climatology, and M 2 tide on the open boundary. The model results were examined against various in situ observations (moored current meter, tide gauge, and vessel-mounted acoustic Doppler current profiler data) and satellite drift measurements and discussed together with literature information. The seasonal mean circulation solutions were investigated in terms of relative importance of wind to density forcing for the Labrador Current. The model results indicate significant seasonal and spatial variations, consistent generally with previous study results and in approximate agreement with observations for the major currents. The region is dominated by the equatorward flowing Labrador Current along the shelf edge and along the Labrador and Newfoundland coasts. The Labrador Current is strong in the fall/winter and weak in the spring/summer. The mean transport of the shelf edge Labrador Current is 7.5 Sv at the Seal Island transect and 5.5 Sv through the Flemish Pass. The seasonal ranges are 4.5 and 5.2 Sv at the two sections, respectively. Density-and wind-driven components are both important in the inshore Labrador Current. The density-driven component dominates the mean component of the shelf edge Labrador Current while the large-scale wind-forcing contributes significantly to its seasonal variability.

We investigated the magnitude of short-term variations in the flux of several species of fish larvae in Conception Bay, Newfoundland, determined the contribution of these fluxes to changes in the abundance of these species, and assessed the factors that may be causing the variations in these fluxes. The net effect of transport ranged from a daily influx of 5.8% to a daily efflux of 6.2% from the population. Short-term variations in transport were associated with variations in wind stress. The contribution of transport to variations in population abundance ranged from 12 to more than 75% of the average daily rate of change in numbers for the different species. The contribution of physical processes to estimated mortality rates is variable and can have a significant impact on the investigation and interpretation of potential biological processes (e.g., predation and starvation) influencing the survival of larval fish. We predicted that the average correction to the instantaneous mortality rate due to advection and diffusion should be proportional to A−1/2, where A is the area of system under study. This highlights the susceptibility of small systems to estimation error of mortality rates caused by short-term variations in physical forcing.

We present the results of a study designed to ascertain the importance of variations in transport of cod eggs and larvae on the northeast Newfoundland Shelf. The distribution of cod eggs and larvae is described from a series of ichthyoplankton surveys. The mean and variance in surface currents were estimated from five experiments in which clusters of drogued satellite-tracked drifters were released at the presumed northern limit of the stock's range. These data were used to project the patterns of drift both backward and forward in time and thus the possible sources and destinations of eggs and larvae. Considering the development from the youngest (stage I) to the oldest stages (larvae), we saw a north-to-south and an offshore-to-inshore progression in spatial patterns of spawning and a continuing increase in the overall level of dispersion with increasing age of offspring. The data do not support the hypothesis that coastal or offshore areas represent simple sources or sinks of cod eggs and larvae. Transport plays an important but highly variable role that is coupled to the spawning distribution of adult fish and the availability of suitable conditions or habitats when the young begin to undergo metamorphosis and settle.Résumé : Nous présentons les résultats d'une étude visant à établir l'importance des variations dans le transport des oeufs et des larves de morue sur la partie nord-est du plateau de Terre-Neuve. La distribution des oeufs et des larves est décrite à partir d'une série de relevés de l'ichtyoplancton. La moyenne et la variance des courants superficiels ont été estimées à partir de cinq expériences au cours desquelles des grappes de dériveurs à ancre flottante pistés par satellite ont été mises à l'eau à la limite nord présumée de l'aire du stock. Ces données ont servi à projeter les schémas de dérive de façon rétrospective et prospective, et donc les sources et destinations possibles des oeufs et des larves. En considérant le développement du stade le plus jeune (stade I) au stade le plus vieux (larves), nous avons observé une progression du nord vers le sud et du large vers les côtes dans les schémas spatiaux de la fraye, et une croissance continue du niveau global de dispersion à mesure que la progéniture avançait en âge. Les données ne confirment pas l'hypothèse selon laquelle les zones côtières ou hauturières représenteraient de simples sources ou puits pour les oeufs et les larves de morue. Le transport joue un rôle important mais hautement variable, qui est couplé à la distribution des adultes géniteurs et à la disponibilité de conditions ou d'habitats appropriés au moment où les jeunes commencent à se métamorphoser et à s'installer sur le fond. [Traduit par la Rédaction]

This paper investigates possible linkages between the environment and year‐class success of Newfoundland/ Labrador cod. Aspects of the physical environment relevant to recruitment are reviewed and the current knowledge of the patterns of spawning and larval occurrence is summarized. A critical review of investigations aimed at correlating recruitment with climactic fluctuations is made and concludes that these studies have been largely fruitless. A series of numerical simulations of particle drift are presented to investigate the potential importance of storms and to try to identify nursery grounds. These simulations suggest that Labrador Shelf eggs and larvae are segregated from Grand Banks eggs and larvae. Favorable storm tracks appear to be required for significant numbers of eggs and larvae to reach the bays of Northeast Newfoundland.

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