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Capelin (Mallotus villosus) spawning in the St. Lawrence Estuary is concentrated in the Upper Estuary (UE). The northwest Gulf of St. Lawrence (NW GSL) was presented as the principal nursery for capelin originating from the estuary. In 2009 and 2010, we investigated the abundance, distribution, and size structure of capelin larvae in this system, and a particle tracking model was used to simulate larval dispersion. There was evidence of retention and larval growth in the Lower Estuary (LE), and older larvae were found in the LE by the end of summer. In October 2009, it was possible to link the cohorts of large larvae to emergence events in the UE in spring. Capelin larvae were more abundant or bigger (mean length) in the LE relative to the NW GSL in fall 2006, 2008, and 2009. We conclude that the LE is the habitat of a unit of the GSL capelin population composed of individuals that are retained in this region following hatching in the UE and that there is limited mixing with larvae originating in the NW GSL. Dans l'estuaire du Saint-Laurent, la fraie du capelan (Mallotus villosus) est concentree dans l'estuaire moyen. Le nord-ouest dugolfe du Saint-Laurent (N-O GSL) a ete presente comme l'aire principale de croissance des larves issues de l'estuaire. En 2009 et 2010, nous avons etudie l'abondance, la distribution et la structure de taille des larves de capelan dans ce systeme et un modele numerique a ete utilise afin de simuler la dispersion des larves. Il y a evidence de retention et croissance des larves dans l'estuaire maritime (EM) et des larves agees sont observees dans l'EM a la fin de l'ete. En octobre 2009, il a ete possible de relier les cohortes de grandes larves aux emergences dans l'estuaire moyen au printemps. Les larves de capelan etaient plus abondantes ou plus grandes (longueur moyenne) dans l'EM comparativement au N-O GSL en 2006, 2008 et 2009. Nous concluons que l'EM est l'habitat d'une unite de la population de capelan du GSL formee de larves retenues dans la region suivant l'emergence dans l'estuaire moyen et qu'il y a probablement peu de melange avec des larves provenant du N-O GSL., Introduction Throughout its distribution range, capelin (Mallotus villosus) is a key forage species in cold-water marine ecosystems. The species comprises large migratory populations responsible for the transfer of energy among [...]

The benthic settlement success of American lobster ( Homarus americanus) postlarvae is a key factor in population dynamics, with the temperature being a key factor. Given the spatial distribution of the species, its pelagic larvae probably encounter various thermal zones during development. Little information is available on the ability of lobster larvae to acclimate to temperature or if this ability varies among geographic areas. The main objectives of this study were to characterize (i) the settlement behavior of the postlarvae in relation to (a) temperature during larval development and (b) the geographic origin of the maternal parent and (ii) the behavioral response of postlarvae with different thermal histories in the presence/absence of a thermocline. Results did not support the hypothesis of thermal adaptation among local populations, as settlement behavior of postlarvae did not differ among females from different geographic regions. In contrast, larval survival and settlement behavior and postlarval energetic conditions varied with development temperature. Behavioral plasticity in the benthic settlement was observed in relation to temperature structure of the experimental water column. This study suggests that there may be links between development temperature and the natural variability in survival and settlement of American lobsters. Findings emphasize the need for an integrated approach in lobster recruitment studies with the inclusion of behavior in dispersion models. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated ichthyoplankton community structure in the northwest Gulf of St. Lawrence in Canada. Data from sampling surveys that were conduted in spring from 1985 to 1987 were compared by the authors with data from spring 2005 to 2007 to examine changes in ichtyoplankton. The main goal of the sampling methodology was to report on the spawning activity of the Atlantic cod in the northwest Gulf. It is suggested that the study offers relevant information on current biodiversity and productivity of the fish community in the area.

In 1995 and 1996, groups of female cod (Gadus morhua) of varying nutritional condition and maturing at different temperatures were used to investigate relationships between female condition, egg production, egg characteristics, and viability. Over the two years, egg samples from every batch spawned by 34 females were analyzed for egg diameter, dry mass, and energy content. In addition, 51 egg batches from 24 females (ca. 2 egg batches female−1 yr−1) were used to monitor development rate and hatching success. The weighted mean egg dry mass was positively correlated (p<0.05) to the females' pre-spawning condition in 1996. In 1995 this positive correlation was not observed for females at ∼2°C during maturation. For both years, the decline in the mean egg dry mass per batch throughout spawning was correlated (p<0.05) with the females' post-spawning energy reserves. However, no trend in the total egg dry mass per batch during the sequence of spawning was observed. Thus, the total energy investment per batch remained stable throughout spawning and was not influenced by the depletion of the females' energy reserves. In 1996, high hatching successes were observed only for egg batches from females in high pre-spawning condition. However, egg size and dry mass showed no correlation with survival rate or hatching success in either year. [ABSTRACT FROM PUBLISHER]