scholarly journals The influence of tidal streams on the pre-spawning movements of Atlantic herring, Clupea harengus L., in the St Lawrence estuary

2001 ◽  
Vol 58 (6) ◽  
pp. 1286-1298 ◽  
Author(s):  
K Lacoste
Keyword(s):  
Clupea Harengus ◽  
Atlantic Herring ◽  
Lawrence Estuary ◽  
Tidal Streams ◽  
St Lawrence Estuary

Séparation des populations de hareng de l'Atlantique (Clupea harengus harengus) de l'estuaire du Saint-Laurent et de la péninsule gaspésienne

1980 ◽  
Vol 37 (1) ◽  
pp. 66-71 ◽  
Author(s):  
G. Côté ◽  
P. Lamoureux ◽  
J. Boulva ◽  
G. Lacroix
Keyword(s):  
Clupea Harengus ◽  
Atlantic Herring ◽  
Morphometric Characteristics ◽  
Lawrence Estuary ◽  
Clupea Harengus Harengus ◽  
St Lawrence Estuary ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

Examination of morphometric and meristic characteristics of Atlantic herring (Clupea harengus harengus) caught during spawning along the Gaspé coast and the St. Lawrence Estuary lead to the conclusion of the existence of at least three herring populations in that area. The first one occurs in the St. Lawrence Estuary, spawns in the spring and is characterized by smaller length-at-age values than the two other populations which are comprised respectively of spring-spawners and autumn-spawners that are fished off the Gaspé peninsula.Key words: Atlantic herring, St. Lawrence Estuary, Gaspé peninsula, morphometric characteristics, meristic characteristics

Régime alimentaire et principaux facteurs influençant l'alimentation des larves de capelan (Mallotus villosus), d'éperlan (Osmerus mordax) et de hareng (Clupea harengus harengus) dans un estuaire partiellement mélangé

1986 ◽  
Vol 43 (5) ◽  
pp. 968-979 ◽  
Author(s):  
R. Courtois ◽  
J. J. Dodson
Keyword(s):  
Feeding Rate ◽  
Water Masses ◽  
Clupea Harengus ◽  
Gut Contents ◽  
Osmerus Mordax ◽  
Lawrence Estuary ◽  
Daily Cycles ◽  
Food And Feeding ◽  
Clupea Harengus Harengus ◽  
St Lawrence Estuary

The food and feeding rate periodicity of larvae of capelin (Mallotus villiosus), smelt (Osmerus mordax), and herring (Clupea harengus harengus) were studied to determine the existence of potential interactions between the larvae of these three species. Analyses of the gut contents showed that larvae of capelin started to feed before yolk sac absorption but that the feeding rate was low (<20%) in the lower St. Lawrence estuary; the small size of capelin larvae restricted their feeding to tintinnids. Larvae of the two other species feed at a greater rate than capelin larvae and their food is more diverse. The temporal sequence of feeding incidences showed daily cycles for the three species and semidiurnal cycles for larvae of capelin and herring. The importance of light for feeding of larvae was confirmed by the daily cycles and by the greater abundance of larvae with gut contents in surface waters (0–20 m). From the absence of a relation between biotic factors (density of larvae) and the temporal evolution of feeding incidences, we suggest that semidiurnal cycles are mainly related to temperature changes associated with advection of water masses at the sampling stations. Even though similar reactions to certain environmental variables were observed, we concluded that interspecific competition is minimal between larvae of the three species. Although present at the same stations, larvae of different species mainly occurred in distinct water masses; they are also mainly of different size. Those characteristics force them to exploit organisms of different size and mainly of different species.

Spatial Configurations of Young Herring (Clupea harengus harengus) larvae in the St. Lawrence Estuary: Importance of Biological and Physical Factors

1985 ◽  
Vol 42 (S1) ◽  
pp. s91-s104 ◽  
Author(s):  
M. Henri ◽  
J. J. Dodson ◽  
H. Powles
Keyword(s):  
Specific Gravity ◽  
Water Column ◽  
Gravity Current ◽  
Yolk Sac ◽  
Clupea Harengus ◽  
Physical Factors ◽  
Residual Circulation ◽  
Lawrence Estuary ◽  
Clupea Harengus Harengus ◽  
St Lawrence Estuary

The phenomenon of larval retention has recently been identified as central to the structuring of herring stocks. It has been shown that retention of larval fish populations in estuaries is dependent on active vertical migration, the capacity for which develops with growth, but the present study shows that mechanisms for spatial structuring of larval herring (Clupea harengus harengus) populations act at the earliest (yolk sac and post-yolk sac) stages. The study was carried out on the Isle-Verte stock of the St. Lawrence estuary in 1981 and 1982. Length–frequencies and tide-related abundance fluctuations suggested that larvae are retained in the study area. As a result, larvae remain aggregated throughout the sampling period of approximately 1 mo. Yolk sac larvae were significantly more abundant near the bottom than in the water column, while post-yolk sac larvae were significantly less abundant in the suprabenthic layer than in the water column. Larvae, being negatively buoyant, tend to sink in slack water but are transported upwards by turbulence resulting from tidal flows. The extent of vertical transport of larvae in the water column is greatest for larvae with lesser specific gravities; specific gravity is at a maximum at hatching and decreases to a minimum at yolk sac absorption. We conclude that larval specific gravity, current velocity, and the two-layer residual circulation are the major factors causing retention and aggregation of larvae.

scholarly journals Response of the Lower St. Lawrence Estuary to External Forcing in Winter

2006 ◽  
Vol 36 (8) ◽  
pp. 1485-1501 ◽  
Author(s):  
G. C. Smith ◽  
F. J. Saucier ◽  
D. Straub
Keyword(s):  
Low Frequency ◽  
Internal Tides ◽  
Surface Mixed Layer ◽  
Cold Intermediate Layer ◽  
Lawrence Estuary ◽  
Surface Stability ◽  
Tidal Streams ◽  
Harmonic Analyses ◽  
St Lawrence Estuary

Abstract Mostly because of a lack of observations, fundamental aspects of the St. Lawrence Estuary’s wintertime response to forcing remain poorly understood. The results of a field campaign over the winter of 2002/03 in the estuary are presented. The response of the system to tidal forcing is assessed through the use of harmonic analyses of temperature, salinity, sea level, and current observations. The analyses confirm previous evidence for the presence of semidiurnal internal tides, albeit at greater depths than previously observed for ice-free months. The low-frequency tidal streams were found to be mostly baroclinic in character and to produce an important neap tide intensification of the estuarine circulation. Despite stronger atmospheric momentum forcing in winter, the response is found to be less coherent with the winds than seen in previous studies of ice-free months. The tidal residuals show the cold intermediate layer in the estuary is renewed rapidly (14 days) in late March by the advection of a wedge of near-freezing waters from the Gulf of St. Lawrence. In situ processes appeared to play a lesser role in the renewal of this layer. In particular, significant wintertime deepening of the estuarine surface mixed layer was prevented by surface stability, which remained high throughout the winter. The observations also suggest that the bottom circulation was intensified during winter, with the intrusion in the deep layer of relatively warm Atlantic waters, such that the 3°C isotherm rose from below 150 m to near 60 m.

Nearshore Ichthyoplankton of a North Temperate Estuary

1984 ◽  
Vol 41 (11) ◽  
pp. 1653-1663 ◽  
Author(s):  
H. Powles ◽  
F. Auger ◽  
G. J. FitzGerald
Keyword(s):  
Early Life ◽  
Early Life History ◽  
Clupea Harengus ◽  
Winter Flounder ◽  
Nearshore Zone ◽  
Pseudopleuronectes Americanus ◽  
Lawrence Estuary ◽  
Clupea Harengus Harengus ◽  
St Lawrence Estuary ◽  
Spawning Biomass

Composition of ichthyoplankton in the nearshore zone (0–6 km from shore) of the St. Lawrence estuary showed important differences from that farther offshore. In particular, larvae of herring (Clupea harengus harengus), winter flounder (Pseudopleuronectes americanus), and smooth flounder (Liopsetta putnami) made up a greater proportion of the ichthyoplankton than in published surveys farther offshore. Peak catches of larval herring were 1–2 orders of magnitude higher than in offshore waters. Winter flounder and smooth flounder larvae were significantly more abundant [Formula: see text] from shore than 1–6 km offshore; significant abundance gradients were not found for other species. Nearshore areas have received considerably less effort than offshore areas in earlier studies, and we suggest that more intensive studies in the nearshore zone, at least for those species mentioned, would be of importance for elucidating early life history processes and for estimating spawning biomass based on ichthyoplankton surveys.

Capelin (Mallotus villosus) and herring (Clupea harengus) as paratenic hosts of Anisakis simplex, a parasite of beluga (Delphinapterus leucas) in the St. Lawrence estuary

1998 ◽  
Vol 76 (8) ◽  
pp. 1411-1417 ◽  
Author(s):  
Réjean Hays ◽  
Lena N Measures ◽  
Jean Huot
Keyword(s):  
Anisakis Simplex ◽  
Clupea Harengus ◽  
Delphinapterus Leucas ◽  
Intermediate Hosts ◽  
Mallotus Villosus ◽  
Lawrence Estuary ◽  
Third Stage ◽  
Capelin Mallotus Villosus ◽  
Paratenic Hosts ◽  
St Lawrence Estuary

Capelin (Mallotus villosus) (N = 760) and herring (Clupea harengus) (N = 165) were collected in the St. Lawrence estuary during the summer of 1994 and 1995 to examine the importance of pelagic fish in transmission of Anisakis simplex to cetaceans. Larval A. simplex were removed from fish by means of a pepsin-digest solution or by dissection. Prevalence of A. simplex in dissected capelin was 5%, with a mean intensity of 1.2. Prevalences of A. simplex in herring were 95 and 99%, with mean intensities of 6.2 and 6.8 for pepsin digestion and dissection, respectively. Third-stage larval A. simplex found in capelin and herring were compared with third-stage larvae found in euphausiids and belugas (Delphinapterus leucas) from the St. Lawrence estuary and no differences in size or morphology of larvae from these four hosts were observed. Euphausiids, which harboured moulting second-stage and third-stage larvae, are intermediate hosts of A. simplex. As there was no apparent development of larvae in herring or capelin, these fish are considered to be paratenic hosts of A. simplex in the St. Lawrence estuary.

Larval Herring (Clupea harengus) Dispersion, Growth, and Survival in the St, Lawrence Estuary: Match/Mismatch or Membership/Vagrancy?

1990 ◽  
Vol 47 (10) ◽  
pp. 1898-1912 ◽  
Author(s):  
Louis Fortier ◽  
Jacques A. Gagné
Keyword(s):  
Food Availability ◽  
Larval Fish ◽  
Clupea Harengus ◽  
Larval Abundance ◽  
Initial Growth ◽  
Lawrence Estuary ◽  
Growth And Survival ◽  
Relative Contribution ◽  
St Lawrence Estuary

The relative success of the 1985 spring and fall cohorts of Atlantic herring (Clupea harengus) in the St. Lawrence estuary was studied in relation to food availability (match/mismatch hypothesis) and hydrography (member/vagrant hypothesis). The development of the spring cohort (early June) matched remarkably well the development of suitable prey and larval abundance within the estuary decreased slowly (7.8%∙d−1). The fall cohort (mid-September) hatched in a period of low food availability and dwindled rapidly (28.9%∙d−1). The initial growth of both cohorts appeared limited by food. The stratification front limiting seaward drift was strong in the spring (0–80 j∙m−3) and weak in the fall (0–20 J∙m−3), suggesting that advection out of the estuary could also have contributed to the observed differences in the fate of the two cohorts. We conclude from this case study that spawning times and locations may have evolved to favor the initial cohesion of larval fish cohorts by limiting dispersion and that both transport and energetic processes can influence the success of a population at colonizing its dispersion area. The relative contribution of initial vagrancy and subsequent trophic interactions in determining final recruitment remains to be assessed.

scholarly journals Benthic fluxes of dissolved organic nitrogen in the lower St. Lawrence estuary and implications for selective organic matter degradation

2013 ◽  
Vol 10 (11) ◽  
pp. 7609-7622 ◽  
Author(s):  
M. Alkhatib ◽  
P. A. del Giorgio ◽  
Y. Gelinas ◽  
M. F. Lehmann
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Bottom Water ◽  
Estuarine Sediments ◽  
Internal Source ◽  
Lawrence Estuary ◽  
Element Partitioning ◽  
Sediment Porewaters ◽  
St Lawrence Estuary

Abstract. The distribution of dissolved organic nitrogen (DON) and carbon (DOC) in sediment porewaters was determined at nine locations along the St. Lawrence estuary and in the gulf of St. Lawrence. In a previous manuscript (Alkhatib et al., 2012a), we have shown that this study area is characterized by gradients in the sedimentary particulate organic matter (POM) reactivity, bottom water oxygen concentrations, and benthic respiration rates. Based on the porewater profiles, we estimated the benthic diffusive fluxes of DON and DOC in the same area. Our results show that DON fluxed out of the sediments at significant rates (110 to 430 μmol m−2 d−1). DON fluxes were positively correlated with sedimentary POM reactivity and varied inversely with sediment oxygen exposure time (OET), suggesting direct links between POM quality, aerobic remineralization and the release of DON to the water column. DON fluxes were on the order of 30 to 64% of the total benthic inorganic fixed N loss due to denitrification, and often exceeded the diffusive nitrate fluxes into the sediments. Hence they represented a large fraction of the total benthic N exchange, a result that is particularly important in light of the fact that DON fluxes are usually not accounted for in estuarine and coastal zone nutrient budgets. In contrast to DON, DOC fluxes out of the sediments did not show any significant spatial variation along the Laurentian Channel (LC) between the estuary and the gulf (2100 ± 100 μmol m−2 d−1). The molar C / N ratio of dissolved organic matter (DOM) in porewater and the overlying bottom water varied significantly along the transect, with lowest C / N in the lower estuary (5–6) and highest C / N (> 10) in the gulf. Large differences between the C / N ratios of porewater DOM and POM are mainly attributed to a combination of selective POM hydrolysis and elemental fractionation during subsequent DOM mineralization, but selective adsorption of DOM to mineral phases could not be excluded as a potential C / N fractionating process. The extent of this C- versus N- element partitioning seems to be linked to POM reactivity and redox conditions in the sediment porewaters. Our results thus highlight the variable effects selective organic matter (OM) preservation can have on bulk sedimentary C / N ratios, decoupling the primary source C / N signatures from those in sedimentary paleoenvironmental archives. Our study further underscores that the role of estuarine sediments as efficient sinks of bioavailable nitrogen is strongly influenced by the release of DON during early diagenetic reactions, and that DON fluxes from continental margin sediments represent an important internal source of N to the ocean.

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