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Bibliography of the Maurice Lamontagne Institute

Peter GALBRAITH

TAMDRARI, H., M. CASTONGUAY, J.-C. BRÊTHES, P.S. GALBRAITH, D.E. DUPLISEA, 2012. The dispersal pattern and behaviour of Atlantic Cod (Gadus morhua) in the northern Gulf of St. Lawrence : results from tagging experiments. Can. J. Fish. Aquat. Sci., 69(1): 112-121 .

We examined how the distribution of Atlantic cod (Gadus morhua) is influenced by abiotic (temperature, salinity, depth, suitable habitat) and biotic (stock biomass) factors based on tagging–recapture data collected from 1995 to 2008 by the Department of Fisheries and Oceans Canada in the northern Gulf of St. Lawrence. We calculated a centre of gravity index and a dispersion index using only individuals recaptured more than 1 year after tagging during the summer. The centre of gravity showed a northward expansion and eastward contraction in recent years, reflecting both fish distribution and changes in fishing effort. The dispersion index was significantly related to temperature, habitat suitability, and biomass but not to salinity or depth. These results indicate that interannual fluctuations of temperature and stock abundance both influence the dispersion pattern of cod. This new information could influence spatio-temporal fisheries management strategies for northern Gulf cod.©2012 NRC Research Press

CYR, F., D. BOURGAULT, P.S. GALBRAITH, 2011. Interior versus boundary mixing of a cold intermediate layer. J. Geophys. Res. (C Oceans), 116(12). Art. no C12029, 12 p .

The relative importance of interior versus boundary mixing is examined for the erosion of the cold intermediate layer (CIL) of the Gulf of St. Lawrence. Based on 18 years of historical temperature profiles, the seasonal erosion of the core temperature, thickness and heat content of the CIL are, respectively, Tmin = 0.24 ±0.04 °C mo-1, dmin = -11 ± 2 m mo-1 and H = 0.59 ± 0.09 MJ m-3 mo-1. These erosion rates are remarkably well reproduced with a one–dimensional vertical diffusion model fed with turbulent diffusivities inferred from 892 microstructure casts. This suggests that the CIL is principally eroded by vertical diffusion processes. The CIL erosion is best reproduced by mean turbulent kinetic energy dissipation rate and eddy diffusivity coefficient of ? ≅ 2 × 10-8 W kg-1 and K ≅ 4 × 10-5 m2 s-1, respectively. It is also suggested that while boundary mixing may be significant it may not dominate CIL erosion. Interior mixing alone accounts for about 70 % of this diffusivity with the remainder being attributed to boundary mixing. The latter result is in accordance with recent studies that suggest that boundary mixing is not the principal mixing agent in coastal seas.© 2011 American Geophysical Union

GALBRAITH, P.S., J. CHASSÉ, D. GILBERT, P. LAROUCHE, D. BRICKMAN, B. PETTIGREW, L. DEVINE, A. GOSSELIN, R.G. PETTIPAS, C. LAFLEUR, 2011. Physical oceanographic conditions in the Gulf of St. Lawrence in 2010 ; Conditions océanographiques physique dans le golfe du Saint-Laurent en 2010. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2011/045, 86 p .

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An overview of physical oceanographic conditions in the Gulf of St. Lawrence in 2010 is presented. Air temperatures reached record highs when averaged from January to March and from October through December as well as annually. The monthly averaged freshwater runoff measured at Québec City was normal overall in 2010 but was unusually high during winter and fall, and the spring freshet was almost absent. Near-surface water temperatures in the Gulf were normal or above normal all year and in all regions except for the Mécatina Trough and Esquiman Channel in June. Maximum sea-ice volume within the Gulf and on the Scotian Shelf was 11 km³, a record low since 1969. The duration of the 2009–2010 ice season was shorter than normal and associated with the early ice melt. Winter inflow of cold and saline water from the Labrador Shelf occupied the Mécatina Trough over the entire column in winter 2010. The spread of the intrusion was confined close to the Strait of Belle Isle, leading to an overall small volume of 809 km³. However, this intrusion volume represented 29 % of the unusually small volume of mixed layer waters that were colder than -1 °C. The winter cold mixed layer volume in the Gulf, excluding the Estuary, was 13 900 km³, a value higher than the 1996–2009 average by 0.7 SD. This cold-water volume corresponded to 42 % of the total water volume of the Gulf. However, it was very warm, on average about 1 °C above the freezing point. This is the first time in 15 years of winter surveys that such high temperatures were recorded. The cold intermediate layer (CIL) index for summer 2010 was - 0.04 °C, which is similar to observations in 2000. This is an increase of 0.38 °C since 2009. On the Magdalen Shallows, none of the bottom area was covered by water with temperatures < 0 °C in September 2010, similar to conditions in 2005, 2006, 2007, and 2009. In other regions of the Gulf, very few areas had bottom temperatures below 0 °C. Regional patterns of the August and September CIL show that the layers for T < 1 °C and < 0 °C were much thinner in most parts of the Gulf in 2010 than in 2009 and had a generally higher core temperature everywhere. Conditions in March 2010 were characterized by a very thick winter mixed layer, although very warm, including a thick intrusion of Gulf waters into the Estuary. By June 2010, the CIL thickness returned to nearnormal but still had above-normal minimum temperatures. The CIL warming rate appeared to be slower than usual because core temperatures were closer to normal in certain regions by August and more so by November. The warm deep waters in the Estuary in 2009 were replaced by colderthan- normal waters by June 2010. Colder-than-normal deep waters also occupied the northwest Gulf at that time. Very warm waters occupied Cabot Strait in June at 250 m—the depth of the temperature maximum—and there is a hint that the top portion of this water mass was sampled during the March survey. The warm deep waters were still present in Cabot Strait in August as well as in November. Gulf-wide average temperatures were below normal at 200 to 300 m and salinities were below normal from 150 to 300 m. Temperatures at 300 m increased marginally overall but significantly (by 1 SD) at Cabot Strait, where the anomaly is now +1 SD. Salinity at 200 m and 300 m decreased overall by 0.6 SD but increased at Cabot Strait to reach +0.6 SD at 200 m. The 300 m waters of the Estuary are expected to cool further during the next two years, but it will be interesting to follow the warm anomaly present in 2010 at Cabot Strait as it progresses up the channel toward the Estuary. The surface mixed layer in November was anomalously thick but more importantly very warm, warmer in fact than in November 2009 which were the preconditions for the record conditions of March 2010.

BOURGAULT, D., C. HAMEL, F. CYR, J.-E. TREMBLAY, P.S. GALBRAITH, D. DUMONT, Y. GRATTON, 2011. Turbulent nitrate fluxes in the Amundsen Gulf during ice-covered conditions. Geophys. Res. Lett., 38(15): Art. no. L15602 .

GALBRAITH, P.S., P. LAROUCHE, 2011. Sea-surface temperature in Hudson Bay and Hudson Strait in relation to air temperature and ice cover breakup, 1985-2009. J. Mar. Syst., 87(1) 66-78 .

Sea-surface weekly average temperatures derived from NOAA–AVHRR remote sensing data are analyzed for the period 1985–2009 for Hudson Bay and Hudson Strait, and compared to weekly ice cover data obtained from the Canadian Ice Service for the period 1971–2009 as well as to monthly average air temperature at four stations around Hudson Bay and to four around Hudson Strait. Results show a decreasing trend in the breakup date of the sea-ice in Hudson Strait of 5.6 days per decade since 1971 as well as an interannual variability of 5 °C in the Hudson Bay average SST in August between extreme years. There is good correlation in Hudson Bay between average SST in August and average air temperature anomalies at four meteorological weather stations (R2=0.80) and with the percentage of open water from June to August (R2=0.80). Climatology for SST of the warmest week of the year is presented, and the variability of different regions within Hudson Bay is discussed. One area in southwestern Hudson Bay is shown to exhibit the highest interannual variability, having nearly the warmest surface waters in some years and nearly the coldest in others. The historical observed variability of SST and ice cover is compared to expected changes in the literature that are associated with climate change.©2011 Elsevier B.V.

GALBRAITH, P.S., P. LAROUCHE, 2011. Reprint of "Sea-surface temperature in Hudson Bay and Hudson Strait in relation to air temperature and ice cover breakup, 1985-2009". J. Mar. Syst., 88(3) 463-475 .

Sea-surface weekly average temperatures derived from NOAA-AVHRR remote sensing data are analyzed for the period 1985-2009 for Hudson Bay and Hudson Strait, and compared to weekly ice cover data obtained from the Canadian Ice Service for the period 1971-2009 as well as to monthly average air temperature at four stations around Hudson Bay and to four around Hudson Strait. Results show a decreasing trend in the breakup date of the sea-ice in Hudson Strait of 5.6 days per decade since 1971 as well as an interannual variability of 5 °C in the Hudson Bay average SST in August between extreme years. There is good correlation in Hudson Bay between average SST in August and average air temperature anomalies at four meteorological weather stations (R2=0.80) and with the percentage of open water from June to August (R2=0.80). Climatology for SST of the warmest week of the year is presented, and the variability of different regions within Hudson Bay is discussed. One area in southwestern Hudson Bay is shown to exhibit the highest interannual variability, having nearly the warmest surface waters in some years and nearly the coldest in others. The historical observed variability of SST and ice cover is compared to expected changes in the literature that are associated with climate change. © 2011 Published by Elsevier B.V.

GALBRAITH, P.S., R.G. PETTIPAS, J. CHASSÉ, D. GILBERT, P. LAROUCHE, B. PETTIGREW, A. GOSSELIN, L. DEVINE, C. LAFLEUR, 2010. Physical Oceanographic Conditions in the Gulf of St. Lawrence in 2009 Conditions d’océanographie physique dans le golfe du Saint-Laurent en 2009. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2010/035, 77 p .

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An overview of physical oceanographic conditions in the Gulf of St. Lawrence in 2009 is presented. Air temperatures were close to normal when averaged from January to March. Air temperatures were in general either normal or above normal for the remainder of the year. The monthly averaged freshwater runoff measured at Québec City was normal overall in 2009 but consisted of aboveaverage runoff in July compensated later by lower runoff in the fall. Near-surface water temperatures in the Gulf were above normal in all regions except the Northwest Gulf and the Estuary in June and in every region in August. Maximum sea-ice volume within the Gulf and on the Scotian Shelf was 65 km³, a value that is below normal using updated ice volume estimates for 1971-2000. The duration of the 2008-09 ice season was longer than normal in the Estuary, normal in the central Gulf and Cabot Strait, and shorter elsewhere. This was mostly associated with the variability of the first occurrence of ice. Winter inflow of cold and saline water from the Labrador Shelf occupied the Mécatina Trough over the entire column in winter 2009. The spread of the intrusion was confined a bit closer to the coast compared to 2008 conditions, leading to an overall smaller volume of 1270 km³, which is similar to the 2002 observations. The winter cold mixed layer volume in the Gulf, excluding the Estuary, was 14 000 km³, a value higher than the 1996–2009 average by 0.7 SD. This cold-water volume corresponded to 42% of the total water volume of the Gulf. The cold intermediate layer (CIL) index for summer 2009 was -0.42°C, which is similar to observations in 2002, 2004, 2005 and 2007. This is an increase of 0.32°C since 2008. On the Magdalen Shallows, almost none of the bottom area was covered by water with temperatures < 0°C in September 2009, similar to conditions in 2005, 2006 and 2007. Regional patterns of the August and September CIL show that the layers for T < 1°C and < 0°C were much thinner in most parts of the Gulf in 2009 than in 2008 and had a generally higher core temperature everywhere. In the northern Gulf, the area covered by low temperature water (< 1°C) decreased in 2009 relative to 2008 conditions. Temperatures in March 2009 were characterized by a very thick cold layer, including a thick intrusion of Gulf CIL waters into the Estuary. By June 2009, CIL temperatures returned to normal with a warming trend that continued into August, especially on the Magdalen Shallows. By October–November, CIL conditions were normal in most regions except the estuary and Northwest Gulf, where the CIL and the surface mixed layer were anomalously deep. Overall, temperature and salinity were generally normal from 150 m to 200 m, and slightly lower than normal at 250 and 300 m. Temperature and salinity at 300 m decreased for a third consecutive year, from 2008 to 2009. The lower-than-normal Gulf-wide water temperatures at 300 m were composed of normal waters in the Estuary and northwest and colder waters in the centre and coming into the Gulf at Cabot Strait. This cold anomaly has propagated inward in the last few years and is expected to continue toward the Estuary during the next few years.

DUFOUR, R., H. BENOIT, M. CASTONGUAY, J. CHASSÉ, L. DEVINE, P. GALBRAITH, M. HARVEY, P. LAROUCHE, S. LESSARD, B. PETRIE, L. SAVARD, C. SAVENKOFF, L. ST-AMAND, M. STARR, 2010. Rapport sur l'état et les tendances des écosystèmes marins canadiens en 2010. MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2010/030(révisé), 43 p .

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DUFOUR, R., H. BENOIT, M. CASTONGUAY, J. CHASSÉ, L. DEVINE, P. GALBRAITH, M. HARVEY, P. LAROUCHE, S. LESSARD, B. PETRIE, L. SAVARD, C. SAVENKOFF, L. ST-AMAND, M. STARR, 2010. 2010 Canadian marine ecosystem status and trends report. Advis. Sec. Sci. Advis. Rep. 2010/030(Revised), 38 p .

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DUFOUR, R., H. BENOIT, M. CASTONGUAY, J. CHASSÉ, L. DEVINE, P. GALBRAITH, M. HARVEY, P. LAROUCHE, S. LESSARD, B. PETRIE, L. SAVARD, C. SAVENKOFF, L. ST-AMAND, M. STARR, 2010. Ecosystem status and trends report: Estuary and Gulf of St. Lawrence ecozone. Rapport sur l’état et les tendances des écosystèmes : écozone de l’estuaire et du golfe du Saint Laurent. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche; 2010/030, 193 p .

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This document was produced under the umbrella of the national ecosystem status and trends report program and deal with the estuary and gulf of St.Lawrence ecozone. It is structured around the status and trends of some important marine species and physico-chemical variables of the ecosystem. The national ecosystem status and trends report will support prioruty-setting for a national biodiversity agenda and will integrate national and provincial exosystem-bases information. It will report on many large terrestrial and marine ecozones.

HARVEY, M., P.S. GALBRAITH, A. DESCROIX, 2009. Vertical distribution and diel migration of macrozooplankton in the St. Lawrence marine system (Canada) in relation with the cold intermediate layer thermal properties. Prog. Oceanogr., 80(1-2): 1-21 .

Vertical distribution of various species and stages of macrozooplankton (euphausiacea, chaetognatha, cnidaria, mysidacea, amphipoda) were determined for different times of the day and related to the physical environment. Stratified sampling with the BIONESS was carried out during seven cruises in spring and fall 1998, 2000, and 2001, and fall 1999, in two different habitats in the St. Lawrence marine system: the lower St. Lawrence Estuary and the NW Gulf of St. Lawrence. Our results indicate that the various macrozooplankton species were distributed throughout the whole water column including the surface layer, the cold intermediate layer (CIL), and the deep layer at different times of day and night in both areas during all periods. Moreover, three types of migrational patterns were observed within this zooplanktonic community: (1) nocturnal ascent by the whole population, (2) segregation into two groups; one which performed nocturnal accent and another which remained in the deep, and (3) no detectable migration. We also observed that the diel vertical migration (DVM) amplitude in most of the macrozooplankton species varied as a function of physical factors, in particular the spatio-temporal variations of the CIL thermal properties, including the upper and the lower limits of the CIL and the depth of the CIL core temperature. Finally, the different DVM patterns coupled with estuarine circulation patterns and bottom topography could place animals in different flow regimes by night and by day and contribute to their retention (aggregation) and/or dispersion in different areas, time of the day, and seasons. Crown Copyright ©2008 Published by Elsevier Ltd.

HARVEY, M., P. GALBRAITH, 2009. Macrozooplankton diel migration in the Estuary and Gulf of St. Lawrence : links to abiotic factors. AZMP Bull. PMZA, 8: 28-35 .

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GALBRAITH, P., R.G. PETTIPAS, J. CHASSÉ, D. GILBERT, P. LAROUCHE, B. PETTIGREW, A. GOSSELIN, L. DEVINE, C. LAFLEUR, 2009. Physical oceanographic conditions in the Gulf of St. Lawrence in 2008 ; Conditions d’océanographie physique dans le golfe du Saint-Laurent en 2008. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2009/014, 73 p .

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An overview of physical oceanographic conditions in the Gulf of St. Lawrence in 2008 is presented. Air temperatures were close to normal when averaged from January to March, contributing to an ice cover volume that was also close to the climatological mean. Air temperatures were in general either normal or above normal for the remainder of the year. The monthly averaged freshwater runoff measured at Québec City was normal overall in 2008, but consisted of above-average runoff in summer compensated later by lower runoff in the fall. The high summer runoff contributed to higher-than-normal stratification. Near-surface water temperatures were generally above normal throughout the Gulf for the months of May, July and November and were also above-normal on the Magdalen Shallows in June and in the northern Gulf from August to October. In August the northern parts of the Gulf saw positive anomalies while the southern parts experienced negative anomalies. This lead to the unusual occurrence that the waters around Prince Edward Island and in Northumberland Strait had higher temperature in July than in August 2008. On the Magdalen Shallows, a large area of the bottom was covered by water with temperatures < 0 °C in September 2008, similar to the cold period observed in the 1990s and in contrast to conditions in September 2005, 2006 and 2007 when such cold waters were not observed. Maximum sea-ice volume within the Gulf and on the Scotian Shelf was 81 km3, a value now considered about normal using updated ice volume estimates for 1971-2000. Ice first appeared early in the season and stayed later than normal (later by about 8 days later on the Magdalen Shallows). Winter inflow of cold and saline water from the Labrador Shelf occupied the Mécatina Trough from top to bottom in winter 2008. The spread of the intrusion was confined a bit closer to the coast compared to 2007 conditions, leading to an overall smaller volume of 1850 km3, which is similar to 2001 and 2006 observations. The winter cold mixed layer volume was 13 700 km3, a value higher than the 1996–2008 average by 0.8 SD, and corresponded to 41 % of the total water volume of the Gulf. The summer CIL (cold intermediate layer) index for 2008 was -0.70 °C, comparable to the very cold conditions observed in 2003 and a large decrease (by 0.47 °C) from the previous summer. Regional patterns of the August and September CIL show that the layers for T < 1 °C and < 0 °C were much thicker in most parts of the Gulf in 2008 than in 2007 and had a generally lower core temperature throughout the Gulf. In the Northern Gulf, the area covered by water of low temperature (from < -1 °C through < 1 °C) increased in August 2008 relative to August 2007. Temperatures in the water column in June 2008 were characterized by a very thick and cold CIL in most regions except the Estuary and by warm deep waters in the Estuary and the northwest Gulf. This overall pattern persisted in the August– September mean conditions. By October and into November, CIL conditions were still thick and cold, while waters above the CIL were anomalously warm. Overall, temperature and salinity were generally normal from 150 m to 300 m, with the exception of slightly lower than normal (by 0.6 SD) temperature at 150 m. Temperature and salinity in this depth range decreased for a second consecutive year. The near-normal Gulf-wide water temperatures at 300 m were composed of warmer waters in the Estuary, near-normal temperatures in the northwest and central, and colder waters flowing into the Gulf at Cabot Strait.

GALBRAITH, P.S., 2009. State of the ocean 2008 : physical oceanographic conditions in the Gulf of St. Lawrence. DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2009/019, 19 p .

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GALBRAITH, P.S., 2009. État de l'océan en 2008 : conditions océanographiques physiques dans le golfe du Saint-Laurent. MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2009/019, 20 P .

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DUTIL, J.-D., P. DUMONT, D.K. CAIRNS, P.S. GALBRAITH, G. VERREAULT, M. CASTONGUAY, S. PROULX, 2009. Anguilla rostrata glass eel migration and recruitment in the estuary and Gulf of St Lawrence. J. Fish. Biol., 74: 1970-1984 .

This study describes catches of Anguilla rostrata glass eels and associated oceanographic conditions in the St Lawrence Estuary and Gulf. Ichthyoplankton survey data suggest that they enter the Gulf primarily in May, migrate at the surface at night, and disperse broadly once they have passed Cabot Strait. T hey arrive in estuaries beginning at about mid-June and through the month of July. Migration extends west up to Quebec City, in the freshwater zone of the St Lawrence Estuary, 1000 km west of Cabot Strait. Anguilla roslrata glass eels travel between Cabot Strait and receiving estuaries at a straight-line ground speed of c. 10–15 km day-1. Catches of fish per unit effort in estuaries in the St Lawrence system are much lower than those reported for the Atlantic coast of Canada. Low abundance of A. rostrata glass eels in the St Lawrence system may be due to cold surface temperatures during the migration period which decrease swimming capacity, long distances from the spawning ground to Cabot Strait and from Cabot Strait to the destination waters (especially the St Lawrence River), complex circulation patterns, and hypoxic conditions in bottom waters of the Laurentian Channel and the St Lawrence Estuary.©2009 The Fisheries Society of the British Isles

GALBRAITH, P., 2008. État de l’océan en 2007 : conditions océanographiques physiques dans le golfe du Saint-Laurent. MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2008/016, 13 p .

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GALBRAITH, P., 2008. State of the ocean 2007: physical oceanographic conditions in the Gulf of St. Lawrence. DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2008/016, 19 p .

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GALBRAITH, P.S., D. GILBERT, R.G. PETTIPAS, J. CHASSÉ, C. LAFLEUR, B. PETTIGREW, P. LAROUCHE, L. DEVINE, 2008. Physical oceanographic conditions in the Gulf of St. Lawrence in 2007 ; Conditions d'océanographie physique dans le golfe Saint-Laurent en 2007. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2008/001, 59 p .

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An overview of physical oceanographic conditions in the Gulf of St. Lawrence in 2007 is presented. Air temperatures ranged from normal to cooler than normal for most of the year in the western parts of the Gulf; however, the eastern regions were only significantly cooler than normal in April and May. Averaged over the whole Gulf for the entire year, air temperature was normal. The monthly averaged runoff at Québec City was below normal during all months of 2007. Near-surface water temperatures were much cooler in 2007 overall than in 2006 in all regions of the Gulf. Near-surface waters were warm in the St. Lawrence Estuary in January and February. Summer maximum surface temperatures occurred earlier than usual, followed by earlier-than-usual cooling. Surface temperatures were generally below normal for the rest of the year except for October in the Estuary. On the Magdalen Shallows, there was (almost) no bottom area covered by water with temperatures <0 °C in September 2007. Maximum sea-i ce volume within the Gulf and on the Scotian Shelf was below normal but still much higher than the volume recorded in 2006. Winter inflow of cold and saline water from the Labrador Shelf occupied the Mecatina Trough from top to bottom. The spread of the intrusion had an area similar to that of 2006, but its volume was much larger and similar to that observed in 2004. The winter cold mixed layer volume was 13100 km3, slightly above the 1996-2007 average, and corresponded to 39 % of the total water volume of the Gulf. The higher winter volume of cold water compared with 2006 conditions led to a decrease of 0.44 °C in the Cold Intermediate Layer (CIL) index, reaching -0.23 °C in summer 2007, which is comparable to conditions observed in 2004. The index saw a large decrease after three consecutive years of warming. Regional patterns of the CIL show that the layer for T < 1 °C and < 0  °C was much thicker in the northern half of the Gulf in 2007 than in 2006 and had a generally lower core temperature almost everywhere as well. Seasonal and regional patterns of water column temperatures in June were generally close to the 1971-2000 climatology at all depths, except for the very thick and cold CIL in the Anticosti Channel and warm deep waters in the northwest. This overall pattern persisted from August to September, but by late fall conditions were about normal everywhere except for the anomalously warm nearsurface mixed layers in the northwest and warm near-surface waters on the Magdalen Shallows and in Cabot Strait. Averaged annually for the entire Gulf, the temperature and salinity from 150 m to 300 m were normal in 2007. Spatially, at 300 m, this was composed of warmer than normal waters near the Estuary, near-normal temperatures in the centre and colder than normal waters coming into the Gulf at Cabot Strait. The outlook for 2008 from the March 2008 survey is for a slight cooling of the CIL index to -0.47 °C resulting from a thicker cold winter surface layer.

BOURGAULT, D., D.E. KELLEY, P.S. GALBRAITH, 2008. Turbulence and boluses on an internal beach. J. Mar. Res., 66(5): 563-588 .

In a manner similar to that of surface waves on beaches, high-frequency interfacial waves (Iws) may break when approaching the 'internal coastline,' where the undisturbed pycnocline intersects the shoaling bottom. This process has been studied previously in idealized laboratory and numerical experiments but there are few field observations to document the properties of Iws shoaling on natural internal beaches. This paper presents observations of currents, density and turbulence collected inshore of the break point of an internal beach of the St. Lawrence Estuary. A series of large- and small-amplitude complex-shaped and unorganized internal boluses was observed. The structure of these boluses is discussed, along with their role in boundary turbulence and transport.

GALBRAITH, P., 2007. State of the ocean 2006 : physical oceanographic conditions in the Gulf of St. Lawrence. DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2007/036, 12 p .

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GALBRAITH, P.S., D. GILBERT, C. LAFLEUR, P. LAROUCHE, B. PETTIGREW, J. CHASSÉ, R.G. PETTIPAS, W.M. PETRIE, 2007. Physical oceanographic conditions in the Gulf of St. Lawrence in 2006 ; Conditions d'océanographie physique dans le golfe Saint-Laurent en 2006. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2007/024, 51 p .

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An overview of physical oceanographic conditions in the Gulf of St. Lawrence in 2006 is presented. Air and surface water temperatures were above normal except for late summer in most parts of the Gulf. Bottom water temperatures on the Magdalen Shallows were unusually warm; no observations below 0 °C were recorded in September. The yearly total freshwater runoff at Québec City was normal but included an anomalous strong fall peak. Sea ice coverage and volume within the Gulf during the winter was the lowest recorded since 1969. The winter cold mixed layer volume was the smallest recorded in the 11 year history of the winter helicopter survey and corresponded to 29 % of the total water volume of the Gulf. This shallow winter mixed layer led to the CIL index for summer 2006 increasing to +0.21 °C. This is the warmest value since 1983, but only 0.1 °C warmer than in 2000 which was the second warmest. Regional patterns of the CIL minimum temperatures show that increases between 2005 and 2006 were more pronounced in the Laurentian Channel than elsewhere. The minimum temperature actually decreased in Mecatina Trough, presumably due to the increased inflow of a thick layer of cold and highly saline water, which was observed from the annual March survey, through the Strait of Belle Isle. Regional patterns similar to those found for the CIL minimum temperatures were seen in the regional CIL thickness distribution. The CIL volume (T <1 °C) for the Magdalen Shallows during the September groundfish survey was the lowest since 1982. Water temperatures were generally one standard deviation above the mean, based on the 1971-2000 climatology at all depths for most of the year. Exceptions to this included the CIL in Esquiman Channel and Mecatina Trough and the deeper waters (>300 m) of the southern half of the Laurentian Channel which were colder. The most noteworthy thermal features in November were the anomalously deep CIL in the Estuary and northwestern Gulf regions and the anomalously warm waters above the CIL everywhere in the Gulf. The outlook for 2007 based on the March 2007 survey is for a 0.6 °C cooling of the summer CIL index forecast from a thicker winter cold surface layer and increased inflow of Labrador Shelf water through the Strait of Belle Isle.

GALBRAITH, P., 2007. État de l'océan en 2006 : conditions d'océanographie physique dans le golfe du Saint-Laurent. MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2007/036, 13 p .

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GALBRAITH, P.S., R. DESMARAIS, R. PIGEON, S. CANTIN, 2006. Ten years of monitoring winter water masses in the Gulf of St. Lawrence by helicopter. AZMP Bull. PMZA, 5: 32-35 .

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[Abstract only available in French]
Une mission océanographique héliportée a lieu à la fin de l’hiver dans le golfe du Saint-Laurent depuis maintenant dix ans. Cette mission a permis de monitorer les conditions extrêmes froides du Golfe ainsi que leurs variabilités interannuelles, et ce de façon plus représentative qu’avec les anciennes données qui étaient biaisées vers des conditions d’échantillonnage libre de glace. L’évolution des techniques d’échantillonnage est décrite, des premières années où le travail se faisait après avoir atterrie sur la glace, pour terminer avec un échantillonnage fait en grande majorité en vol stationnaire à l’aide d’un treuil électrique. L’efficacité de l’hélicoptère comme plate-forme pour ces travaux légers est sommairement discutée. Des résultats typiques de la mission sont présentés, tels que préparés pour l’examen annuel de l’état océanographique du golfe du Saint-Laurent. Ceux-ci inclus une prévision de l’indice de la couche intermédiaire froide (CIF) calculée à partir du volume total d’eau froide observé lors de la mission d’hiver. Ces données d’hiver aident à comprendre pourquoi les variations de la CIF se produisent.

GALBRAITH, P.S., 2006. Winter water masses in the Gulf of St. Lawrence. J. Geophys. Res. (C Oceans), 111, art. no C06022, 23 p .

The first 9 years of data collected during a new late-wintertime hydrographic survey of the Gulf of St. Lawrence are presented. They show colder conditions than those previously measured from ships that were likely biased towards warmer ice-free waters. The total volume of cold water (< -1C) varied inter-annually from 10000 to 15000 cubic km and is a good predictor for the following summertime Cold Intermediate Layer index. The volume of cold and saline Labrador Shelf waters that inflowed through the Strait of Belle Isle is estimated using two temperature-salinity criteria. It exhibits much stronger inter-annual variability than the total cold water volume, representing from 5 % to as much as 30 % of all cold surface waters. It was sometimes observed to reach the bottom in Mecatina Trough at more than 200 m depth, where deep waters are isolated from the rest of the Gulf.© 2006The American Geophysical Union.

DESCROIX, A., M. HARVEY, S. ROY, P.S. GALBRAITH, 2005. Macrozooplankton community patterns driven by water circulation in the St. Lawrence marine system, Canada. Mar. Ecol. Prog. Ser., 302: 103-119 .

Six cruises were carried out in the lower St. Lawrence Estuary (LSLE) and the NW Gulf of St. Lawrence (NW GSL) in spring and fall 1998, 2000, and 2001 to study the species composition, abundance, and distribution of macrozooplankton in relation to the physical environment. Our results confirm that the LSLE and the NW GSL represent 2 different physical environments. These differences are likely due to different circulation patterns observed between the 2 regions: the estuarine circulation in the LSLE and a quasi-permanent cyclonic gyre in the NW GSL. The dominant species found in both environments (LSLE and NW GSL) is the mysid Boreomysis arctica, but we observed no significant regional and interannual variations in its abundance. In contrast, 2 distinct groups characterized the LSLE and the NW GSL when we examined the other macrozooplankton groups. Two euphausiid species, Meganyctiphanes norvegica and Thysanoessa raschii, dominated in the LSLE. Their abundances were 6 and 15 times higher in the LSLE than in the NW GSL, respectively. On the other hand, the NW GSL was dominated by chaetognaths, hyperiid amphipods, and siphonophores. These groups were twice as abundant in the NW GSL as in the LSLE. Such interregional variations were attributed to different circulation patterns and different trophic systems. Furthermore, important interannual variations in the abundance of the major macrozooplankton species were also observed between 1998 and 2001 in the LSLE and the NW GSL. In the NW GSL, the arctic and boreo-arctic species were more abundant in 1998 than in 2000 and 2001. In contrast, their abundance was lowest in 1998, and highest in 2000 and 2001 in the LSLE. We hypothesize that stronger inflow of Labrador Shelf waters in the GSL via the Strait of Belle Isle may increase the advection of macrozooplankton into the LSLE.©2005 Inter-Research

BOURGAULT, D., D.E. KELLEY, P.S. GALBRAITH, 2005. Interfacial solitary wave run-up in the St. Lawrence Estuary. J. Mar. Res., 63(6): 1001-1015 .

Density variations show evidence of interfacial solitary waves (ISW) running up the sloping boundary of an island in the St. Lawrence Estuary, confirming inferences based remote sensing. Further detail is suggested by simulations created with a two-dimensional nonhydrostatic numerical model. The simulations confirm theoretical predictions of the location of wave breaking, something that is difficult to observe in the field. Two other results of the simulations match laboratory findings: the creation of turbulent boluses that propagate upslope of the breaking zone, and the creation of an intermediate layer that transports mixed water away from the mixing site. Although our sampling could not resolve the intermediate mixing layer, it did provide evidence of boluses. In addition to ISW breaking the bolus and intrusion effects may also be important in coastal regions

GALBRAITH, P., H.I. BROWMAN, R.G. RACCA, A.B. SKIFTESVIK, J.-F. SAINT-PIERRE, 2004. Effect of turbulence on the energetics of foraging in Atlantic cod Gadus morhua larvae. Mar. Ecol. Prog. Ser., 281: 241-257 .

A net energy gain (NEG) model was used to assess the effects of turbulence on the energy budget of Atlantic cod Gadus morhua larvae, feeding on copepod nauplii at different concentrations.The geometry of their prey search space was parameterised as either a sphere, hemisphere (the most commonly applied in analogous studies), or wedge. Observed distributions in behaviour (e.g. move duration, pause duration, turn angles) were used as model input, and 2 facets of this behaviour (move duration and move speed) were varied to examine how parameterised changes in foraging behaviour can affect the NEG of the predator. At a prey concentration of 100 l-1, and in static water, NEG is an order of magnitude higher for a hemispherical shape relative to a wedge-shaped search volume. This difference decreases with increasing prey concentration (600 l-1), but always remains considerable. When parameterised turbulence was added, prey capture rates for a larva with a hemispherical search space increases 3 times as much as for a larva with a wedge-shaped search space (typically a 50 % increase using the hemisphere vs 15 % using a wedge). Thus, when this one key assumption (the search volume shape) of current turbulence-effects models is more realistically parameterised, the theorized advantage of turbulence is greatly reduced (at the level of the animal’s prey capture and NEG). This result demonstrates the need to carefully reassess the underlying assumptions of current turbulence-effects models and, therefore, the conclusions that have been based upon those models. Our NEG model also demonstrates the energetic benefits of certain changes in larval behaviour—such as shorter move durations—which lead to a more thorough and cost-effective search of the surrounding water for larvae with a wedge-shaped search volume. This latter effect is not observed for predators with spherical or hemispherical search volumes. These results indicate that it would be prudent to reconsider the conclusions of any previous study that was based upon over-simplified search space geometries. ©2004 Inter-Research

STARR, M., L. ST-AMAND, L. DEVINE, L. BÉRARD-THERRIAULT, P.S. GALBRAITH, 2004. State of phytoplankton in the Estuary and Gulf of St. Lawrence during 2003 ; État du phytoplancton dans l’estuaire et le golfe du Saint-Laurent en 2003. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2004/123, 35 p .

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We reviewed information concerning the seasonal and interannual variations in the concentrations of chlorophyll a, nitrates, and silicates as well as the abundance of the major species of phytoplankton measured at three fixed stations (Rimouski, Anticosti Gyre, and Gaspé Current) and six sections crossing the Estuary and Gulf of St. Lawrence. We concentrated on conditions prevailing in 2003 but also compared those observations with previous information from the 1992-2002 period. In 2003, the initiation of the major phytoplankton bloom at Station Rimouski in the Lower St. Lawrence Estuary occurred in late May, which is one month earlier than usual. Excluding 2002, this continued a trend that began in 1998. This major shift in the timing of the phytoplankton cycle is believed to be due to the below-normal spring freshwater runoff that has been generally observed in the St. Lawrence basin since 1998. The average phytoplankton biomass during spring-summer 2003 at Station Rimouski was also higher compared to 1992-1994, 1996, 1998, and 2000-2002, but lower compared to 1995, 1997, and, more especially, to 1999. Spring-summer phytoplankton production measured at this station was also much higher in 2003 compared to the previous three years but lower than in 1999. At the Anticosti Gyre and the Gaspé Current stations, nitrate and silicate concentrations were high in late fall-winter and low in late spring-summer due to biological consumption by phytoplankton. For both stations, the reduction of nutrients in the surface layer during spring-summer was much more pronounced in 2003 compared to the 2000-2002 period. Thus based on the evolution of nutrients, phytoplankton production in the northwestern Gulf of St. Lawrence could have been higher in 2003 compared to the previous three years. This is consistent with data from Station Rimouski in the Lower St. Lawrence Estuary. Similarly, the surface nutrient levels in late winter 2003 were also higher in the southern and northeastern Gulf of St. Lawrence compared to the previous two years while levels were not markedly different for the late spring-summer period. This suggests again that the spring phytoplankton bloom in these regions was also more intense in 2003 compared to recent years. For a third consecutive year, the analysis of the phytoplankton community composition in 2003 revealed the presence of the diatom Neodenticula seminae in many areas of the Gulf of St. Lawrence, with concentrations up to 197 X 102 cells per litre. This phenomenon is unusual since this species is typically found in North Pacific waters. In the Atlantic Ocean, this species has only been recorded in middle to high latitude Quaternary sediments, dating from between 0.84 and 1.2 million years ago. It is proposed that this Pacific species was introduced naturally into the Gulf (across the Arctic, down the Labrador Current, and through Strait of Belle Isle) rather than via ballast waters. The invasion of N. seminae on the Atlantic coast is consistent with recent observations suggesting a greater influx of Pacific waters into the Atlantic.

GILBERT, D., P.S. GALBRAITH, C. LAFLEUR, B. PETTIGREW, 2004. Physical Oceanographic Conditions in the Gulf of St. Lawrence in 2003 ; Conditions d’océanographie physique dans le golfe Saint-Laurent en 2003. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2004/061, 63 p .

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An overview of physical oceanographic conditions in the Gulf of St. Lawrence in 2003 is presented. Air temperatures and surface water temperatures were below normal in winter and above normal in the fall. During winter 2003, sea ice coverage within the Gulf was about 10 % above the long-term mean, the first year above normal since 1995. But of more significance, a record amount of ice was advected out of the Gulf through Cabot Strait during winter 2003, and the total volume of ice formation in the Gulf was much higher than normal. Moreover, the inflow of water through the Strait of Belle Isle in the northeast Gulf was by far the largest one observed over the 9-year period of helicopter CTD surveys conducted in March. This inflow of cold and salty water from Belle Isle Strait together with the large amount of ice produced in the Gulf in the winter of 2003 caused a huge increase in the summertime thickness and volume of T < 0 °C waters (+300 %) and T < 1 °C waters (+40 %) relative to 2002. This was accompanied by a 0.65 °C drop in the cold intermediate layer minimum temperature index which is now 0.54 °C below the 1971-2000 normal conditions and the fifth coldest in 57 years. The annual mean runoff of the St. Lawrence River at Québec City was 13.4 % below normal. This led to above normal surface salinities and below normal surface layer stratification during most of 2003. In the 30-100 m layer, the 2003 temperature was colder than normal while salinity was higher than normal. In the 100-200 m layer, the 2003 temperature was colder than normal but salinity was close to normal. Finally, in the 200-300 m layer, both temperature and salinity were close to normal. The 2003 annual mean oxygen concentration in the bottom waters (≥ 300 m) of the Lower St. Lawrence Estuary (18.3% saturation) was the second lowest ever observed.

STARR, M., M. HARVEY, P.S. GALBRAITH, D. GILBERT, D. CHABOT, J.-C. THERRIAULT, 2002. Recent intrusion of Labrador Shelf waters into the Gulf of St. Lawrence and its influence on the plankton community and higher trophic levels. ICES C.M., 2002/N:16, 10 p .

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GALBRAITH, P.S., F.J. SAUCIER, N. MICHAUD, D. LEFAIVRE, R. CORRIVEAU, F. ROY, R. PIGEON, S. CANTIN, 2002. Shipborne monitoring of near-surface temperature and salinity in the Estuary and Gulf of St. Lawrence. AZMP Bull. PMZA, 2: 26-30 .

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[Abstract only available in French]
Une collaboration entre le Service Météorologique du Canada, le Ministère des Pêches et des Océans et des armateurs a permis l'installation de thermosalinographes (TSG) à bord de trois navires commerciaux et d'un navire de la Garde Côtière naviguant sur le Saint-Laurent. Ces instruments permettent le suivi en temps réel de la température des eaux près de la surface via le Système Global de Télécommunication d'Environnement Canada et l'Observatoire du Saint-Laurent. Ces données sont ensuite assimilées dans des modèles de circulation océanique permettant de prévoir l'évolution de la couverture hivernale de la glace de mer et des conditions océanographiques dans l'estuaire et le golfe du Saint-Laurent. L'installation typique d'un appareil est illustrée de même que des exemples de diffusion des données. Après seulement quelques années de fonctionnement, les appareils déployés sur les navires commerciaux font déjà découvrir de nouveaux aspects de l'océanographie du Saint-Laurent.

THERRIAULT, J.-C., P.S. GALBRAITH, M. STARR, M. HARVEY, 2002. Intrusions of Labrador shelf waters into the Gulf of St. Lawrence and their potential influence on the plankton. AZMP Bull. PMZA, 2: 12-15 .

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[Abstract only available in French]
Des données hydrographiques obtenues dans le golfe du Saint-Laurent (GSL) depuis 1996 suggèrent que les années 2001 et 2002 sont caractérisées par des intrusions particulièrement importantes d'eaux denses et froides provenant des côtes du Labrador. Ces intrusions ont significativement contribué aux températures estivales particulièrement basses de la couche intermédiaire froide (CIF) dans le GSL, en dépit de conditions hivernales relativement chaudes. Plusieurs changements dans la communauté planctonique peuvent être associés à ces intrusions d'eaux froides dans le Golfe. Le plus remarquable en 2001 est sans doute la première apparition en grande abondance de la diatomée Neodenticula seminae dans presque toutes les régions du Golfe. Ceci est très inhabituel parce que cette diatomée est normalement retrouvée dans le Pacifique Nord, et non pas dans le nord Atlantique. En raison de sa présence simultanée sur la côte du Labrador et dans le Golfe, il est fort probable que cette espèce du Pacifique ait été introduite dans le Golfe via le détroit de Belle-Isle par des processus d'advection à travers l'Arctique, en empruntant le courant du Labrador. Une autre observation qui supporte l'hypothèse d'une importante intrusion d'eaux froides dans le Golfe en 2001 est l'augmentation significative de l'abondance de l'amphipode arctique Themisto libellula. En effet, leur nombre qui passe de 0.17 ind.m-2 en septembre 2000 à 10 ind.m-2 en septembre 2001, ne peut être facilement expliqué que par cette intrusion. Ces introductions régulières d'espèces planctoniques arctiques dans le GSL ont probablement un impact significatif sur les niveaux supérieurs de la chaîne trophique tel que suggéré par la relation significative observée entre l'abondance annuelle moyenne de T. libellula et sa présence relative dans la diète de la morue entre 1996 et 2001.

GALBRAITH, P.S., 2000. Le rôle de l'hiver dans la production biologique dans le golfe du Saint-Laurent. Naturaliste can., 124(1): 59-60 .

GILBERT, D., B. PETTIGREW, D. SWAIN, P. GALBRAITH, K. DRINKWATER, 1998. Oceanographic conditions in the Gulf of St. Lawrence in 1997. Science, Stock Status Report, G4-01, 8 p .

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MINNETT, P.J., F. BIGNAMI, E. BÖHM, G. BUDÉUS, P.S. GALBRAITH, P. GUDMANDSEN, T.S. HOPKINS, R.G. INGRAM, M.A. JOHNSON, H.J. NIEBAUER, R.O. RAMSEIER, W. SCHNEIDER, 1997. A summary of the formation and seasonal progression of the northeast water polynya. J. Mar. Syst., 10: 79-85 .

GILBERT, D., A.F. VÉZINA, B. PETTIGREW, D.P. SWAIN, P.S. GALBRAITH, L. DEVINE, N. ROY, 1997. État du golfe du Saint-Laurent : conditions océanographiques en 1995. Rapp. tech. can. hydrogr. sci. océan., 191, 113 p .

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We present an overview of the oceanographic conditions in the Gulf of St. Lawrence for 1995. The highlights are that 1) winter air temperatures were near normal in the western Gulf, but were close to 2 °C below normal in the eastern Gulf; 2) the summer was warm and dry in the western Gulf; 3) the ice cover was slightly above normal, with more severe ice conditions in the northeastern Gulf than in the western Gulf; 4) the core temperature of the cold intermediate layer was colder than normal; 5) the bottom area with a temperature below 0 °C reached a record high in the southern Gulf; 6) the deep layers cooled relative to 1994, and the cooling was more intense in he 100-200 m layer (O.9 °C) than in the 200-300m layer (0.3 °C); 7) the dissolved oxygen content of the 200-300 m layer was slightly below the 1981-1995 average in the Cabot Strait and Honguedo Strait sections; 8) the distribution of chlorophyll and nitrate in the surface layer corresponded roughly with the patterns inferred from historical data, i.e. a gradient of decreasing biomass from the West and south towards the east and north that is strongly inversely correlated with salinity; 9) in Northumberland Strait, the concentrations of chlorophyll near the bottom were much higher than elsewhere.

GALBRAITH, P., D.E. KELLEY, 1996. Identifying overturns in CTD profiles. J. Atmos. Ocean. Technol., 13: 688-702 .

LAROUCHE, P., P.S. GALBRAITH, 1989. Factors affecting fast-ice consolidation in southeastern Hudson Bay, Canada. Atmos.-Ocean, 27: 367-375 .