Peter S Galbraith

Peter S Galbraith
Fisheries and Oceans Canada | DFO · Maurice Lamontagne Institute (MLI)

Ph.D.

About

128
Publications
31,631
Reads
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2,212
Citations
Citations since 2017
30 Research Items
1068 Citations
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
Introduction
Dr. Peter Galbraith is a research scientist in physical oceanography with interests in the climate of the winter water masses of the Gulf of St. Lawrence and its persisting influence on the following summer conditions, in mixing rates and turbulence, and how these interact with and affect biology. He is interested in identifying the underlying processes that drive the mixing that can lead to enhanced productivity and is an expert in the climate of the Gulf of St. Lawrence.
Additional affiliations
August 1994 - present
Fisheries and Oceans Canada
Position
  • Researcher

Publications

Publications (128)
Article
Water renewals and renewal times of the Saguenay Fjord are investigated and classified according to their intrusion depth. Renewal dynamics are controlled by a shallow sill (~20 m) at the fjord mouth, by large tides that are a distinguishing feature of the Saguenay Fjord and by large vertical mixing inside the inner basin (K~10^-4 m^2s^-1). A moori...
Article
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...
Article
Full-text available
The authors propose a scheme to test whether inversions in CTD density profiles are caused by overturning motions (from which mixing rates may be inferred) or by measurement noise. Following a common practice, possible overturning regions are found by comparing the observed profile r(z) and an imaginary profile rP (z) constructed by reordering r(z)...
Article
Full-text available
1] 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 toward warmer ice-free waters. The total volume of cold water (<À1°C) varied interannually from 10 to 15 Â 10 3 km 3 and is a...
Article
Full-text available
Bivalve growth is affected by phytoplankton quality and availability, but long-term, coastal environmental time series related to these parameters are often lacking. Therefore, it is crucial to develop methods to accurately quantify trends in phytoplankton dynamics over time. This would be especially important for the fished scallop beds in the nor...
Technical Report
Full-text available
Fisheries and Oceans Canada conducts an annual multidisciplinary survey in the Estuary and northern Gulf of St. Lawrence. The objectives of this survey are varied; assess the biodiversity of species found near the bottom; estimate the abundance of groundfish and invertebrates; assess physical and biological (phytoplankton and zooplankton) oceanogra...
Article
Full-text available
The St. Lawrence Estuary connects the Great Lakes with the Atlantic Ocean. The accepted view, based on summer conditions, is that the estuary's surface layer receives its nutrient supply from vertical mixing processes. This mixing is caused by the estuarine circulation and tides interacting with the topography at the head of the Laurentian Channel....
Preprint
Full-text available
The St. Lawrence Estuary connects the Great Lakes with the Atlantic Ocean. The accepted view, based on summer conditions, is that the Estuary's surface layer receives its nutrient supply from vertical mixing processes. This mixing is caused by the estuarine circulation and tidal-upwelling at the Head of the Laurentian Channel (HLC). During winter w...
Article
Full-text available
Uncertainties in fish tracking studies limit their integration into conservation and fisheries management plans. This is especially true for archival tagging studies that rely on geolocation models to infer fish tracks from recorded environmental variables. Hidden Markov Models (HMMs) are increasingly popular to geolocate marine fish equipped with...
Article
Full-text available
An overview of chemical and biological oceanographic conditions in the Gulf of St. Lawrence (GSL) in 2019 is presented as part of the Atlantic Zone Monitoring Program (AZMP). Data from the AZMP regional monitoring program were analyzed and described in relation to long-term means in the context of a strong warming event that began in 2010. During 2...
Article
Near-shore environments are a significant source of atmospheric methane but the size of this source is poorly constrained, particularly for fjords and fjards. This study investigated the methane emission rates and the drivers controlling the dynamics of dissolved methane in the Saguenay Fjord, a deep, stratified, and well‑oxygenated subarctic fjord...
Article
Full-text available
The St. Lawrence is a vast and complex socio-ecological system providing a wealth of services that sustain numerous economic sectors. This ecosystem is subject to significant human pressures that overlap and potentially interact with climate-driven environmental changes. Our objective in this paper was to systematically characterize the distributio...
Technical Report
Full-text available
Canadian Science Advisory Secretariat Research Document 2020/009. Preliminary results from the ecosystemic survey in August 2019 in the Estuary and northern Gulf of St. Lawrence. http://www.dfo-mpo.gc.ca/csas-sccs/Publications/ResDocs-DocRech/2020/2020_009-eng.html
Technical Report
Full-text available
Overview and synthesis of the present state of the Arctic Seas of Canada
Technical Report
Full-text available
Specific case studies in support of the main technical report 3344
Technical Report
Full-text available
Foreword This series documents the scientific basis for the evaluation of aquatic resources and ecosystems in Canada. As such, it addresses the issues of the day in the time frames required and the documents it contains are not intended as definitive statements on the subjects addressed but rather as progress reports on ongoing investigations.
Article
Krill, as forage species, play a pivotal role in marine food webs by linking lower to upper trophic levels. Despite their ecological relevance, processes affecting their physiological condition and their feeding selectivity remain not well known. Here, we hypothesize that significant spatial fluctuations of environmental conditions in a Subarctic r...
Article
An overview of chemical and biological oceanographic conditions in the Gulf of St. Lawrence (GSL) in 2018 is presented as part of the Atlantic Zone Monitoring Program (AZMP). Data from the AZMP regional monitoring program were analyzed and described in relation to long-term means in the context of a strong warming event that began in 2010. During 2...
Technical Report
Full-text available
Canadian Science Advisory Secretariat Research Document 2019/037. http://www.dfo-mpo.gc.ca/csas-sccs/Publications/ResDocs-DocRech/2019/2019_037-eng.html Abstract Fisheries and Oceans Canada conducts an annual multidisciplinary survey in the Estuary and northern Gulf of St. Lawrence. The objectives of this survey are varied: assess the biodiversity...
Article
Full-text available
An overview of chemical and biological oceanographic conditions in the Gulf of St. Lawrence (GSL) in 2017 is presented as part of the Atlantic Zone Monitoring Program (AZMP). AZMP data as well as data from regional monitoring programs are analyzed and presented in relation to long-term means in the context of a strong warming event that began in 20...
Poster
Full-text available
A regional assessment of cumulative impacts is required for the Estuary and Gulf of St. Lawrence to facilitate ecosystem based management supported by evidence. The only currently available assessment was performed at the global scale using 19 drivers of anthropogenic stressors such as fisheries and pollution. While valuable, certain datasets inclu...
Technical Report
Full-text available
Fisheries and Oceans Canada conducts an annual multidisciplinary survey in the Estuary and northern Gulf of St. Lawrence. The objectives of this survey are varied: assess the biodiversity of species found near the sea bottom, estimate the abundance of groundfish and invertebrates, assess physical and biological oceanographic conditions (phytoplankt...
Article
La circulation de renouvellement des eaux du fjord du Saguenay est examinée à la lumière de nouvelles données océanographiques. Nous avons observé une nouvelle signature de renouvellement en température et salinité occasionnée par la crue printanière, ainsi que le remplacement d’une grande partie des eaux du fjord en moins de 2 mois, confirmant le...
Poster
Full-text available
Gathering data for large scale, systematic research initiatives such as regional multi-stressor analyses can be a very challenging - not to say painful - process. On one hand, there is an overwhelming wealth of data available, while on the other hand, some required data remain largely unavailable or inaccessible. Coupled with political intricacies,...
Article
In order to define the relative vulnerability of northern shrimp (Pandalus borealis) populations to the ongoing global warming, we compared the thermal performance curves for survival and growth in the first three pelagic larval stages from three populations of the Northwest Atlantic. Egg carrying females were obtained from different regions charac...
Article
Full-text available
Characterizing migratory behaviours contributes to the sustainable management of marine fishes by resolving stock structure and identifying the timing and locations of events within fish life cycles. The migratory behaviour of Atlantic halibut (Hippoglossus hippoglossus) in the Gulf of St. Lawrence (GSL), Canada was characterized over an annual cyc...
Article
Full-text available
An overview of chemical and biological oceanographic conditions in the Gulf of St. Lawrence (GSL) in 2015 is presented as part of the Atlantic Zone Monitoring Program (AZMP). AZMP data as well as data from regional monitoring programs are analyzed and presented in relation to long-term means in the context of a strong warming event that began in 20...
Article
Full-text available
Fisheries and Oceans Canada maintains a network of scientific buoys in the St. Lawrence estuary and gulf. Among a suite of environmental parameters documented, the in-water upwelling radiance is measured using an ocean color radiometer located underneath the center of the buoy. The shadow effect from the 1.05-m-radius buoy on the measured upwelling...
Technical Report
Full-text available
Fisheries and Oceans Canada conducts an annual multidisciplinary survey in the Estuary and northern Gulf of St. Lawrence. The objectives of this survey are varied: assess the biodiversity of species found near the sea bottom, estimate the abundance of groundfish and invertebrates, assess physical and biological oceanographic conditions (phytoplankt...
Article
Full-text available
Internal solitary waves are hump-shaped, large-amplitude waves that are physically analogous to surface waves except that they propagate within the fluid, along density steps that typically characterize the layered vertical structure of lakes, oceans and the atmosphere. As do surface waves, internal solitary waves may overturn and break, and the pr...
Article
For many years, operational frameworks to guide ecosystem-based science in support of integrated marine management have been sought to address causes of marine ecosystem degradation resulting from human activities such as fisheries, industrial development, aquaculture, etc. In 2007, the Canadian Department of Fisheries and Oceans developed several...
Article
Supercritical ship internal wave wakes with $Fr=U/c_{0}\sim 4{-}12$ (where $U$ is the ship speed and $c_{0}$ is the linear internal long-wave speed) are calculated by a strongly nonlinear two-layer model in three dimensions, accounting for the complex ship geometry, and compared with field measurements. The degree of nonlinearity, defined by the sh...
Article
A three-dimensional circulation model, coupled to a Lagrangian particle drift model, is used to understand the processes leading to krill transport from the northwest Gulf of St. Lawrence (nwGSL) towards the head of the Lower St. Lawrence Estuary (LSLE), a well-known site of krill accumulation. An analysis of the circulation at the scale of the Gul...
Presentation
Full-text available
During the last decade, several habitat models were developed to predict future changes in spatial distributions of Calanus species in response to ocean warming in the north Atlantic. However, predictions made using these models cannot be quantitatively compared due to their different approaches and use of data collected with different sampling pro...
Technical Report
Full-text available
The Department of Fisheries and Oceans conducts an annual multidisciplinary survey in the Estuary and northern Gulf of St. Lawrence. The objectives of this survey are quite varied: assess the biodiversity of the species near the floor, estimate the abundance of groundfish and invertebrates, assess physical and biological oceanographic conditions (p...
Article
28 years of satellite data were used to calculate sea surface temperature (SST) climatologies covering Canada's 3 surrounding oceans and the Great Lakes. Results show the imprint of major circulation features on the spatial distribution of the SST. Together with the Gulf Stream, the Labrador Current generates a strong spatial variability of SST on...
Article
Full-text available
Fourteen years of data collected by the Atlantic Zone Monitoring Program served to model the habitat of four dominant copepod species (Calanus glacialis, Calanus hyperboreus, Calanus finmarchicus, Paracalanus sp.) on the continental shelf and slope waters in the Northwest Atlantic Ocean. Generalized additive mixed models (GAMMs) were applied to abu...
Article
Full-text available
Selon une étude publiée dans Le Naturaliste canadien, les marées de l'estuaire du Saint-Laurent ne seraient pas plus grandes aux équinoxes qu'à d'autres moments de l'année. Cette idée de marées plus grandes aux équinoxes relèverait plutôt d'une croyance populaire sans fondements théoriques, répandue même parmi la communauté scientifique. Il est dém...
Poster
Full-text available
Submesoscale baroclinic eddies in cyclostrophic balance were studied in the Saguenay fjord (Québec, Canada) using mooring data, boat-based sampling and oblique images taken from the shore, obtained in 2013 and 2015. Cyclostrophic balance implies equilibrium between the centrifugal force and the pressure gradient, with negligible Coriolis effect. Th...
Article
Full-text available
Selon une étude publiée dans Le Naturaliste canadien, les marées de l’estuaire du Saint-Laurent ne seraient pas plus grandes aux équinoxes qu’à d’autres moments de l’année. Cette idée de marées plus grandes aux équinoxes relèverait plutôt d’une croyance populaire sans fondements théoriques, répandue même parmi la communauté scientifique. Il est dém...
Article
Full-text available
An overview of chemical and biological oceanographic conditions in the Gulf of St. Lawrence (GSL) in 2014 is presented as part of the Atlantic Zone Monitoring Program (AZMP). AZMP data as well as data from regional monitoring programs are analyzed and presented in relation to long-term means in the context of a strong warming event that began in 20...
Article
Full-text available
The analysis of biomass time-series from standardized surveys, particularly comparing patterns of variation and their supposed relationship with drivers, can provide insight into how fish species and communities as a whole respond to environmental, trophic, and fishing-related drivers of change in ecosystems. Here we describe and compare the common...
Article
Full-text available
The objective of this study was to assess the effect of environmental variability on the dynamics of the Atlantic mackerel (Scomber scombrus L.) stock in the Gulf of St. Lawrence (GSL). We first described the dominant modes of physical and biological (zooplankton) variability using Principal Components Analyses of 40 variables. Two principal modes...
Article
Full-text available
Many snow crab fisheries have fluctuated widely over time in a quasi-cyclic way due to highly variable recruitment. The causes of this variability are still debated. Bottom-up processes related to climate variability may strongly affect growth and survival during early life, whereas top-down predator effects may be a major source of juvenile mortal...
Article
Full-text available
Turbulent vertical nitrate fluxes were calculated using new turbulent microstructure observations in the Lower St. Lawrence Estuary (LSLE), Canada. Two stations were compared: the head of the Laurentian Channel (HLC), where intense mixing occurs on the shallow sill that marks the upstream limit of the LSLE, and another station located about 100 km...
Article
The near-surface temperature structure in the southeastern Beaufort Sea is shown to have been largely dependent on frontal dynamics in spring 2004, which may be typical for the region. Easterly wind events generated coastal upwelling along the Cap Bathurst peninsula; a recurring event in that area. Further west, a large mesoscale anticyclone simult...
Article
Full-text available
We report on our analysis of zooplankton community structure in the western North Atlantic based on spring and fall monitoring surveys from 1999-2011 of three large marine ecosystems (LMEs; Newfoundland Shelf, Gulf of St. Lawrence and Scotian Shelf). We aimed to synthesize knowledge of the distribution of zooplankton communities and to evaluate the...
Article
Full-text available
As in many other subarctic basins, a cold intermediate layer (CIL) is found during ice-free months in the Lower St. Lawrence Estuary (LSLE), Canada. This study examines the behavior of the CIL above the sloping bottom using a high-resolution mooring deployed on the northern side of the estuary. Observations show successive swashes/backwashes of the...
Article
Full-text available
An overview of physical oceanographic conditions in the Gulf of St. Lawrence in 2014 is presented as part of the Atlantic Zone Monitoring Program (AZMP). AZMP data as well as data from regional monitoring programs are analysed and presented in relation to long-term means. The annual average freshwater runoff of the St. Lawrence River measured at Qu...
Article
Full-text available
Summary Surface temperatures averaged over all ice-free months were at record highs in the St. Lawrence Estuary and were above normal in all but one region across the zone. August surface temperatures were at record highs in 7 of 12 regions in the zone. Surface temperatures in Division 4X‑east and Gulf of Maine‑Bay of Fundy were at record highs fo...
Conference Paper
Snow crab landings in the Gulf of St. Lawrence (eastern Canada) have fluctuated greatly since the beginning of the fishery due to highly variable recruitment. This variability is established early in life and may result from bottom-up processes related to climate variation, top-down effects and/or population-intrinsic processes. We explored how cli...