Véronique Lesage

• Doctor of Philosophy
• Researcher at Fisheries and Oceans Canada

Blue whales Balaenoptera musculus occur seasonally in the St. Lawrence Estuary, Canada, where they spend most of their time foraging. Their recurrent presence has stimulated the development of a large whale-watching industry. Here, we examine the effect of vessel distance on blue whale foraging behaviour by measuring changes in surface and diving p...

The blue whale Balaenopterus musculus is a wide-ranging cetacean that can be found in all oceans. In the North Atlantic, little is known about blue whale distribution and genetic structure, or about the interconnections between areas of aggregations in Icelandic waters, the Azores, Northwest Africa, and the Northwest Atlantic. Seasonal movements of...

Noise can cause marine mammals to interrupt their feeding, alter their vocalizations, or leave important habitat, among other behavioural responses. The current North American paradigm for regulating activities that may result in behavioural responses identifies received levels (RL) of sound at which individuals are predicted to display significant...

Integrated population models combine data from several sources into a single model to allow the simultaneous estimation of demographic parameters and the prediction of population trajectories. They are especially useful when survey data alone are insufficient to estimate precise vital rates and abundance, and to understand mechanisms of population...

Accurate predictions of predator behavior remain elusive in natural settings. Optimal foraging theory predicts that breath-hold divers should adjust time allocation within their dives to the distance separating prey from the surface. Quantitative tests of these models have been hampered by the difficulty of documenting underwater feeding behavior a...

Changes in trophodynamics may affect trophic niche both at the individual and population levels. Using stable isotope ratios, we showed how contrasting oceanographic and trophic conditions in 1997–2003 and 2015–2020 have altered the diet and degree of individual specialization of St. Lawrence Estuary beluga (Delphinapterus leucas). The trophic nich...

The St. Lawrence Estuary (SLE) beluga (Delphinapterus leucas) population in Canada is Endangered, and endocrine disrupting contaminants, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and other halogenated flame retardants, have been identified as a threat to the recovery of this population. Here, potential impact...

Understanding the causes of mortality for a declining species is essential for developing effective conservation and management strategies, particularly when anthropogenic activities are the primary threat. Using a competing hazards framework allows for robust estimation of the cause‐specific variation in risk that may exist across multiple dimensi...

Effective conservation strategies inherently depend on preserving populations, which in turn requires accurate tools for their detection. Beluga whales (Delphinapterus leucas) inhabit the circumpolar Arctic and form discrete summer aggregations. Previous genetic studies using mitochondrial and microsatellite loci have delineated distinct population...

Carcasses of endangered beluga whales Delphinapterus leucas from the St. Lawrence Estuary, Canada, have been examined consistently since 1983 to determine causes of death. The objective of this study is to compare the nutritional condition of belugas that died of different causes. Previously published categories of death were refined to discriminat...

Interindividual variability in habitat preferences affect local abundance and residency times. Within a population range, this can lead to sectors having a continuous flow of unique individuals, with others being used by the same set of resident individuals. These patterns of habitat use by individuals, referred to here as individual spatial mixing...

Stable carbon (δ ¹³ C) and nitrogen (δ ¹⁵ N) isotope ratios are widely used in marine food web and habitat use studies. However, lipids are naturally depleted in ¹³ C relative to proteins and are variable in content, biasing δ ¹³ C of bulk samples, with consequences for the accuracy of conclusions. This issue can be resolved either by extracting li...

Fin whales, Balenoptera physalus, are capital breeders, having the potential to separate breeding and feeding both spatially and temporally. Fin whales occur throughout the Northwest Atlantic, but stock structure and seasonal movements remain unclear. By deploying satellite transmitters on 28 individuals, we examine movement patterns within and bey...

The recent steep decline of critically endangered North Atlantic right whales ( Eubalaena glacialis ) can be attributed to high mortality combined with low reproduction. While the former is a clear result of anthropogenic activity, the latter involves more complexity. Evidence suggests that both short-term fluctuations in prey availability and long...

Abundance estimation of wildlife populations is frequently derived from systematic survey data. Accuracy and precision of estimates, however, depend on the number of replicate surveys, and on adjustments made for animals unavailable to (availability bias), or available but undetected (perception bias) by observers. This study offers a comprehensive...

A network of 10 passive acoustics monitoring stations is used to examine patterns of habitat use at diel and tidal timescales by St. Lawrence Estuary beluga during summer 2018 and 2019. An occurrence index of vocal activity within the preferred frequency band of communications for belugas is used as a proxy for presence at the stations. Diel and ti...

Documenting long-term changes in the trophic structure of food webs and how species respond to these changes is essential to forecast their vulnerability and resilience to environmental stressors. Over the past decades, the St. Lawrence marine ecosystem (Canada) has experienced major changes in its physical, chemical, and biological conditions from...

Lipids are naturally depleted in ¹³ C isotope in relation to its C sources, causing a bias in δ ¹³ C in bulk samples that varies with lipid content. Failure to take this issue into account results in inaccurate conclusions in food web and habitat use studies. Two approaches to resolve this issue are 1) to extract lipids from samples prior to measur...

Understanding the causes of mortality for a declining species is essential for developing effective conservation and management strategies, particularly when anthropogenic activities are the primary threat. Using a competing hazards framework allows for robust estimation of the cause-specific variation that may exist across multiple dimensions, suc...

The North Atlantic right whale (Eubalaena glacialis) is among the most endangered whale species in the world and has been in decline since 2010. Considerable effort is directed toward its recovery by striving to remove threats. In this report, we describe the development of a population viability analysis for right whales that is designed to assess...

Beluga (Delphinapterus leucas) from the St. Lawrence Estuary, Canada, have been declining since the early 2000s, suggesting recruitment issues as a result of low fecundity, abnormal abortion rates or poor calf or juvenile survival. Pregnancy is difficult to observe in cetaceans, making the ground truthing of pregnancy estimates in wild individuals...

The Harbour porpoise (Phocoena phocoena) is a highly mobile cetacean species primarily occurring in coastal and shelf waters across the Northern hemisphere. It inhabits heterogeneous seascapes broadly varying in salinity and temperature. Here, we produced 74 whole genomes at intermediate coverage to study Harbour porpoise's evolutionary history and...

The spatial-temporal distribution pattern of St. Lawrence Estuary (SLE) beluga is examined with a passive acoustic monitoring network of 13 stations from June 2018 to October 2021. A beluga calling index, correlated with beluga density, is used as a proxy for habitat use by the population at weekly, monthly, and yearly scales. The seasonal pattern...

Toxoplasmosis is a parasitic disease caused by the zoonotic protozoan Toxoplasma gondii. This parasite, whose definitive hosts are Felidae, including domestic cats, can cause fatal systemic infections in juveniles and adults of various animal species. During primary in-utero infection, T. gondii can, among other things, cause embryonic resorptions,...

The St. Lawrence Estuary (SLE) beluga whale (Delphinapterus leucas) population in Canada is endangered. It has been postulated that exposure to elevated concentrations of polychlorinated biphenyls (PCBs), chlorinated pesticides, polybrominated diphenyl ethers (PBDEs), and emerging halogenated flame retardants (HFR) might be contributing to the decl...

Very high levels of industrial contaminants in St. Lawrence Estuary (SLE) beluga whales represent one of the major threats to this population classified as endangered under the Species at Risk Act in Canada. Elevated concentrations of short-chained chlorinated paraffins (SCCPs) were recently reported in blubber of adult male SLE belugas. SCCPs are...

Highly polymorphic single tandem repeat loci (STR, also known as microsatellite loci) remain a familiar, cost efficient class of markers for genetic analyses in ecology, behavior and conservation. We characterize a new universal set of ten STR loci (from 28 potential candidate loci) in seven baleen whale species, which are optimized for PCR amplifi...

The incidental catch of harbour porpoises (Phocoena phocoena) in the gillnet fishery of the Estuary and Gulf of St. Lawrence, Canada, was examined using: (1) questionnaires mailed to fishermen inquiring about bycatches in 2000 and 2001 (n=2,277 or 44% of the fishermen with valid licenses); and (2) using data from an at-sea observer programme and se...

Very high levels of industrial contaminants in St. Lawrence Estuary (SLE) beluga whales represent one of the major threats to this population classified as endangered under the Species at Risk Act in Canada. Elevated concentrations of short-chained chlorinated paraffins (SCCPs) were recently reported in blubber of adult male SLE belugas. Recent reg...

The Harbour porpoise (Phocoena phocoena) is a highly mobile cetacean species which primarily occurs in coastal and shelf waters across the Northern hemisphere. It inhabits heterogeneous seascapes that vary broadly in salinity and temperature. Here we produced 74 whole genomes at intermediate coverage to study Harbour porpoise’s evolutionary history...

Very high levels of industrial contaminants in St. Lawrence Estuary (SLE) beluga whales represent one of the major threats to this population classified as endangered under the Species at Risk Act in Canada. Elevated concentrations of short-chained chlorinated paraffins (SCCPs) were recently reported in blubber of adult male SLE belugas. Recent reg...

Biologging tags are a key enabling tool for investigating cetacean behavior and locomotion in their natural habitat. Identifying and then parameterizing gait from movement sensor data is critical for these investigations, but how best to characterize gait from tag data remains an open question. Further, the location and orientation of a tag on an a...

Estimating the impacts of anthropogenic disturbances requires an understanding of the habitat‐use patterns of individuals within a population. This is especially the case when disturbances are localized within a population's spatial range, as variation in habitat use within a population can drastically alter the distribution of impacts. Here, we il...

Anthropogenic underwater noise has been identified as a potentially serious stressor for the critically endangered North Atlantic right whale (NARW). The Government of Canada is undertaking steps to better characterize the noise sources of most concern and their associated impacts, but there is currently an insufficient understanding of which noise...

Biologging tags are a key enabling tool for investigating cetacean behavior and locomotion in their natural habitat. Identifying and then parameterizing gait from movement sensor data is critical for these investigations. But how best to characterize gait from tag data remains an open question. Further, the location and orientation of the tag on an...

Decades after a ban on hunting, and despite focused management interventions, the endangered St. Lawrence Estuary (SLE) beluga (Delphinapterus leucas) population has failed to recover. We applied a population viability analysis to simulate the responses of the SLE beluga population across a wide range of variability and uncertainty under current an...

Vessel underwater noise (VUN) is one of the main threats to the recovery of the endangered St. Lawrence Estuary Beluga population (SLEB). The 1% yearly population decline indicates that the cumulative threats are already beyond sustainable limits for the SLEB. However, a potential threefold increase in shipping traffic is expected within its critic...

Until 2012, the St. Lawrence Estuary beluga population was considered stable with about 1100 individuals. An abnormally high number of calves reported dead that year triggered a population status reassessment. This review article summarizes the findings from this reassessment and various studies subsequent to it and provides an updated analysis of...

This study sought to estimate the effect of an anthropogenic and climate-driven change in prey availability on the degree of individual and population specialization of a large marine predator, the fin whale ( Balaenoptera physalus ). We examined skin biopsies from 99 fin whales sampled in the St. Lawrence Estuary (Canada) over a nine year period (...

Description This study sought to estimate the effect of an anthropogenic and climate-driven change in prey availability on the degree of individual and population specialization of a large marine predator, the fin whale (Balaenoptera physalus) in the estuary and the gulf of St. Lawrence (eastern Canada). Specifically, we here examine the trophic ni...

Noise and anthropogenic disturbances from vessel traffic are an important threat to the recovery of the endangered St. Lawrence Estuary (SLE) beluga population. The consequences of acoustic masking could be particularly adverse in the case of critical vocalizations that maintain contact between mothers and their dependent but mobile calves. This st...

Abstract An understanding of habitat use and connectivity is key to preserving wildlife habitat integrity. In this study, we present an innovative approach to habitat connectivity and quantitative assessment of their use that is applicable to any terrestrial or aquatic species. Specifically, we aimed at estimating the proportion of the St. Lawrence...

Elusive wildlife are challenging to study, manage, or conserve, as the difficulty of obtaining specimens or conducting direct observations leads to major data deficiencies. Specimens of opportunity, such as salvaged carcasses or museum specimens, are a valuable source of fundamental biological and ecological information on data deficient, elusive s...

Elusive wildlife are challenging to study, manage, or conserve, as the difficulty of obtaining specimens or conducting direct observations leads to major data deficiencies. Specimens of opportunity, such as salvaged carcasses or museum specimens, are a valuable source of fundamental biological and ecological information on data deficient, elusive s...

Photo identification of individuals within a population is a common data source that is becoming more common given technological advances and the use of computer vision and machine learning to re-identify individuals. These data are collected through hand-held cameras, drones, and camera traps, and often come with biases in terms of sampling effort...

Climate-induced changes in calanoid copepod ( Calanus spp.) availability in traditional feeding areas might explain why a large proportion of the North Atlantic right whale Eubalaena glacialis population has fed in the Gulf of St. Lawrence (Canada) in recent years. However, little is known about the distribution of copepods in the gulf, and whether...

The endangered St. Lawrence Estuary (SLE) beluga population is declining and has shown no sign of recovery over the past decades despite several protective measures. Changes in the availability of food resources and exposure to organohalogen contaminants have been suggested as potential factors limiting the recovery of this population. Studies on S...

The North Atlantic Right Whale (NARW) is an endangered species that feeds primarily on Calanus finmarchicus in their traditional feeding areas in the western North Atlantic. In recent years, the Gulf of St. Lawrence (GSL) was identified as an important feeding ground for this population. In this region, the large and lipid-rich C. finmarchicus, C....

The North Atlantic right whale (Eubalaena glacialis, NARW) is an endangered cetacean which faces population decline from anthropogenic activities. Climate change may also be adding pressure on population recovery by shifting distribution of their preferred prey, Calanus copepods. The Gulf of St. Lawrence (GSL) in eastern Canada has been used as a f...

The monodontids—narwhals, Monodon monoceros, and belugas, Delphinapterus leucas—are found in much of the Arctic and in some subarctic areas. They are hunted by indigenous subsistence users. In the past, some populations were substantially reduced by commercial hunting and culling; more recently, some populations have declined due to uncontrolled su...

Blue whale survival and fitness are highly contingent on successful food intake during an intense feeding season. Factors affecting time spent at the surface or at depth in a prey patch are likely to alter foraging effort, net energy gain, and fitness. We specifically examined the energetic consequences of a demonstrated reduction in dive duration...

Ecosystems and community structure fluctuate over time as a result of natural and anthropogenic factors that may affect prey availability and population dynamics. Most of what we know about St. Lawrence Estuary (SLE) Beluga (Delphinapterus leucas) diet comes from stomach contents collected 80 years ago mainly from a hunting site that Beluga no long...

The endangered beluga (Delphinapterus leucas) population residing in the St. Lawrence Estuary (SLE; Eastern Canada) is declining. The elevated tissue concentrations of a wide range of organohalogen contaminants might play a role in the non-recovery of this whale population. Organohalogens have been reported to impair the regulation of several metab...

This study aimed at identifying potentially suitable foraging habitats for the North Atlantic right whale (NARW; Eubalaena glacialis) in the Gulf of St Lawrence (GSL), on the Scotian Shelf (SS) and in the Bay of Fundy (BoF), Canada, based on the distribution densities of their main prey, Calanus copepod species. More than 4800 historical Calanus sp...

Foraging efficiency (FE) is determined by the ratio of energy intake to energy expen- diture and represents a metric for estimating the capacity to store energy. Blue whales Bal- aenoptera musculus rely mostly on stored energy reserves for reproduction. They feed almost exclusively on krill, which vary in density and abundance both spatially and te...

Elevated concentrations of persistent organic pollutants (POPs) and emerging halogenated flame retardants (HFRs) have been reported in tissues of the endangered St. Lawrence Estuary (Canada) beluga population as well as in minke whales visiting that same feeding area. This study examined the linkages between blubber concentrations of POPs and emerg...

Part of the western Atlantic population of leatherback turtles (Dermochelys coriacea (Vandelli, 1761)) forage in Canadian waters, where high-use areas have been identified using satellite telemetry and opportunistic sightings. Here, we use sightings of leatherback turtles and ocean sunfish (Mola mola (Linnaeus, 1758)) obtained during a systematic l...

Lethal collisions with ships are limiting the recovery of several at-risk whale species worldwide. In the St. Lawrence Estuary (Quebec, Canada), the endangered blue whale and of special concern fin whale are among the migratory species subject to collisions with large ships. In 2011, a working group composed of representatives from the maritime ind...

Composition of the working group. (DOCX)

Speed through water: Description and accuracy. (DOCX)

Step-by-step procedure to compute the effectiveness of the voluntary conservation measures. (DOCX)

Overall slow-down efforts in the speed reduction area (SRA). (DOCX)

The profiling of reproductive and stress steroid hormones in cetaceans provides vital information for both conservation and management decisions. This is especially the case for endangered species, such as the western gray whale (Eschrichtius robustus) subpopulation, as stated by the IWC scientific community. We previously validated reproductive ho...

Studies of the behaviour of diving animals usually focus on either individual dives or surface group activities, but these complementary observations are seldom combined in the same study. We here study the summer (June–October) behaviour of St. Lawrence Estuary belugas (Delphinapterus leucas (Pallas, 1776)) by combining fine-scale individual divin...

Les organismes vivant dans le fleuve et l’estuaire du Saint-Laurent sont exposés aux rejets urbains et agricoles des grands bassins versants situés en amont de ces écosystèmes. Une étude récente de notre laboratoire a démontré que plusieurs retardateurs de flamme halogénés (c.à.d., PBDE et composés émergents) sont détectés dans le gras de bélugas d...

An exponential level increase of the ubiquitous halogenated flame retardant (HFR) class polybrominated diphenyl ether (PBDE) has been documented during the 1990s in endangered belugas (Delphinapterus leucas) from the St. Lawrence Estuary (SLE), Eastern Canada. The recent worldwide bans and regulations of PBDE mixtures led to their replacement by al...

The St. Lawrence Estuary (“SLE”) population of beluga (Delphinapterus leucas) was depleted by hunting. The population failed to increase in numbers at the rate one would expect after cessation of hunting. We conducted a population viability analysis (“PVA”) to quantify factors that most likely limit recovery of SLE beluga. The main threats consider...

2011/086 also available at http://www.dfo-mpo.gc.ca/csas-sccs/Publications/ResDocs-DocRech/2011/2011_086-eng.html

The objective of this study was to describe the spatial distribution of krill in eastern Canadian waters using a statistical modelling approach in support of the identification of important habitat for the western North Atlantic (WNA) blue whale (Balaenoptera musculus). Generalized Additive Models (GAMs) were constructed from krill biomass data obt...

We present preliminary results of a project aimed at identifying new potential foraging habitats for the North Atlantic Right Whale (Eubalaena glacialis) (NARW) in the Gulf of St. Lawrence (GSL) and on the eastern Scotian Shelf (eSS). More than 4800 stations sampled during the 1979-2012 period were used to assemble a georeferenced dataset of Calanu...

Depuis plusieurs années, le concept d’approche écosystémique est avancé mondialement comme une solution possible aux problématiques de gestion liées à la détérioration des écosystèmes marins et de leurs ressources découlant de l’activité humaine, incluant les pêches, le développement industriel, l’aquaculture, etc. Au Canada, le ministère des Pêche...

Situé en aval de plusieurs grandes villes, l’estuaire du Saint-Laurent reçoit d’importantes quantités de retardateurs de flamme halogénés (RFH). Le béluga, espèce résidente de l’estuaire, ainsi que plusieurs espèces de baleines qui viennent s’y alimenter chaque été, sont exposés à ces contaminants. Notre objectif était d’étudier les tendances tempo...

Located downstream of a number of large cities, the St. Lawrence Estuary (Eastern Canada) has over the years become a highly contaminated area by halogenated flame retardants (HFRs). Each summer, several whale species migrate into the St. Lawrence Estuary for feeding. Due to their high trophic level, certain tooth and baleen whales are highly expos...

In the western North Atlantic (wNA), the Atlantic white-sided dolphin (Lagenorhynchus acutus) inhabits waters ranging from central West Greenland south to North Carolina along the US East Coast and is currently delineated as a single management stock. However, evidence based on sightings, strandings, and incidental fisheries takes suggests the pres...

The Gulf of St. Lawrence (GSL) is a feeding ground for several baleen whale species from the North Atlantic, providing them with an abundant supply of krill during their seasonal presence. Krill aggregations are found along the abrupt topography formed by the deep channels, but the dynamics of krill aggregations have not yet been characterized at t...

Le fleuve Saint-Laurent est un écosystème unique reconnu mondialement pour sa diversification et sa grande richesse biologique. Depuis plusieurs décennies, cette diversité est menacée à cause d’un fort développement industriel et démographique, provoquant le déversement d’énormes quantités de produits chimiques. Chaque année, de nombreux mammifères...

Data about age-specific survival and mortality rate, as well as life history parameters are essential for studying population demography. However, noninvasive methods for ageing free-ranging marine mammals are generally lacking. Recently, a few studies have highlighted the potential of using fatty acid (FA) composition in blubber biopsy samples to...

In Canada, interest in a potential new krill source focusses on the evaluation of biochemical composition of northern and arctic krill for nutraceutical, cosmetic and pharmaceutical industries. Our prime objective is to examine the ecological resilience of the krill stocks in the St. Lawrence system prior to human exploitation. Krill stocks must co...

Stable isotope analyses of C and N (d 13 C and d 15 N) provide an integrative way to assess dietary and habitat preferences of marine organisms. This approach has been increasingly used over the last decade to investigate these questions in apex marine predators such as marine mammals (e.g., Lesage et al. 2001, Das et al. 2003, Zhao et al. 2004, Pi...