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DONIOL-VALCROZE, T., M.O. HAMMILL, VÉRONIQUE LESAGE, 2011. Information on abundance and harvest of eastern Hudson Bay beluga (Delphinapterus leucas) ; Information sur labondance et les prélèvements de bélugas de lest de la Baie dHudson (Delphinapterus leucas). DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2010/121, 31 p .
Subsistence harvest of beluga whales by Nunavik communities is directed towards a mixture of two populations: the Western Hudson Bay stock (WHB) and the depleted Eastern Hudson Bay stock (EHB). The 2010 harvest consisted of 45 beluga killed near Sanikiluaq (Belcher Islands), 16 in the eastern Hudson Bay area, 15 in Ungava Bay, 146 in Hudson Strait in the spring and 58 in the fall. Since 2009, it is assumed based on genetic data that all animals killed in EHB, 10 % of those killed in the spring and summer in Hudson Strait, and 20 % of those killed in Ungava Bay and during the fall in Hudson Strait are EHB beluga. It is also assumed that 12 % of beluga killed by Sanikiluaq hunters belong to the EHB stock. Using these proportions, the 2010 harvest is equivalent to 51 EHB beluga. A population model incorporating updated information on harvest statistics and stock composition was fitted to aerial survey estimates using Bayesian methods, and resulted in a 1985 population estimate of 4,118 animals with a 95 % Credible Interval (CI) of 2,219–8765. The lowest abundance point was estimated at 2,977 (95 % CI 1,970–4,674) for the year 2001. The model estimated a population in 2010 of 3,034 individuals (95 % CI 1,390–6,181). At current harvest levels, the population has probably remained stable over the last few years. The model estimated struck-and-loss at 56 % (95 % CI 22–144 %) and growth rate at 2.7 % per year (95 % CI -3.1–8.5 %). Removing 50 EHB animals in future harvests has a 50 % probability of causing a decline in the population, while lower harvests would likely allow some recovery. Limiting the harvest of EHB animals to 10 individuals reduced the probability of decline to 25 %. Conversely, a harvest of 100 EHB whales has a 75 % probability of leading to population decline. No harvest scenario could produce a 5 % probability of decline, since the probability of decline in absence of harvest was 18 %. However, the number of animals that can be harvested without causing a decline in the EHB beluga population will depend on how catches are distributed between Eastern Hudson Bay, Ungava Bay and Hudson Strait, as well as the proportion of spring/summer vs. fall catches in Hudson Strait. Analyses of the beluga harvest in Hudson Strait, combining age to probabilistic information on stock of origin determined from mitochondrial DNA, showed that the age structure of EHB beluga was strongly skewed towards younger individuals and contained less older individuals compared to the non-EHB whales. These results might indicate a disproportional catch of younger EHB animals, significant harvesting pressure on the EHB stock or both.
DONIOL-VALCROZE, T., V. LESAGE, J. GIARD, R. MICHAUD, 2011. Optimal foraging theory predicts diving and feeling strategies of the largest marine predator. Behav. Ecol., 22(4): 880-888 .
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 and the lack of systems, experimental or natural, in which prey depth varies over a large range. We tested these predictions on blue whales (Balaenoptera musculus), which track the diel vertical migration of their prey. A model using simple allometric arguments successfully predicted diving behavior measured with data loggers. Foraging times within each dive increased to compensate longer transit times and optimize resource acquisition. Shallow dives were short and yielded the highest feeding rates, explaining why feeding activity was more intense at night. An optimal framework thus provides powerful tools to predict the behavior of free-ranging marine predators and inform conservation studies.©2011 Oxford University Press
ANDERWALD, P., A.K. DANIELSDOTTIR, T. HAUG, F. LARSEN, V. LESAGE, R.J. REID, G.A. VIKINGSSON, A.R. HOELZEL, 2011. Possible cryptic stock structure for minke whales in the North Atlantic : implications for conservation and management. Biol. Conser., 44: 2479-2489 .
The minke whale is the last of the great whale species to be hunted in significant numbers. Effective management must include an understanding of how genetic diversity is divided and distributed among putative local populations, and as for many migratory species, this is complicated for the minke whale by large-scale seasonal movement among geographic regions. The problem is that the geographic identity of breeding populations is not known, and instead these whales are predictably found and hunted where different breeding stocks may mix on seasonal feeding grounds. Here we use microsatellite DNA and mtDNA markers to investigate minke whale population structure across the species range in the North Atlantic. We found no evidence of geographic structure comparing putative populations in recognized management areas, though some limited structure had been indicated in earlier studies. However, using individual genotypes and likelihood assignment methods, we identified two putative cryptic stocks distributed across the North Atlantic in similar proportions in different regions. Some differences in the proportional representation of these populations may explain some of the apparent differentiation between regions detected previously. The implication would be that minke whales range extensively across the North Atlantic seasonally, but segregate to some extent on at least two breeding grounds. This means that established stock boundaries in the North Atlantic, currently used for management, should be re-considered to ensure the effective conservation of genetic diversity.©2011 Elsevier Ltd.
POMERLEAU, C., G. WINKLER, A.R. SASTRI, R.J. NELSON, S. VAGLE, V. LESAGE, S.H. FERGUSON, 2011. Spatial patterns in zooplankton communities across the eastern Canadian sub-Arctic and Arctic waters : Insights from stable carbon (δ 13C) and nitrogen (δ15N) isotope ratios. J. Plankton Res., 33(12): 1779-1792 .
This study defined the status quo of biogeographic domains and examined spatial patterns of stable isotopes (Sis) of carbon and nitrogen in relation to biophysical groupings to gain greater insight into how mesozooplankton may respond to continuous environmental change in the Canadian Arctic and sub-Arctic regions. Mesozooplankton communities were sampled during the summer of 2007 along a transect from Belle-Isle Strait, NFL, to Kugluktuk, NU (Canada), and during the early autumn of 2009 along a transect extending from Pelly Bay to Hall Beach, NU. Five broad water mass types corresponded to geographical regions. In general, we found relationships between water mass and species composition; however, this relationship was not always straightforward. Mesozooplankton community composition varied along the transect, revealing eight species assemblages. Calanus finmarchicus was abundant in the warmer and saltier Atlantic waters of the Labrador Sea, whereas Calanus hyperboreus, Calanus glacialis and Metridia longa were most abundant in the cold Arctic waters of Central Baffin Bay and in the eastern portion of the Canadian Arctic Archipelago. Nitrogen and carbon SI analysis revealed that δ15N (but not δ13C) varied spatially for C. glacialis, C. hyperboreus, Paraeuchaeta spp. And Themisto libellula. δ15N values were less enriched in Davis Strait and more enriched in the Gulf of Boothia. Seasonality, oceanic fronts and changes in the trophic structure at the base of each regional food web may explain some of the observed variability. This study represents the first broad-scale characterization of the composition and isotopic signatures for mesozooplankton communities ranging from the sub-Arctic Atlantic to the western Central Arctic Archipelago. Our study provides a baseline of the zooplankton community for monitoring species biogeographical range.©2011 Oxford University Press
A better understanding of animal movements is of crucial importance for investigating numerous ecological issues. Developments in bio-logging technologies largely contributed to the observation and recording of animal displacements. Recently, several devices were developed to track animals in a three-dimensional space. However, given the larger number of variables, these advances generated new analytical problems and currently, few methods exist to analyse 3-D movements. In this study,wepresent a new technique, the Spherical First Passage Time (SFPT), to determine the scale of search behaviour in a volume. Building on the development of the First Passage Time (FPT) approach, SFPT measures the time required to cross a sphere along a 3-D path.Weused simulations as they provide an opportunity to better understand processes involved in a system. Moreover, they offer the advantage of considerably increasing sample size in cases where empiric data remain scarce. However, in order to be more realistic, simulations were constrained within the physiological and behavioural features inherent to a diving animal, in this case beluga whales. First, we modelled three-dimensional movements as a correlated random walk for which the vertical and horizontal dimensions were considered simultaneously. One restricted search event was included in each simulation. Spatial scales obtained with the SFPT approach were compared to those obtained from the classical FPT analysis over the corresponding horizontal path. Results indicate a significant difference between the two approaches, suggesting that, in most cases, an approach in 2-D misrepresents spatial scale of search behaviour occurring in 3-D. Although we tested the SFPT with the example of a diving marine mammal, we argue that this method is applicable for all animals moving in a three-dimensional space.© 2010 Elsevier B.V.
LESAGE, V., Y. MORIN, E. RIOUX, C. POMERLEAU, S.H. FERGUSON, E. PELLETIER, 2010. Stable isotopes and trace elements as indicators of diet and habitat use in cetaceans : predicting errors related to preservation, lipid extraction, and lipid normalization. Mar. Ecol. Prog. Ser., 419: 249-265 .
Accurately predicting errors related to preservation, lipid extraction, and lipid normalization on chemical tracers would enable the use of archived samples in long-term studies of trophic ecology and habitat use of aquatic species. We determined whether stable carbon and nitrogen isotope ratios and concentrations of 14 trace elements can be accurately predicted from dimethyl sulfoxide (DMSO)-preserved mammal skin, which would provide equivalent estimates to that from unpreserved tissue. We tested 3 lipid-correction approaches for applicability to cetacean skin, a largely unexplored taxon and tissue, and provide a model for evaluating impacts of errors from lipid extraction or normalization on diet composition estimated using isotopic mixing models. DMSO had unpredictable effects on trace element concentrations, rendering DMSO-preserved samples inefficient for retrospective studies. However, lipid extraction and DMSO preservation resulted in predictable and similar, although not identical, effects on isotopic signatures across 4 cetacean species with different skin structure and thickness, making correction for these effects a potentially viable alternative to lipid and DMSO extraction. Generally, lipid-normalization models were reliable when applied to cetacean skin, as errors were similar to those from other species or tissues. Because model fit generally improved with data specificity, developing tissue- and species-specific parameters and equations is probably more important than model choice, although the mass-balance model was considered the most robust across aquatic vertebrates and tissues. The effects of errors associated with the various treatments and lipid normalization on isotopic mixing results increased as the isotopic distance among prey sources decreased, suggesting that empirical corrections as an alternative to d13C determination from lipid-extracted duplicate samples need to be evaluated a priori relative to study objectives and anticipated results.©2010 Inter-Research
ARCHAMBAULT, P., P.V.R. SNELGROVE, J.A.D. FISHER, J.M. GAGNON, D.J. GARBARY, M. HARVEY, E.L. KENCHINGTON, V. LESAGE, M. LEVESQUE, C. LOVEJOY, D.L. MACKAS, C.W. MCKINDSEY, J.R. NELSON, P. PEPIN, L. PICHE, M. POULIN, 2010. From Sea to Sea: Canada's Three Oceans of biodiversity. PLoS ONE, 5(8): 1-26 .
Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada's three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada's three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada's natural heritage.©2010PLoS one.
DUFRESNE, M.M., H. FROUIN, S. PILLET, V. LESAGE, S. DE GUISE, M. FOURNIER, 2010. Comparative sensitivity of Harbour and Grey Seals to several environmental contaminants using in vitro exposure. Mar. Pollut. Bull., 60(3): 344-349 .
In this study, we investigated the effects of cadmium chloride (CdCl2), mercury chloride (HgCl2), methylmercury chloride (CH3HgCl), and PCBs on lymphocyte proliferation in phocids. PBMCs isolated from harbour and grey seals were exposed in vitro to varying concentrations of contaminants. A reduction of viability occurred when cells were exposed to 10-4 M HgCl2 or CH3HgCl or to 50 ppm of Aroclor 1254. In both grey and harbour seals, T-lymphocyte proliferation was suppressed when their cells were incubated with 5 × 10-5 M CdCl2 or 10-4 M HgCl2. An inhibition of proliferation occurred with CH3HgCl from 10-6 M in grey seals and from 10-5 M in harbour seals. In grey seals, Aroclor 1254 reduced lymphocyte proliferation at 15 ppm. In both harbour and grey seals, CH3HgCl was ten times more immunotoxic that HgCl2. From IC50, chemicals were ranked in terms of toxicity as followed: CH3HgCl > CdCl2 > HgCl2 > Aroclor 1254.©2009 Elsevier Ltd.
HAMMILL, M., V. LESAGE, J.-F. GOSSELIN, 2009. Évaluation du stock de bélugas du nord du Québec (Nunavik) (Delphinapterus leucas). MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2009/016, 13 p .
LEWIS, A.E., M.O. HAMMILL, M. POWER, D.W. DOIDGE, V. LESAGE, 2009. Movement and aggregation of eastern Hudson Bay beluga whales (Delphinapterus leucas) : a comparison of patterns found through satellite telemetry and Nunavik traditional ecological knowledge. Arctic, 62(1): 13-24 .
Traditional Ecological Knowledge (TEK) consists of the collective knowledge, experience, and values of subsistence communities, while Western science relies on hypothesis testing to obtain information on natural processes. Both approaches provide important ecological information, but few studies have directly compared the two. We compared information on movements and aggregation of beluga whales obtained from TEK interview records (n=3253) and satellite telemetry records of 30 whales tagged in eastern Hudson Bay, Canada, using geographic information system (GIS) approaches that allowed common formatting of the data sets. Estuarine centres of aggregation in the summer were evident in both data sets. The intensive use of offshore areas seen in the telemetry data, where 76 % of the locations were more than 15 km from mainland Quebec, was not evident in the TEK data, where only 17 % of the records indicated offshore locations. Morisita's index of similarity indicated that TEK and telemetry data distributions varied with season, with the highest similarity in winter (0.74). Location and movement data from the telemetry study were limited by small sample size and short tag deployment times, while TEK data were biased by spatial coverage and coastal travel habits. Although the two data sets can provide complementary information, both suffer from weaknesses that need to be acknowledged when these data are adapted for use in resource management.©2009 The Arctic Institute of North America
HAMMILL, M., V. LESAGE, J.-F. GOSSELIN, 2009. Évaluation du stock de béluga du nord du Québec (Nunavik) (Delphinapterus leucas). MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2009/076, 8 p .
LESAGE, V., 2009. Avis sur la désignation de l'habitat essentiel des bélugas du Saint-Laurent (Delphinapterus leucas). MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2009/070, 9 p .
HAMMILL, M., V. LESAGE, J.-F. GOSSELIN, 2009. Stock assessment of Northern Quebec (Nunavik) Beluga (Delphinapterus leucas). DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2009/076, 7 p .
LESAGE, V., 2009. Advice relevant to the identification of critical habitat for St. Lawrence Beluga (Delphinapterus leucas). DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2009/070, 8 p .
HAMMILL, M., V. LESAGE, J.-F. GOSSELIN, 2009. Stock assessment of northern Quebec (Nunavik) beluga (Delphinapterus leucas). DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2009/016, 13 p .
GOSSELIN, J.-F., V. LESAGE, M. HAMMILL, 2009. Index estimates of abundance for beluga in eastern Hudson Bay, James Bay and Ungava Bay in Summer 2008 ; Indices de l'abondance des bélugas dans l'est de la baie d'Hudson, la baie James et la baie d'Ungava à l'été 2008. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2009/006, 25 p .
The management of beluga whales hunted around Nunavik relies on the estimation of abundance of summering stocks, including the endangered Ungava Bay and eastern Hudson Bay stocks. Systematic aerial line-transect surveys to estimate abundance of beluga whales were conducted in James Bay, eastern Hudson Bay and Ungava Bay from 20 July to 28 August 2008. The flights followed east-west lines with a spacing of 18.5 km in all strata except in the central portion of eastern Hudson Bay, a high coverage area where spacing was reduced by half, i.e. 9.3 km, and the stratum was surveyed twice. A total of 279 beluga clusters was detected between perpendicular distances of 120 m to 2880 m from the track line. The hazard-rate model (AIC = 4145.3) with a lower AIC than the half-normal model (AIC = 4156.9) fitted on the ungrouped perpendicular distance distribution provided an effective strip half width of 839 m (cv = 0.08). Abundance indices were not corrected for availability of diving animals nor for the observer perception. A total of 214 clusters with an average size of 3.99 (cv = 0.31) were detected on 4,279 km of lines in James Bay providing an abundance index of 9,292 (cv = 0.64). A single animal was seen over the 1,246 km surveyed in the low coverage area of eastern Hudson Bay for an abundance index of 13 (cv = 1.02). A group of three animals over 82 km provided an abundance index of 15 (cv =1.03) in the Richmond Gulf (Lac Guillaume-Delisle). There were 2.8 times more beluga whales detected on the first survey of the high coverage area of eastern Hudson Bay than on the second survey of the same area, with 107 clusters of an average size of 2.97 (cv = 0.13) and 45 groups with an average size of 2.49 (cv = 0.30) for the first and second survey, respectively. The abundance indices of 1,797 (cv = 0.27) and 657 (cv = 0.38) for the first and second surveys respectively, provided an average, weighted by effort, of 1,237 (cv = 0.46). No whales were seen in the estuaries of the Nastapoka and Little Whale rivers during coastal surveys. The addition of the low coverage area and Richmond Gulf abundance indices to the weighted average of the two surveys in the high coverage area provided an abundance index for the whole eastern Hudson Bay of 1,265 (cv = 0.45). Beluga whales were not detected in Ungava Bay despite the 4,334 km of offshore survey lines, the coastal surveys done between transect lines and the surveys of the estuaries of the Mucalic, False, George and Koksoak Rivers. Beluga whales were also not detected during the coastal survey of the Hudson Strait from Quaqtaq to Inukjuak conducted on 27 and 28 August. This is the fifth visual systematic survey of James Bay and eastern Hudson Bay. Differences in the surface abundance indices among years and between surveys of the high coverage area of eastern Hudson Bay in 2008, illustrate the challenges to estimate the abundance of small populations with clumped distributions.
LESAGE, V., D. BAILLARGEON, S. TURGEON, D.W. DOIDGE, 2009. Harvest statistics for beluga in Nunavik, 2005-2008 ; Statistiques de chasse au béluga au Nunavik, 2005-2008. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2009/007, 25 p .
The Nunavik communities have traditionally harvested beluga along the eastern Hudson Bay, Hudson Strait and Ungava Bay coasts of northern Quebec. Harvest statistics have been monitored over the last 35 years. Two previous reports summarized the information collected between 1974 and 2004 (Lesage et al. 2001, Lesage & Doidge 2005). The current report provides an update of this information for the period 2005– 2008. Annual harvests declined progressively from an average 450 beluga/yr prior to the introduction of quotas in 1986, to 258 beluga/yr during 1986–2000, 175 beluga/yr during 2001–2004, and 161 beluga/yr during 2005–2008. Compliance with management measures improved after 2002 as indicated by a greater transmission of information through weekly reports, participation in the sampling program, and a general reduction in the total harvest in all regions of the Nunavik. In spite of these improvements, allocations were exceeded almost each year in all regions of Nunavik. Hudson Strait historically supported the largest harvests, and continued to do so during 2005–2008, with 69–92 % of the Nunavik annual harvest. One noticeable change during the period 2001–2008 in comparison with previous years was the large number of communities harvesting in Hudson Strait and the appearance of harvests in non-traditional sites. Although white beluga dominated the harvest during 2005–2008, with 59 % of the total catch, grey beluga, including dark grey animals, represented 41 % of total catches. The sex composition of the harvest indicates that females were killed as often as, or more often than males during this period. This was particularly true for grey beluga, of which females were killed at least twice as often as males. Older beluga were relatively rare in the harvest during 1993 2008 compared with harvests conducted during the 1980s, resulting in a distribution with a median age of 19 to 20 years depending on periods, compared with 26.0 yrs in the 1980s. Beluga killed in Hudson Strait during the 1990s and 2000s were slightly older than those killed in eastern Hudson Bay during the same period.
HAMMILL, M., M.C.S. KINGSLEY, V. LESAGE, J.-F. GOSSELIN, 2009. Abundance of eastern Hudson Bay belugas;Évaluation de labondance des belugas de lest de la Baie dHudson. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2009/009, 22 p .
In previous assessments a population model incorporating density-dependence as well as information on total catches has been fitted to estimates of beluga whale abundance obtained from aerial surveys. In this assessment, a simple exponential model, incorporating information on catches was also fitted to aerial survey estimates of abundance using Bayesian methods. During initial runs, both approaches gave similar results with an estimated 1985 population of 3,900 obtained using the old model, compared to an estimated 4, 100 obtained using the new model. In 2008, the estimated population has declined to 3,200 and 3,000 using the old and new models respectively. It is recommended that the model fitted using Bayesian methods be used in future assessments because the current population is much reduced from pristine levels, such that the effects of density dependent factors are expected to be limited, and the Bayesian approach presents a more rigorous approach to dealing with uncertainty concerning the dynamics of this population and is based on the full multivariate posterior distribution of the parameter estimates. Traditionally, eastern Hudson Bay beluga whales have been made up 12 %, 21 % and 13 % of the harvests from the Belcher Islands, Hudson Strait and Ungava Bay respectively. More recent analyses suggest that the proportion of eastern Hudson Bay animals in the spring Hudson Strait harvest is less than the proportion obtained from the fall harvest. Overall, the sample proportion of eastern Hudson Bay animals has declined to 9 %. No changes were made to model assumptions because the seasonal distribution of samples collected for DNA analyses did not reflect the seasonal distribution of harvesting.
HAMMILL, M., V. LESAGE, 2009. Seasonal movements and abundance of beluga in northern Quebec (Nunavik) based on weekly sightings information ; Renseignements sur les déplacements saisonniers et labondance du béluga dans le nord du Québec (Nunavik) daprès les observations hebdomadaire. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2009/010, 18 p .
The Department of Fisheries and Oceans maintains a harvest reporting system in the 14 villages located in northern Quebec (Nunavik). Data on numbers of animals reported struck, struck and lost and reported observed are recorded on a weekly basis. The reports on numbers of beluga reported observed by hunters were examined to determine if they could be used to examine seasonal movement patterns and to determine if any unusual trends had been observed in recent years. In Ungava Bay, more animals are seen during spring than during other parts of the year, but overall, the number of animals reported are low. Whales are observed throughout the summer, and continue to be seen into the fall. The largest numbers of whales reported were seen in Hudson Strait. Whales were reported from that area in May, with numbers increasing rapidly in June, then declining with few or no whales observed during late July, August and September. Reports indicate an increase in numbers of whales in the Hudson Strait area beginning in October. In Hudson Bay, few animals were observed during the spring, but reports of sighting increasing numbers of whales occurred throughout the early summer, with peaks in sightings from mid-July to early August. An increase in sightings was reported in mid-October, particularly in the northeastern portion of Hudson Bay. Considerable interannual variability in reported numbers of animals sighted were observed, but there was no obvious trend. In Hudson strait there appears to have been a shift in the fall peak of sightings from October to November.
MOSNIER, A., V. LESAGE, J.-F. GOSSELIN, S. LEMIEUX LEFEBVRE, M.O. HAMMILL, T. DONIOL-VALCROZE, 2009. Information relevant to the documentation of habitat use by St. Lawrence Beluga (Delphinapterus leucas), and quantification of habitat quality ; Information pertinente à la documentation de l'utilisation de l'habitat par le béluga du St-Laurent (Delphinapterus leucas) et à la quantification de la qualité de l'habitat. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2009/098, 39 p .
The current population size and distribution range of St. Lawrence beluga are a fraction of those used historically. Their core distribution is centered on the Saguenay River, and is now located between the Battures-aux-Loups-Marins and Rivière-Portneuf / Rimouski in the Estuary, and Baie Ste-Marguerite in the Saguenay River. Concentration areas outside of this sector vary seasonally, as they did in the 1930s, but are now constrained within a zone located between Battures-aux-Loups-Marins and Sept-Îles / Cloridorme (vs west of Quebec City to Natashquan in the 1930s), with only rare observations in the Baie des Chaleurs. St. Lawrence beluga distribution range is small compared to other beluga populations, and even smaller during summer. The timing and extent of seasonal movements of beluga are likely dictated by at least three key drivers: sea ice, predation risks, and food availability. However, little is known about beluga distribution outside of summer. Currently available knowledge indicates that sex- and agesêcific spatial segregation is typical of the species during summer. The Upper Estuary, where females accompanied by calves and juveniles concentrate, is likely an important habitat for calving and juvenile rearing. Reasons for sexual segregation and habitat characteristics that are critical to the survival of females, juveniles and calves in this sector are unclear. The species also consistently aggregates at certain river mouths during summer, which suggest that they are an essential part of beluga habitat. The functions of these areas are unknown. Several smaller areas where beluga occur on a regular basis or where they spend relatively large proportions of their time exist within their seasonal distribution area, some of which have been identified for the summer period. However the current understanding of the functions and key features of these habitats and of habitat use and movements among these areas by beluga does not allow the assessment of their relative importance for the survival of the population. Given that current distribution is small relative to that used historically, a degradation of key habitat features or a reduction in key habitat availability would probably result in negative effects on recovery. In this context, preserving access to and integrity of areas used currently or historically by a large proportion of the population is considered important for the recovery and future range expansion of the population. Species characteristics such as longevity, social organization and learned behaviours may influence seasonal habitat use, and might delay re-colonization of areas used historically.
LESAGE, V., J.-F. GOSSELIN, M. HAMMILL, M.C.S. KINGSLEY, J. LAWSON, 2007. Ecologically and biologically significant areas (EBSAs) in the Estuary and Gulf St. Lawrence : a marine mammal perspective ; Zones d'importance écologique et biologique (ZIEB) pour l'estuaire et le golfe du Saint-Laurent : une perspective des mammifères marins. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2007/046, 92 p .
The importance of some areas of the Estuary and Gulf of St. Lawrence for the aggregation for marine mammals is a long-recognized phenomenon. In this report, results from three aerial surveys and two satellite-telemetry studies are analysed and combined with results from the existing literature to identify known areas of concentration of marine mammals. The quality of areas of marine mammal concentration and associated functions are assessed against criteria developed to identify Ecologically and Biologically Significant Areas (EBSAs). Based on these criteria, there would be eleven areas of ecological and biological significance for marine mammals: 1) Pointe-des-Monts to Sept-Îles, 2) West of Anticosti, 3) Jacques-Cartier Strait, 4) Strait of Belle-Isle/Mecatina Plateau, 5) Western shelf of Newfoundland, 6) Entrance of St Georges Bay, Newfoundland, 7) Cape Breton Trough, 8) Offshore Gaspé, including the channel of Baie des Chaleurs, 9) North margin of the Laurentian Channel to the south of Anticosti, 10) the St. Lawrence Estuary, and finally, 11) the Shelf of southern Gulf, which would find its importance mainly during the ice-covered period.
HAMMILL, M.O., L.N. MEASURES, J.-F. GOSSELIN, V. LESAGE, 2007. Lack of recovery in St. Lawrence Estuary beluga ; Absence de rétablissement du béluga de l'estuaire du Saint-Laurent. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2007/026, 19 p .
Estimates of pristine population size and changes in abundance of St. Lawrence Estuary beluga were examined over the period 1866-2006. Overhunting led to a decline in abundance from pristine estimates of 7,800 (SE=600) in 1866, to approximately 1,000 animals in 1985. In spite of almost 30 years of protection from hunting, the St. Lawrence Estuary beluga shows no signs of recovery with a current population of approximately 1,100 (SE=300, 95 % CI=500-1,800, rounded to the nearest 100) animals. A carcass monitoring and necropsy program detects on average 15 carcasses per year, which likely represents a fraction of the total number of deaths in this population. The age structure of adult animal carcasses suggests that adult mortality rates (6.5 %/yr) are similar to what would be expected in a hunted Arctic beluga population (7.0 %/yr) (Burns and Seaman 1985). Estimates of reproductive rates are uncertain, and juvenile animals are underrepresented in the stranding record. Among all animals regardless of age class where cause of death could be determined, parasitic and bacterial infections accounted for 38 % of mortality, followed by cancer (15 %), problems during birth (7 %), and trauma (5 %), while various other factors accounted for 7 %. A paucity of diet information limits attempts to model trophic interactions and habitat requirements. Emigration does not appear to be an important factor, but the loss of only 1-2 animals per year has longer term cumulative impacts that are not beneficial to a small population
GOSSELIN, J.-F., M.O. HAMMILL, V. LESAGE, 2007. Comparison of photographic and visual abundance indices of belugas in the St. Lawrence Estuary in 2003 and 2005 ; Comparaison des indices d'abondance photographique et visuels des bélugas de l'estuaire du Saint-Laurent en 2003 et 2005. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2007/025, 27 p .
Beluga abundance in the St. Lawrence estuary and Saguenay River was estimated using photographic and visual aerial surveys from the middle of August to early September in 2003 and 2005. Transects covered an area of 5377 km22 in the estuary which corresponds to the main summer concentration of animals. A total of 311 belugas were counted on 1108 photographs taken on 2 September 2003. This count was increased to 312 animals after taking into account that 0.2 % of the area photographed was masked by glare from the sun. This count was also multiplied by an expansion factor of 2.021, to account for the 49.5 % photo coverage of the estuary. Two animals observed in the Saguenay River were added to the final estimate resulting in a surface abundance index of 632 (SE = 116) beluga for the photographic survey in 2003. Systematic visual line transect surveys were completed along every second line of the photographic survey design in order for the whole area to be covered in a single day. Five visual surveys were flown at an altitude of 305 m in 2003, and another 14 surveys completed in 2005, alternated between altitudes of 305 m and 457 m. Distance analyses were done on the truncated distribution of perpendicular distances from the transect line to account for the areas of lower detectability of animals under (re. left truncation) and away (re. right truncation) from the plane. The perpendicular distance distribution was lefttruncated at 99 m and right-truncated at 1569 m in 2003. Left and right truncations were 155 m and 2172 m respectively for the 305 m altitude, and 213 m and 2355 m respectively at the 457 m altitude in 2005. The combined abundance index of 934 (SE = 105) belugas from the visual line transect surveys in 2003 was 48 % higher than the index from the photographic survey. In 2005, the combined abundance index of 675 (SE = 101) for the lower altitude (305 m) was not significantly different (F = 1.79, p = 0.21) than the combined index of 531 (SE = 62) at the higher altitude (457 m). The altitude did not have a significant effect on effective strip half width, estimated cluster size nor encounter rate. Belugas were more frequent and generally more abundant in the Saguenay River in 2005 than in 2003. Animals were detected in the fjord on 13 of the 14 surveys completed with an average of 39 individuals in 2005, compared to 3 out of 6 surveys with an average of 6 individuals in 2003. Although abundance indices from the visual and photographic methods were not significantly different, additional comparisons should be completed to ensure calibration of these two techniques.
LESAGE, V., J. KEAYS, S. TURGEON, S. HURTUBISE, 2006. Bycatch of harbour porpoises (Phocoena phocoena) in the gillnet fishery of the Estuary and Gulf of St. Lawrence, 2000-2002. J. Cetacean Res. Manage., 8(1): 67-78 .
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 sentinel fishery programme in 2001 and 2002. The questionnaire survey had a low response rate (22 %) and provided bycatch estimates of 2,215 (95 % CI 1,151-3,662) and 2,394 (95 % CI 1,440-3,348) porpoises in 2000 and 2001, respectively. The low number of hauls monitored by at-sea observers prevented the estimation of bycatch levels for several zones and the study area as a whole, and provided only imprecise estimates for all other zones. The results from questionnaires indicated a 24-63 % reduction in harbour porpoise bycatches since the late 1980s, whereas the at-sea observer programme provided bycatch levels for 2001 and 2002 that were unreliable and underestimated, approaching one quarter of those documented in the late 1980s. Although both indices indicated a decrease in bycatches since the late 1980s, the magnitude of this change remains uncertain given the weaknesses associated with the two approaches. Considering the maximum population rate of increase (Rmax) for harbour porpoises as 4 % and the lower and upper 95 % confidence limits (1,440-3,348) of our most reliable estimate of bycatches (i.e. the 2001 questionnaire survey results), the harbour porpoise population in the Gulf of St. Lawrence would need to be at least 36,000-83,700 individuals for current incidental catches to be sustainable. If the rate of increase is less than maximal, e.g. 0.5Rmax or 2 %, then 72,000-167,400 harbour porpoises would be needed to attain sustainability. Kingsley and Reeves (1998) estimated that an average 36,000 to 125,000 porpoises occupied the Gulf of St. Lawrence during the summers of 1995 and 1996. Although the trajectory of the population since it was last surveyed in 1996 is uncertain, these findings suggest that bycatch levels might remain a cause for concern for the harbour porpoise population in the Gulf of St. Lawrence. The results from the comparison between the sentinel fishery and the commercial fishery subjected and not subjected to at-sea observations suggest that fine-scale temporal and spatial changes in fishing activities may greatly affect harbour porpoise bycatch levels. ©2006 International Whaling Commission
ROBILLARD, A., V. LESAGE, M. HAMMILL, 2005. Distribution and abundance of harbour seals (Phoca vitulina concolor) and grey seals (Halichoerus grypus) in the Estuary and Gulf of St. Lawrence during 1994-2001. Can. Tech. Rep. Fish. Aquat. Sci., 2613, 152 p .
The abundance and distribution of harbour seals and grey seals in the Estuary and Gulf of St. Lawrence was assessed using seven aerial visual surveys of the Estuary, including three in June (1995, 1996, 2000) and four in August (1994-1997), and two surveys flown in June in different areas of the Gulf (1996 and 2001). Harbour seal counts at haul-out sites ranged from 389 to 659 individuals in the Estuary compared with 890 individuals for the regions surveyed in the Gulf. Assuming that the haul-out behaviour of harbour seals in our study area is similar to harbour seals in the eastern Pacific, where it has been estimated that about 50-75 % of seals are hauled out during surveys, there may be approximately 4000-5000 harbour seals in the Estuary and Gulf of St. Lawrence. Trend analyses of the abundance of harbour seals in the Estuary since1994 were inconclusive, owing to the small number of surveys available for the analyses. A total of 111 to 723 grey seals were counted at haul-out sites in the Estuary, far fewer than the 2474 grey seals that were observed during the two surveys of the Gulf of St. Lawrence. No attempt was made to correct for the animals in the water. Haul-out counts varied widely between years, suggesting between-year changes in the use of this area by grey seals.
HAMMILL, M.O., V. LESAGE, P. CARTER, 2005. What do harp seals eat? Comparing diet composition from different compartments of the digestive tract with diets estimated from stableisotope ratios. Can. J. Zool., 83: 1365-1372 .
This study compared diet reconstructed from different compartments of the digestive tract of harp seals (Pagophilus groenlandicus (Erxleben, 1777) with the diet estimated using stable carbon and stable nitrogen isotope ratios in mixing models. Diet composition in 18 feeding harp seals (mean age = 2.4 years, SD = 1.8 years, range = 0-6 years) was determined using traditional methods of hard-part identification and reconstruction, and stable carbon and stable nitrogen isotope ratios. Diet composition consisted of 68.8 % (SD = 8.7 %) and 69.6 % (SD = 11.6 %) by mass of invertebrates or 65.0 % (SD = 8.8 %) and 66.5 % (SD = 11.8 %) by energy of invertebrates for the stomach and small-intestine compartments, respectively. Reconstructed diets using material recovered from the large-intestine contents suggested a diet of 43.1 % (SD = 12.2 %) and 38.0 % (SD = 11.9 %) invertebrates using mass and energy, respectively. Stable carbon and stable nitrogen isotope ratios determined for the same individual harp seals suggested a diet consisting of approximately 66.1 % (SD = 117.4) invertebrates, indicating that diet reconstructions based on hard parts from stomachs are likely to be more representative than reconstructions from large-intestine contents. In species that feed on a combination of vertebrates and invertebrates, the use of faecal material to reconstruct diet composition will likely underestimate the importance of invertebrates in the diet.©2005 National Research Council Canada
HAMMILL, M., V. LESAGE, 2005. Évaluation du stock de béluga du nord du Québec (Nunavik) (Delphinapterus leucas). MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2005/020, 12 p .
HAMMILL, M.O., V. LESAGE, J.-F. GOSSELIN, 2005. Abundance of Eastern Hudson Bay belugas ; Évaluation de labondance des bélugas de lest de la Baie dHudson. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2005/010, 19 p .
A population model was used to follow changes in the eastern Hudson Bay (EHB) beluga population since 1985. The model incorporating harvest information was fitted to aerial survey data by adjusting initial population size and estimates of the number of animals struck, but not reported. The number of belugas in eastern Hudson Bay has declined from approximately 4,200 (SE=300) animals in 1985 to 3,100 (SE=800) in 2004. In order to achieve this fit, 1.67 animals are estimated to be lost for every animal reported in the harvest. Overall harvest rates have declined under the current management plan. The rate of decline in this population has also likely slowed. To halt the decline, a reported harvest rates must be reduced to 61 animals (replacement yield)
HAMMILL, M., V. LESAGE, 2005. Stock assessment of Northern Quebec (Nunavik) Beluga (Delphinapterus leucas). DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2005/020, 11 p .
LESAGE, V., D.W. DOIDGE, 2005. Harvest statistics for beluga whales in Nunavik, 19742004 ; Statistiques des captures du béluga au Nunavik, 1974-2004. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2005/012, 24 p .
The Nunavik communities have traditionally harvested beluga along the eastern Hudson Bay, Hudson Strait and Ungava Bay coasts of northern Quebec. Harvest statistics have been monitored over the last 30 years. A first report in 2001 summarized and qualified the information collected since 1974 (Lesage et al. 2001). The current report provides an update of this information for the period 2001-2004. A general decline in annual harvests was observed between the periods preceding and following quota introduction in 1986 after which, total harvests were less variable between years. Annual harvests were relatively similar over the last three years (2002-2004) at 168 to 216 belugas per year, but peaked at 395 belugas in 2001, a level last attained in 1980. Compliance with management measures improved during the period 2001-2004, and especially during 2002-2004, as indicated by a greater transmission of information through weekly reports, and participation in the sampling program, and by a general reduction in the total harvest in all regions of the Nunavik. In spite of these improvements, regional allocations were exceeded almost each year and in each region. Hudson Strait historically supported the largest harvests, and continued to do so during 2001-2004, with 60-84 % of the allocations and 58-84 % of the total annual harvest by Nunavik communities. One noticeable change during the period 2001-2004 in comparison with previous years was the increase in the number of communities harvesting in Hudson Strait. Although white beluga dominated the harvest, with 58 % of the total catches, grey beluga, including dark grey animals, represented 42 % of the catches during 2001-2004. The sex composition of the harvest indicates that females were generally killed as often as, or more often than males, both when considering genders independently of their colour, or when considering either white or grey beluga independently. The harvest during 1993-2004 also comprised a larger proportion of younger individuals than the harvest from the mid-1980s, resulting in a distribution with a median age of 9.5 yrs, compared with 13.0 yrs in the 1980s. This tendency to harvest younger individuals was also observed in the harvests of eastern Hudson Bay (median age = 8.5 yrs) and Hudson Strait (median age = 9.5 yrs).
Systematic aerial line-transect surveys of beluga whales, Delphinapterus leucas, were conducted in James Bay, eastern Hudson Bay, and Ungava Bay from 14 August to 3 September 2001. An estimated 7901 (SE = 1744) and 1155 (SE = 507) belugas were present at the surface in the offshore areas of James Bay and Hudson Bay, respectively. An additional 39 animals were observed in estuaries during the coastal survey, resulting in an index estimate of 1194 (SE = 507) in eastern Hudson Bay. No belugas were observed in Ungava Bay. Observations from systematic surveys conducted in 1993 and 2001 were analyzed using both line-transect and strip-transect methods to allow comparisons with the strip-transect survey conducted in 1985. A population model incorporating harvest information and fitted to the aerial survey data indicates that the number of belugas in eastern Hudson Bay has declined by almost half because of high harvest levels. Subsistence harvest levels must be reduced significantly if this population is to recover.©2004 The Arctic Institute of North America
LESAGE, V., J. KEAYS, S. TURGEON, S. HURTUBISE, 2004. Incidental catches of harbour porpoises (Phocoena phocoena) in the gillnet fishery of the Estuary and Gulf of St. Lawrence in 2000-2002. Can. Tech. Rep. Fish. Aquat. Sci., 2552, 37p .
The incidental catch of harbour porpoises as a by-catch of the gillnet fishery of the Estuary and Gulf of St. Lawrence was evaluated using questionnaires to fishermen in 2000 and 2001, and At-sea Observers and Sentinel Fisheries programs in 2001 and 2002. Of the 2277 fishermen receiving the by-catch questionnaire, 215 (9 %) responded, and 165 reported being actively fishing in 2000 or 2001. Of these, 34 (23%nbsp;%) and 45 (27 %) fishermen recorded having taken a total of 181 and 291 harbour porpoises in 2000 and 2001, respectively. The largest takes were in July and August from zones 4R, Miscou and the North Shore. These takes resulted in mean by-catch rates of 1.25 (SD = 5.0) and 1.76 (SD = 4.7) porpoises per reporting fisherman in 2000 and 2001, respectively. Extrapolation of these by-catch rates to the entire gillnet fishing fleet resulted in an estimated total by-catch of 2180 (95 % CI 1012-3802) and 2478 (95 % CI 1591-3464) porpoises for the Estuary and Gulf of St. Lawrence in 2000 and 2001, respectively. For 2001 and 2002, a total of 786 and 882 bottom-set gillnet hauls that were monitored by At-sea observers recorded harbour porpoise by-catches of 4 and 6 individuals, respectively. At-sea observer activities were conducted in close conjunction with the Atlantic cod and Greenland halibut commercial fishery. However, the low number of hauls that were monitored by At-sea observers prevented the calculation of by-catch estimates for several zones and the study area as a whole, and provided only imprecise estimates for all other zones. Sentinel fisheries resulted in 86 and 77 by-catches in 2001 and 2002, respectively. Depending on the year, incidental takes of harbour porpoises by this fishery peaked in late August or early September, even though their activity peaked earlier, in late July to late August in 2001 and 2002, respectively. The number of takes per haul for the Sentinel fishery was higher than that reported through the At-sea Observer program, even though the former was spread over a longer period, when target species of the fishery might have been less abundant. Significant differences in fishing behaviour were observed between commercial fisheries, commercial fisheries with At-sea observers on board, and Sentinel fisheries. Specifically, Sentinel fisheries soaked nets of similar length but of smaller mesh, at deeper depths, for longer periods, and for a lesser quantity of landed fish than was the case for commercial fisheries with an observer on board. In addition, plotting the fishing locations in the Miscou area (NAFO 4Tn) indicated that at least in August and early September 2001, not only was there no overlap in fishing location between Sentinel fisheries and commercial fisheries under the At-Sea Observer program, but there was also no overlap between commercial fisheries with observers on board and commercial fisheries not subject to an at-sea observation. Commercial and Sentinel fisheries generally followed the 60-m isobath, whereas fishing activities with At-sea observers on board occurred in shallower waters, inside Miscou bank. In 2002, periods of activity by At-sea Observer and Sentinel fisheries in Area 4Tn did not overlap in time, but did overlap spatially.
LESAGE, V., M.O. HAMMILL, K.M. KOVACS, 2004. Long-distance movements of harbour seals (Phoca vitulina) from a seasonally ice-covered area, the St. Lawrence River estuary, Canada. Can. J. Zool., 82: 1070-1081 .
Previous studies of harbour seal (Phoca vitulinaL., 1758) movements indicate that this species is relatively sedentary throughout the year. However, few investigations have examined their movements and seasonal distribution patterns in ice-covered areas. This study used spatial analysis of ice data and movement data from harbour seals collected via satellite (n = 7) and VHF radiotelemetry (n = 15) to explore this species spatial use patterns in a seasonally ice-covered region, the St. Lawrence River estuary, Canada. When solid ice formed within the bays of the estuary, four of the seven satellite-tagged animals (all adult males) left their summer haul-out areas, migrating 266 ± 202 km (range 65-520 km) to over-wintering sites. The seals exhibited preference for areas of light to intermediate ice conditions during the winter months; at least six of the seven seals occupied areas with lighter ice conditions than those that prevailed generally in the study area. Evidence of high abundance of potential prey for harbour seals in the estuary during winter suggests that reduced availability of adequate food resources is not the primary factor which influences the movement and distribution patterns of harbour seals. Movement patterns observed during the ice-free period concur with previously reported harbour seal behaviour; the seals remained near the coast (<6.1-11.0 km from shore) in shallow water areas (<50 m deep in 100 % VHF and 90 % SLTDRs (satellite-linked time-depth recorders)) and travelled only short distances (15-45 km) from capture sites. None of the VHF- or satellite-tagged seals crossed the 350 m deep Laurentian channel, which suggests that this deep body of water might represent a physical barrier to this coastal population.©2004 National Research Council Canada
LESAGE, V., J. KEAYS, S. TURGEON, S. HURTUBISE, 2003. Incidental mortality of harbour porpoises in the gillnet fishery of the Estuary and Gulf of St Lawrence in 2000-2002 ; Prises accidentelles de marsouins communs associées aux pêcheries au filet maillant de l'estuaire du golfe et du Saint-Laurent en 2000-2002. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2003/069, 34 p .
The incidental mortality of harbour porpoises as a by-catch of the gillnet fishery of the Estuary and Gulf of St. Lawrence was evaluated using questionnaires to fishermen in 2000 and 2001, and At-sea Observers and Sentinel Fisheries programs in 2001 and 2002. Of the 2277 fishermen receiving the by-catch questionnaire, 215 (9 %) responded, and 165 reported being actively fishing in 2000 or 2001. Of these, 34 (23%) and 45 (27 %) fishermen recorded having taken a total of 181 and 291 harbour porpoises in 2000 and 2001, respectively. The largest takes were in July and August from zones 4R, Miscou and the North Shore. These takes resulted in mean by-catch rates of 1.25 (SD = 5.0) and 1.76 (SD = 4.7) porpoises per reporting fisherman in 2000 and 2001, respectively. Extrapolation of these by-catch rates to the entire gillnet fishing fleet resulted in an estimated total by-catch of 2180 (95 % CI 1012-3802) and 2478 (95 % CI 1591-3464) porpoises for the Estuary and Gulf of St. Lawrence in 2000 and 2001, respectively. For 2001 and 2002, a total of 786 and 882 bottom-set gillnet hauls that were monitored by At-sea observers recorded harbour porpoise by-catches of 4 and 6 individuals, respectively. At-sea observer activities were conducted in close conjunction with the Atlantic cod and Greenland halibut commercial fishery. However, the low number of hauls that were monitored by At-sea observers prevented the calculation of by-catch estimates for several zones and the study area as a whole, and provided only imprecise estimates for all other zones. Sentinel fisheries resulted in 86 and 77 by-catches in 2001 and 2002, respectively. Depending on the year, incidental takes of harbour porpoises by this fishery peaked in late August or early September, even though their activity peaked earlier, in late July to late August in 2001 and 2002, respectively. The number of takes per haul for the Sentinel fishery was higher than that reported through the At-sea Observer program, even though the former was spread over a longer period, when target species of the fishery might have been less abundant. Significant differences in fishing behaviour were observed between commercial fisheries, commercial fisheries with At-sea observers on board, and Sentinel fisheries. Specifically, Sentinel fisheries soaked nets of similar length but of smaller mesh, at deeper depths, for longer periods, and for a lesser quantity of landed fish than was the case for commercial fisheries with an observer on board. In addition, plotting the fishing locations in the Miscou area (NAFO 4Tn) indicated that at least in August and early September 2001, not only was there no overlap in fishing location between Sentinel fisheries and commercial fisheries under the At-Sea Observer program, but there was also no overlap between commercial fisheries with observers on board and commercial fisheries not subject to an at-sea observation. Commercial and Sentinel fisheries generally followed the 60-m isobath, whereas fishing activities with At-sea observers on board occurred in shallower waters, inside Miscou bank. In 2002, periods of activity by At-sea Observer and Sentinel fisheries in Area 4Tn did not overlap in time, but did overlap spatially.
LESAGE, V., M.O. HAMMILL, 2003. Proceedings of the workshop on the development of research priorities for the northwest Atlantic blue whale population. DFO, Canadian Science Advisory Secretariat, Proceedings Series ; MPO, Secrétariat canadien de consultation scientifique, Série des comptes rendus, 2003/031, 35 p .
A workshop to identify research priorities for the Northwest Atlantic blue whale population was held in Quebec City on November 20-21st, 2002. Filling in knowledge gaps regarding this endangered species is a key element in the development and implementation of a recovery strategy, planned for 2003-2004. Presentations summarized existing research programs in Canada, the U.S. and Iceland. Participants reviewed the knowledge gaps and threats to the blue whale as identified in the COSEWIC report. Important knowledge gaps that were identified included a lack of knowledge on seasonal distribution, abondance, stock structure and seasonal movements. Research priorities also identified a need to determine and define breeding and feeding areas, and the extend to which physical and biological processes determine distribution, behavior, and movements. This information will help define critical habitat as requested by the Species at Risk Act. Participants also identified the most effective approaches for addressing particular knowledge gaps, and evaluated the pros and cons of each approach such as photo-identification, passive acoustics, visual surveys, genetics, telemetry etc. Actions to be undertaken were listed according to priorities. These recommandations will aid DFO managers in evaluationg future research needs in light of the blue whale recovery strategy.
HAMMILL, M.O., V. LESAGE, 2002. Le béluga (Delphinapterus leucas) du Nord du Québec (Nunavik). Rapport sur l'état des stocks, E4-01, 10 p .
HAMMILL, M., V. LESAGE, 2002. Northern Quebec (Nunavik) beluga (Delphinapterus leucas). Science, Stock Status Report, E4-01, 8 p .
BOURDAGES, H., V. LESAGE, M.O. HAMMILL, B. DE MARCH, 2002. Impact of harvesting on population trends of beluga in eastern Hudson Bay ; Impact de la chasse sur la tendance de la population de bélugas de l'est de la Baie d'Hudson. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2002/036, 46 p .
Inuit people from the Nunavik have traditionally harvested beluga along the eastern Hudson Bay (EHB), Hudson Strait and Ungava coasts of northern Quebec. Quotas and other management measures exist since 1986, and are revised periodically. The current management plan and recommendations for harvest levels in the Nunavik region were established in April 2001 based on the best available data, i.e. population size in 1985 and 1993, and harvest statistics from 1974-2000. This study presents different scenarios of past and future harvests, while incorporating new information on beluga abundance in James Bay, EHB, Hudson Strait, and Ungava Bay, genetic composition of the harvests, and harvest statistics from 2001. Harvest statistics indicate that the communities of Nunavik exceed quotas each year. Both a relatively simple model using population estimates, removals and rate of increase, and a more complex model introducing additional variables on stage-specific biological parameters were used to examine the impact of harvesting on the growth of the eastern Hudson Bay beluga population. The two models yielded very similar results. They both indicated a decline in EHB beluga population since 1985, a population size in 2001 of approximately 2045 individuals (2090 vs 2001), and an underreporting of harvests prior to 1995 by a factor of 2.23-2.22. The short- and longer-term impacts of future harvesting on the EHB beluga population were examined under different scenarios. However, the probability of decline on the short-term changed little between a harvest of 0 (48 %) or 150 (56 %) beluga from the EHB stock owing to the uncertainty surrounding the current estimates of population size. However, more certainty of a decline is acquired over time, and the influence of the number of removals per year is revealed more clearly over a longer time period. There is a 70-80 % certainty of a decline in five or 10 years if over-harvesting practices similar to what was observed in 2001 (i.e. 125-150 EHB beluga) continue in the future. Reducing the quota to 25 beluga results in a 45 % probability of a smaller stock in five years, whereas a complete cessation of EHB beluga harvesting results in a 35-40 % probability that the stock will show now further decline in 5 years. Using minimum population estimates of 1657 and 1423 individuals for EHB beluga for Model 1 and 2, respectively, and a maximum annual rate of increase of 4 %, the potential biological removal (PBR) is 15 individuals, assuming a recovery factor of 0.5 (for a threatened population which is not in decline). The PBR decreases to 9 beluga if this threatened population is assumed to be declining (recovery factor of 0.3), and to 3 beluga if it is considered endangered (recovery factor of 0.1). In contrast with the EHB population, numbers of beluga in James Bay appear to have increased since 1985 to an estimated 10,504 beluga in 2001 (assuming an annual rate of increase of 0.03 to 0.04). The model fitted best the data when it was allowed to optimise the rate of increase. In this scenario, this population grew at a rate of 0.087 and was estimated to number 15,954 beluga in 2001.
LESAGE, V., M.O. HAMMILL, K.M. KOVACS, 2002. Diet-tissue fractionation of stable carbon and nitrogen isotopes in phocid seals. Mar. Mamm. Sci., 18: 182-193 .
GOSSELIN, J.-F., V. LESAGE, M.O. HAMMILL, H. BOURDAGES, 2002. Abundance indices of beluga in James Bay, eastern Hudson Bay and Ungava Bay in summer 2001 ; Indices d'abondance de bélugas dans la baie James, l'est de la baie d'Hudson et la baie d'Ungava durant l'été 2001. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2002/042, 28 p .
Aerial systematic line transect surveys of beluga whales, Delphinapterus leucas, were conducted in James Bay, eastern Hudson Bay and Ungava Bay from 14 August to 3 September 2001. Coastal surveys were conducted on 28 August in Eastern Hudson Bay, on 4 September in Ungava Bay and on 5 September in Hudson Strait and along the northeastern Hudson Bay coast. An effective strip width of 638 m was estimated from the 717 beluga observed on east-west lines in James Bay (557 beluga) and eastern Hudson Bay(160 beluga). An estimated 7,901 (SE = 1,744) and 1,155 (SE = 507) beluga were present at the surface in the offshore areas of James Bay and Hudson Bay respectively. An additional 39 animals were observed in estuaries during the coastal survey resulting in an index estimate of 1,194 (SE = 507) in eastern Hudson Bay. No beluga were observed in Ungava Bay. Three beluga were observed along the coast near Salluit. Observations from the 1993 and 2001 systematic surveys were analysed using both line transect and strip transect methods to allow comparisons with the strip transect survey conducted in 1985. From 1985 to 2001, the number of beluga summering in James Bay increased fourfold, while numbers in eastern Hudson Bay have declined by almost half.
LESAGE, V., M.O. HAMMILL, K.M. KOVACS, 2001. Marine mammals and the community structure of the Estuary and Gulf of St. Lawrence, Canada: evidence from stable isotope analysis. Mar. Ecol. Prog. Ser., 210: 203-221 .
The trophic relationships of both the benthic and pelagic communities in the Estuary and Gulf of St. Lawrence regions were examined, with a special focus on the trophic position (TP) and relationship(s) among harbour, grey, hooded seals and beluga whales. A multiple stable isotope and multiple tissue approach, used in conjuction with conventional dietary information, suggested that marine mammals occupied the highest trophic positions in the food webs on both communities and that they overlapped with one another to some extent tropically. Harbour seals Phoca vitulina and hooded seals Cystophora cristata occupied the highest TP, grey seals Halichoerus grypus, Gulf harp seals Phoca groenlandica, and male beluga whales Delphinapterus leucas were intermediate, and Estuary harp seals and female beluga whales were at the lowest TP. A general pattern of increasing enrichment of 13C or 15N with age was observed in marine mammals (as well as fishes), although yearlings showed a decreased enrichment compared to both younger and older age classes. Sex also influenced 15N values. Males were more 15N-enriched than females, with the difference between the sexes increasing with age, and being most pronounced in species that are sexually dimorphic with respect to body size. Geographical location also influenced isotope abundance. Estuary organisms were generally 13C-enriched relative to Gulf animals. 13C values were on average lower in short-term diet integrators (blood serum) than in longer-term diet integrators (red blood cells) of harbours seals captured in April to June in the Estuary, which suggests that they probably did not move outside the Lower Estuary during the winter. Grey seals captured in the Lower Estuary did, however, show evidence of having been in the Gulf region some weeks or months before capture.
LESAGE, V., M.O. HAMMILL, 2001. The status of the Grey seal (Halichoerus grypus) in the Northwest Atlantic. Can. Field-Nat., 115: 653-662 .
HAMMILL, M.O., V. LESAGE, 2001. Le béluga (Delphinapterus leucas) du Nord du Québec (Nunavik). Rapport sur l'état des stocks, E4-01, 8 p .
GOSSELIN, J.-F., V. LESAGE, A. ROBILLARD, 2001. Population index estimate for the beluga of the St. Lawrence River Estuary in 2000. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2001/049, 21 p .
Abundance of beluga in the St. Lawrence estuary was estimated from an aerial survey flown on 28 August 2000. Two fixed-wing aircrafts equipped with 9"x9" format mapping cameras flew 52 strip transects across the Estuary between Baie St-Paul and Rimouski for a total survey coverage of 49.3%. A visual survey to count beluga in the Saguenay River was flown at the same time. In the estuary, 453 (SE = 54) beluga were estimated to be at the surface between Kamouraska and Les Escoumins after correction for sun glare, and 6 beluga were counted downstream of Baie Ste-Marguerite in the Saguenay River. A 15 % correction factor was applied to the estimated number of beluga at the surface in the estuary to account for beluga missed because they were underwater. Adding the Saguenay River count to the corrected estimate resulted in an index count of 527 (SE = 62). This corrected index used in trend analysis along with 5 equivalent survey indices obtained between 1988 and 1997, revealed no significant changes in abundance of beluga in the St. Lawrence estuary since 1988.
HAMMILL, M.O., V. LESAGE, Y. DUBÉ, L.N. MEASURES, 2001. Oil and gas exploration in the Southeastern Gulf of St. Lawrence : a review of information on Pinnipeds and Cetaceans in the area. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2001/115, 40 p .
Information on pinnipeds (seals) and cetaceans (whales) in the proposed region of oil and gas exploration in the southeastern Gulf of St. Lawrence were summarized. Cabot Strait is an important migratory corridor for marine mammals moving in and out of the Gulf of St. Lawrence. Other major features of the area include seasonal ice cover which provides a platform for pinniped reproduction and limits access of marine mammals (primarily cetaceans) to the Gulf of St. Lawrence during winter months. The presence of large canyons in the Gulf, and particularly the Cape Breton Trough near Cheticamp are important foraging areas for cetaceans. Four pinniped species are common to the area: harp, hooded, grey and harbour seals. General knowledge on population abundance, whelping areas, distribution, and diet are available for these animals, but specific (local) at sea distribution, relative abundance and local diet information in the area are needed. Harbour seals form the basis of a seal-watching industry on the east coast of Prince Edward Island. At least 15 whale species may occur or pass through Cabot Strait. Six are abundant regular visitors. Fin, Minke, Humpback, and Pilot whales, White-sided dolphins, and Harbour porpoise are seen regularly, while low numbers of Right whales regularly transit the area. The area appears to be particularly important for Pilot Whales and this species forms the basis of whale-watching activities on western Cape Breton Island. Overall, a major knowledge gap is a lack of information on species present, abundance, seasonal occupation, seasonal movements and diet of whales in the southeastern Gulf of St. Lawrence. Seismic activity could cause physical damage to hearing, result in distribution changes due to noise or changes in food distribution. Increases in strandings have been linked to increases in man-made noise production. Pilot whales, a species that often strands in the area, would appear to be particularly vulnerable.
LESAGE, V., D. W. DOIDGE, R. FIBICH, 2001. Harvest statistics for beluga whales in Nunavik, 1974-2000 ; Statistiques de chasse du béluga du Nunavik, 1974-2000. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2001/022, 35 p .
The Nunavik communities have traditionally hunted beluga along the eastern Hudson Bay, Hudson Strait and Ungava Bay coasts of northern Quebec. Catch levels by these communities have been monitored over the last twenty-six years, and this report summarises available information on these statistics from 1974 to 2000. Between 1974 and 1986, an average of 243 beluga were harvested annually by the four Hudson Strait communities, whereas 124 and 83 animals were harvested by three communities in eastern Hudson Bay, and five communities in Ungava Bay, respectively. During that period, a decline in beluga harvests was observed in each region, and in several communities, although it occurred later (post 1981) in eastern Hudson Bay than in Hudson Strait and Ungava Bay (post 1978). The location of harvest, some biological samples, and the age, sex and colour composition of catches were provided by hunters for beluga harvested during 1993-2000. Beluga are harvested during summer by the communities of Kuujjuaraapik, Umiujaq, and Inujjuaq in the south-eastern Hudson Bay, and during October by Akulivik and Puvirnituq in the north-eastern Hudson Bay. Hudson Strait communities harvest beluga in the fall and spring when animals move in and out of the Strait. Ungava Bay communities tend to follow the same pattern since the imposition, in 1986, of restrictions on beluga harvests in Ungava Bay. In recent years, Akulivik and Puvirnituq tend to harvest part, or most, of their quota from the Ivujivik area in south-western Hudson Strait, while Ungava Bay communities harvested beluga both from the Ungava Bay and the Quartaq area, in south-eastern Hudson Strait. Depending on region, grey beluga represented 46 to 51 % of harvests, and females, 47 to 60 % of catches during 1993-2000. The proportion of white males (23-30 %) in harvests was near the percentage expected if animals were taken at random (i.e. 25 %) during 1995-2000, even though management plans recommended that harvesting be directed towards white males. A comparison of the age frequency distributions of beluga harvested during the mid 1980s and the 1990s, indicates a recent, statistically significant change in the age composition of the harvest. During 1980-1987, the median age of beluga taken by the Nunavik communities was 14 yrs, whereas this value decreased to 9 yrs during 1993-1999. This tendency was even more pronounced for the three southernmost communities of eastern Hudson Bay and the communities from Ungava Bay, with median ages of 8.0 yrs and 8.5 yrs, respectively. The number of beluga sampled from Puvirnituqs harvest during October in south-western Hudson Strait is small (n = 13) but indicates 50 % of the harvest is young, aged lower than 7.5 yrs.
PILLET, S., V. LESAGE, M. HAMMILL, D.G. CYR, J.M. BOUQUEGNEAU, M. FOURNIER, 2000. In vitro exposure of seal peripheral blood leukocytes to different metals reveal a sex-dependent effect of zinc on phagocytic activity. Mar. Pollut. Bull., 40: 921-927 .
HAMMILL, M.O., V. LESAGE, 2000. La recherche sur le phoque commun (Phoca vitulina) dans le cadre de Saint-Laurent - Vision 2000 : sommaire des activités. Naturaliste can., 124(1): 61-63 .
LESAGE, V., C. BARRETTE, M.C.S. KINGSLEY, B. SJARE, 1999. The effect of vessel noise on the vocal behavior of belugas in the St. Lawrence River Estuary, Canada. Mar. Mamm. Sci., 15; 65-84 .
LESAGE, V., M.O. HAMMILL, K.M. KOVACS, 1999. Functional classification of harbor seal (Phoca vitulina) dives using depth profiles, swimming velocity, and an index of foraging success. Can. J. Zool., 77: 74-87 .
Time-depth-speed recorders and stomach-temperature sensors were deployed on 11 harbor seals (Phoca vitulina) in the St. Lawrence estuary to examine their diving and foraging behavior. Fifty-four percent of dives were to depths of <4 m. Dives that were ≥4 m deep were classified into five distinct types, using a combination of principal components analysis and hierarchical and nonhierarchical clustering analyses. Feeding, indicated by a sharp decline in stomach temperature, occurred during dives of all five types, four of which were U-shaped, while one was V-shaped. Seals swam at speeds near the minimum cost of transport (MCT) during descents and ascents. V-shaped dives had mean depths of 5.8 m, lasted an average of 40 s, and often preceded or followed periods of shallow-water (<4 m) activity. Seals invariably dove to the bottom when performing U-shaped dives. These dives were to an average depth of 20 m during daylight and occurred in shallower waters (~8 m) at twilight and during the night. Once on the bottom, seals (i) swam at MCT speeds with occasional bursts of speed, (ii) swam at speeds near MCT but not exceeding it, or (iii) remained stationary or swam slowly at about 0.15 m/s, occasionally swimming faster. It is unlikely that all dives to depths ≥4 m are dedicated to foraging. However, the temporal segregation of dive types suggests that all types are used during foraging, although they may represent different strategies© National Research Council Canada
LESAGE, V., M.C.S. KINGSLEY, 1998. Updated status of the St. Lawrence River population of the beluga, Delphinapterus leucas. Can. Field-Nat., 112: 98-114 .
LESAGE, V., M.O. HAMMILL, K.M. KOVACS, 1995. Harbour seal (Phoca vitulina) and grey seal (Halichoerus grypus) abundance in the St. Lawrence Estuary. Can. Manuscr. Rep. Fish. Aquat. Sci., 2307, 22 p .
An aerial survey and several boat surveys were conducted during April-September 1994 to obtain information on harbour and grey seal abundance and distribution in the Saint-Lawrence Estuary. A total of 389 harbour seals and 111 grey seals were counted on or near haul-out sites during the aerial survey flown in August.
LESAGE, V., M.C.S. KINGSLEY, 1995. Bilan des connaissances de la population de bélugas (Delphinapterus leucas) du Saint-Laurent. Rapp. tech. can. sci. halieut. aquat., 2041, 51 p .
The St. Lawrence population of belugas (Delphinapterus leucas) is much reduced, numbering now about 500-600 individuals. Although the population is not exploited, its growth rate is apparently small. Reduced genetic variability within the population, and the rarity of beluga sightings outside the limit of distribution in the Gulf suggest that it forms a geographically and genetically isolated population. In the St. Lawrence, the belugas show reproductive rates, survival rates at age and population age structure similar to those of other populations. It has been suggested that the high levels of some organochlorines recorded in the St. Lawrence belugas may induce immunitary and reproductive deficiencies. Although the ovarian activity of St. Lawrence beluga appear similar to that observed for other beluga populations, further work is needed to verify this hypothesis.
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