scholarly journals Assessing spatial segregation of beluga whales (Delphinapterus leucas) in Western Hudson Bay estuaries

2021 ◽  
Author(s):  
Kristin H Westdal ◽  
Jeremy Davies ◽  
Steve Ferguson
Keyword(s):  
Environmental Data ◽  
Beluga Whale ◽  
Habitat Characteristics ◽  
Delphinapterus Leucas ◽  
Hudson Bay ◽  
Adult Males ◽  
Coastal Habitat ◽  
Age Classes ◽  
Age Class ◽  
Western Hudson Bay

Segregation of older adult males from females and immature males is known to occur in some beluga whale populations, but it is unclear if adults accompanied by calves segregate in Hudson Bay, where the largest summering population is found. Using imagery from a photographic aerial survey conducted in August 2015, we considered a number of environmental variables that might explain distribution by age class of beluga near two of three main estuaries (Churchill and Seal River) used by Western Hudson Bay belugas in the summer season. Belugas were identified and classified by age manually using an identification decision tree and GPS coordinates were plotted in ArcGIS.  Distribution by age class was examined in relation to distance to coastal habitat and bathymetry to test the predation risk hypothesis, sea surface temperature (thermal advantage hypothesis), and extent of river plume (forge-selection hypothesis). Habitat characteristics and the proportion of age classes in both estuaries were similar between age class groups (with and without calves) indicating no segregation and suggesting the environmental data assessed were not driving patterns of distribution and density of age classes at the spatial and temporal scale being investigated. Results provide a greaterunderstanding of spatial patterns of beluga whale habitat use in western Hudson Bay and information useful in conservation and management advice.

scholarly journals Beluga whale summer habitat associations in the Nelson River estuary, western Hudson Bay, Canada

PLoS ONE ◽  
2017 ◽  
Vol 12 (8) ◽  
pp. e0181045 ◽  
Author(s):  
Alexander J. Smith ◽  
Jeff W. Higdon ◽  
Pierre Richard ◽  
Jack Orr ◽  
Warren Bernhardt ◽  
...  
Keyword(s):  
River Estuary ◽  
Habitat Associations ◽  
Beluga Whale ◽  
Hudson Bay ◽  
Western Hudson Bay

Polar bear (Ursus maritimus) maternity denning habitat in western Hudson Bay: a bottom-up approach to resource selection functions

2005 ◽  
Vol 83 (6) ◽  
pp. 860-870 ◽  
Author(s):  
Evan Richardson ◽  
Ian Stirling ◽  
David S Hik
Keyword(s):  
Resource Selection ◽  
Polar Bear ◽  
Vegetation Index ◽  
Landsat Imagery ◽  
Ursus Maritimus ◽  
Habitat Characteristics ◽  
Tree Cover ◽  
Selection Function ◽  
Hudson Bay ◽  
Western Hudson Bay

We examined habitat characteristics of 101 polar bear (Ursus maritimus Phipps, 1774) den sites and 83 adjacent unoccupied sites in western Hudson Bay, Canada, between mid-August and early October 2001 and 2002. Bears denned almost exclusively in peat banks (n = 100) along the edges of creeks, rivers, and lakes adjacent to open lichen tundra sites. Den sites differed from unoccupied sites by having greater tree cover (P = 0.002), less moss cover (P < 0.001), and less herbaceous cover (P = 0.005). The presence of tree roots improved substrate stability, providing support to den structures. Den entrance azimuths were weighted toward a southeasterly aspect (P < 0.005), away from the prevailing northwest winds. To identify habitats with the greatest relative probability of having a den, a resource selection function (RSF) model was developed using remote sensing imagery and 1245 known den locations. High normalized difference vegetation index and brightness values derived from Landsat imagery, which were in close proximity to water, corresponded well with polar bear den sites. Identification of critical denning areas through the use of RSF will provide resource managers with a valuable tool for ensuring the protection of denning habitat, and consequently female bears and their young.

Biology of White Whales (Delphinapterus leucas) in Western Hudson Bay

1973 ◽  
Vol 30 (8) ◽  
pp. 1065-1090 ◽  
Author(s):  
D. E. Sergeant
Keyword(s):  
Crude Birth Rate ◽  
Late Summer ◽  
Reproductive Rate ◽  
Delphinapterus Leucas ◽  
Corpora Lutea ◽  
Hudson Bay ◽  
Decapod Crustacea ◽  
The Mean ◽  
Western Hudson Bay ◽  
Frequent Presence

The number of white whales inhabiting western Hudson Bay is about 10,000. In July and early August the herds are concentrated in river estuaries at 57° to 60° N, but a migration in mid-August through September takes them to between 62° and 66°N. Wintering occurs in the western part of the Bay. In the estuary of the Churchill River feeding, mainly on fish, is not heavy and the herds are believed to enter the river estuaries in this region for reproduction as much as feeding. Further north in late summer feeding is heavier and changes towards a diet of decapod Crustacea. It is believed that two dentinal layers are laid down in the teeth each year, each layer consisting of one opaque and one translucent zone of dentine, with the translucent material laid down during periods of reduced feeding. These may occur either at an autumn and a spring migration or during a summer fast at calving time and during winter deprivation. Females attain sexual maturity at 8–13 (mean 10) growth layers and males at 16–18 layers, i.e. at supposed mean ages of 4–7 (5) and 8–9 years. The skin loses all trace of grey color at 18–22 layers. Maximal duration of life is about 50 layers or a supposed age of 25 years in both sexes. The sexes are probably about equal in numbers. Gestation lasts 14 months and lactation about 20 months. Overlap of pregnancy and the previous lactation is infrequent so that calving occurs about once in 3 years. The annual crude birth rate is estimated at 0.12. Estimation of the maximal number of births from counts of corpora luteal scars is complicated by the frequent presence of accessory corpora lutea and luteinized follicles, estimated at about 32% of the total. The mean maximal number of scars retained in the ovaries during a female’s reproductive lifetime is 14.5. The full reproductive lifetime, on the basis of two growth layers per annum, is 20 years. Thus the mean ovulation rate is about 0.7 per annum. Reducing the number of scars by 32% gives 0.5 true (fertile) ovulations per annum, which would indicate a reproductive rate of one pregnancy in 2 years, and a maximal number of 10 pregnancies in a full reproductive lifetime

Comparative hunting abilities of polar bear cubs of different ages

1978 ◽  
Vol 56 (8) ◽  
pp. 1768-1772 ◽  
Author(s):  
Ian Stirling ◽  
Paul B. Latour
Keyword(s):  
Polar Bear ◽  
Canadian Arctic ◽  
Ursus Maritimus ◽  
Adult Males ◽  
Age Classes ◽  
Adult Age ◽  
Probability Of Survival ◽  
Age Class ◽  
Management Concept ◽  
Kill Rate

In most areas of the Canadian Arctic polar bear (Ursus maritimus) cubs apparently remain with their mothers until they are 2.5 years of age. The degree to which cubs of each age-class participate in the hunting of seals while with their mothers is examined in this paper in order to evaluate the degree to which they might be capable of independent hunting, should they be orphaned prior to the completion of the normal weaning period. Cubs of all age-classes did almost no hunting during the spring. The proportions of time spent hunting by yearling and 2-year-old cubs, and the durations of their lying 'still hunts' were not significantly different from each other but they were significantly shorter than their mothers' and than adult males' during the summer. However, the frequency of the lying 'still hunts' of 2-year-old cubs was double that of yearling cubs and the kill rate of 2-year-old cubs was comparable with that of adult age-classes, despite the fact they hunted for a significantly lesser proportion of their time. These results suggest that cubs which remain with their mothers until they are weaned have a higher probability of survival than those that do not and this interpretation lends support lo the management concept of total protection of family groups and the harvesting of independent bears only.

Whale milk. I. Fin whale (Balaenoptera physalus) and beluga whale (Delphinapterus leucas) milk: gross composition and fatty acid constitution

1969 ◽  
Vol 47 (1) ◽  
pp. 95-97 ◽  
Author(s):  
B. H. Lauer ◽  
B. E. Baker
Keyword(s):  
Fatty Acid ◽  
North Atlantic ◽  
Beluga Whale ◽  
Delphinapterus Leucas ◽  
Hudson Bay ◽  
Balaenoptera Physalus ◽  
Fin Whale ◽  
The North ◽  
The North Atlantic ◽  
Beluga Whale Delphinapterus Leucas

Milk was obtained from a fin whale which was killed in the North Atlantic and from a beluga whale which was killed in Hudson Bay. The gross composition and fatty acid constitution of the milks were determined.

Temporal variation in reproduction and body mass of polar bears in western Hudson Bay

1995 ◽  
Vol 73 (9) ◽  
pp. 1657-1665 ◽  
Author(s):  
Andrew E. Derocher ◽  
Ian Stirling
Keyword(s):  
Body Mass ◽  
Litter Production ◽  
Hudson Bay ◽  
Polar Bears ◽  
Age Classes ◽  
Study Recruitment ◽  
Term Variation ◽  
Long Term Trends ◽  
Western Hudson Bay

We studied annual and long-term variation in rates of reproduction in female polar bears (Ursus maritimus) in western Hudson Bay from 1966 to 1992. In addition, long-term trends in body mass were examined from 3146 captured polar bears. Reproduction rates declined in the late 1980s from higher levels in 1966–1984. Litter production decreased from 0.48 to 0.34 litters per female each year over the study. Recruitment to autumn declined from 0.75 to 0.52 cubs per female each year, in part because of cub mortality between spring and autumn, which increased from 25.0% in 1980–1984 to 50.9% in 1987–1992. Spring and autumn litter sizes of females with cubs did not vary annually, but litter sizes of females with yearlings varied between years. The proportion of yearlings independent of their mother in autumn dropped from 81% prior to 1980 to 34% in 1980–1992. After 1986, offspring remained with their mothers longer, resulting in the birth interval increasing from 2.1 to 2.9 years. Body mass of most age-classes of females and males declined in the 1980s. Unlike earlier studies that found reproduction rates to be higher in western Hudson Bay than in higher latitude populations, reproduction rates in 1986–1992 in western Hudson Bay were similar to those of other populations. Insufficient information was available to determine the cause of declines in reproduction and body mass.

scholarly journals Inuit Knowledge of beluga whale (Delphinapterus leucas) foraging ecology in Nunavik (Arctic Quebec), Canada

2016 ◽  
Vol 94 (10) ◽  
pp. 713-726 ◽  
Author(s):  
K. Breton-Honeyman ◽  
M.O. Hammill ◽  
C.M. Furgal ◽  
B. Hickie
Keyword(s):  
Diet Composition ◽  
Foraging Ecology ◽  
Arctic Region ◽  
Beluga Whale ◽  
The Arctic ◽  
Delphinapterus Leucas ◽  
Hudson Bay ◽  
Productive Area ◽  
Inuit Knowledge ◽  
Beluga Whale Delphinapterus Leucas

The beluga whale (Delphinapterus leucas (Pallas, 1776)) is expected to be influenced by changes in the environment. In Nunavik, the Arctic region of Quebec, Nunavimmiut (Inuit of Nunavik) have depended on beluga for centuries, developing an extensive understanding of the species and its ecology. Forty semidirective interviews were conducted with Inuit hunters and Elders from four Nunavik communities, who had a range of 28–47 years of beluga hunting experience. Interviews followed an ethnocartographic format and were analyzed using a mixed methods approach. Hunters most commonly reported prey species from the sculpin (Cottidae), cod (Gadidae), salmon (Salmonidae), and crustacean families; regional variations in prey and in foraging habitat were found. Hunters identified significant changes in body condition (i.e., blubber thickness), which were associated with observations about the seasonality of feeding. The timing of fat accumulation in the late fall and winter coupled with the understanding that Hudson Bay is not known as a productive area suggest alternate hypotheses to feeding for the seasonal movements exhibited by these whales. Inuit Knowledge of beluga foraging ecology presented here provides information on diet composition and seasonality of energy intake of the beluga and can be an important component of monitoring diet composition for this species into the future. An Inuttitut version of the abstract is available ( Appendix A ).

Tagging White Whales in the Canadian Arctic

1969 ◽  
Vol 26 (8) ◽  
pp. 2201-2205 ◽  
Author(s):  
D. E. Sergeant ◽  
P. F. Brodie
Keyword(s):  
Shallow Water ◽  
Canadian Arctic ◽  
The Body ◽  
Delphinapterus Leucas ◽  
Hudson Bay ◽  
Western Coast ◽  
Dorsal Part ◽  
Dorsal Ridge ◽  
Western Hudson Bay

White whales, Delphinapterus leucas Pallas, were tagged in the estuary of Seal River, Man., in western Hudson Bay in the summers of 1967 and 1968. Seven hundred harpoon tags were applied to the dorsal part of the body while chasing the animals, and 118 Petersen disc tags through the dorsal ridge after stranding the animals in shallow water on a falling tide. Three recovered harpoon tags include one observed on a living whale at the same site after a year, and two taken from netted whales at fisheries northward along the western coast of Hudson Bay, 300–800 km from the site of tagging and 5–7 weeks after tagging.

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