Body Size in White Whales, <i>Delphinapterus leucas</i>

Sergeant, David; Brodie, Paul F.

doi:10.1139/f69-251

Cited by 80 publications

(89 citation statements)

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“…neonates (Sergeant and Brodie 1969), and the presence of freshwater and coarse substrates facilitating skin shedding during molt (St. Aubin et al 1990, Frost et al 1993. The relative importance of each of those factors likely varies based on the environmental conditions (e.g., water temperatures and prey availability) specific to each of the summering areas (Frost and Lowry 1990a).…”

Section: Cetaceansmentioning

confidence: 99%

Quantifying the Sensitivity of Arctic Marine Mammals to Climate-Induced Habitat Change

Laidre

Stirling²,

Lowry

et al. 2008

Ecological Applications

626

547

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Abstract. We review seven Arctic and four subarctic marine mammal species, their habitat requirements, and evidence for biological and demographic responses to climate change. We then describe a pan-Arctic quantitative index of species sensitivity to climate change based on population size, geographic range, habitat specificity, diet diversity, migration, site fidelity, sensitivity to changes in sea ice, sensitivity to changes in the trophic web, and maximum population growth potential (R max ). The index suggests three types of sensitivity based on: (1) narrowness of distribution and specialization in feeding, (2) seasonal dependence on ice, and (3) reliance on sea ice as a structure for access to prey and predator avoidance. Based on the index, the hooded seal, the polar bear, and the narwhal appear to be the three most sensitive Arctic marine mammal species, primarily due to reliance on sea ice and specialized feeding. The least sensitive species were the ringed seal and bearded seal, primarily due to large circumpolar distributions, large population sizes, and flexible habitat requirements. The index provides an objective framework for ranking species and focusing future research on the effects of climate change on Arctic marine mammals. Finally, we distinguish between highly sensitive species and good indicator species and discuss regional variation and species-specific ecology that confounds Arctic-wide generalization regarding the effects of climate change.

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Section: Cetaceansmentioning

confidence: 99%

Quantifying the Sensitivity of Arctic Marine Mammals to Climate-Induced Habitat Change

Laidre

Stirling²,

Lowry

et al. 2008

Ecological Applications

626

547

View full text Add to dashboard Cite

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“…Female white whales become sexually mature at 4 to 7 yr of age and give birth to a single calf on average every third year thereafter (Brodie 1989). White whales are highly adapted to life in cold and icy waters; they possess a blubber layer that can be up to 15 cm thick (O'CorryCrowe 2002) and constitutes up to 40% of their total body mass (Sergeant & Brodie 1969). They lack a dorsal fin, but they do have a dorsal ridge that they can use to break through thin ice.…”

Section: Introductionmentioning

confidence: 99%

Transfer of fatty acids from mothers to their calves during lactation in white whales Delphinapterus leucas

Birkeland¹,

Kovacs²,

Lydersen³

et al. 2005

Mar. Ecol. Prog. Ser.

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Blubber biopsies, through the entire blubber layer, were collected from the members of 4 mother-calf pairs of white whales Delphinapterus leucas from Storfjorden, Svalbard, Norway. In addition, milk samples were collected from all 4 adult females. The calves ranged in age/size from newborn (with the umbilical cord still attached; 140 cm in length) up to a 1 yr old (body length of 255 cm). Since white whale calves consume only milk during their first year of life, free-living mother-calf pairs provide an interesting opportunity to study the deposition of lipids (calf blubber) when the diet (i.e. milk) is known precisely. The blubber of the newborn calves had fatty-acid (FA) compositions that differed significantly from the FA compositions of both the milk and the blubber of their respective mothers. The FA composition of the blubber of calves changed gradually with age, coming to resemble the FA composition of the blubber of their mothers more closely, rather than shifting towards the FA composition of the milk, i.e. their diet. The largest calf in the study had a blubber FA composition similar to that of the adult whales. Analyses also showed that the FA composition of the milk was significantly different from the FA composition of the maternal blubber.KEY WORDS: White whales · Fatty-acid composition · Lactation · Blubber · Milk Resale or republication not permitted without written consent of the publisher

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“…The name is derived from a Russian word Belukha, which means white, and it is gray at birth then the whole body turns white as it matures. The body size varies depending on the population, the smallest animals inhabit the Hudson Bay Canada, mid-sized in the eastern Canadian Arctic and the Gulf of St Lawrence with the largest being found off Greenland and the Sea of Okhotsk [5,19]. Belugas have been captured as an important source of food for native people, some of small and isolated populations are believed to be vulnerable as inbreeding and loss of genetic diversity might affect individual fitness and population viability in a changing environment [15].…”

mentioning

confidence: 99%

Circulating Testosterone and Inhibin Levels at Different Ages in the Male Beluga (<i>Delphinapterus leucas</i>)

Katsumata

Ueda

Arai

et al. 2012

The Journal of Veterinary Medical Science

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ABSTRACT. This study is the first report on circulating testosterone and inhibin levels in a species of whales, the beluga. Circulating testosterone and immunoreactive (ir-) inhibin levels in two captive male belugas ("Nack", originally from Canada and "Duke", from the Okhotsk Sea) were measured every month for 9 years between 1995 and 2003. Assuming that clearly increased testosterone levels in the circulation indicates that the belugas had reached sexual maturity, at the ages of 10 ("Nack") and 11 years old ("Duke"). Their testosterone levels before the significant increase (pre-pubertal) were 0.42  0.07 ng/ml (n=18) and 0.35  0.10 ng/ml (n=18) and, those of after the increase (maturity) were 1.65  0.14 ng/ml (n=74) and 2.06  0.14 ng/ml (n=74). Circulating ir-inhibin levels before sexual maturity were 0.78  0.04 ng/ml (n=18) and 0.64  0.04 ng/ml (n=15) and, after sexual maturity were 0.52  0.02 ng/ml (n=56) and 0.43  0.02 ng/ml (n=67). Seasonal changes were observed in the testosterone levels after sexual maturity and the levels increased during March and April in Canadian origin "Nack", and peaked in February in Okhotsk origin "Duke". Circulating ir-inhibin level gradually decreased as they aged. A negative correlation between the circulating testosterone and ir-inhibin was observed. No seasonal changes were observed in the ir-inhibin levels after sexual maturity. These data will surely correspond to clarification of endocrinology and the successful reproduction of the beluga.

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Body Size in White Whales, Delphinapterus leucas

Cited by 80 publications

References 0 publications

Quantifying the Sensitivity of Arctic Marine Mammals to Climate-Induced Habitat Change

Quantifying the Sensitivity of Arctic Marine Mammals to Climate-Induced Habitat Change

Transfer of fatty acids from mothers to their calves during lactation in white whales Delphinapterus leucas

Circulating Testosterone and Inhibin Levels at Different Ages in the Male Beluga (<i>Delphinapterus leucas</i>)

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