Thermal Significance of the Topographical Distribution of Blubber in Ringed Seals (Phoca hispida)

Ryg, Morten; Smith, Thomas G.; Øritsland, Nils Are

doi:10.1139/f88-121

Cited by 109 publications

(91 citation statements)

References 4 publications

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“…In a study of the topographical distribution of blubber in ringed seals, Ryg et al (1988) found that the ratio of blubber thickness to body radius was nearly constant over the body, thereby maximising the blubber available for insulation. The hind part of the body had a higher thickness to radius ratio and was therefore considered to ..jLength/ Mass· blubber thickness be "over-insulated".…”

Section: Thermoregulationmentioning

confidence: 99%

Status and biology of ringed seals (Phoca hispida) in Svalbard

Lydersen

1998

NAMMCOSP

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The ringed seal is the most abundant mammal in the Svalbard area. Annual pup production in this area is estimated to be 20,000. No systematic harvest records exist, but some few hundred seals are t*en annually, mainly for dog food. The ringed seals in Svalbard are protected from hunting in the period 15 March -15 April. Peak pupping season is the first week of April. New-born ringed seals weigh an aven~ge of 4.6kg. They are nursed for about 39 days, and weaned at an average body mass of around 22kg. During the period of maternal care pups consume a total of about 54 litres of milk, that is composed of approximately 38% fat and 10% protein. Asymptotic standard lengths and body masses for adult ringed seal males and females are 131.5 and 127.8cm, and 52.6 and 59.9kg, respectively. The maximum values recorded for lengths of males and females in Svalbard are 157cm and 107kg, respectively. There is marked seasonal variation in body mass in both sexes with the highest mass records being recorded in early spring before pupping occurs, and with minimum values in the summer after the breeding and moulting seasons. The observed variation in mass is mainly due to changing blubber thickness of the seals. Ringed seal males attain sexual maturity at the age of 5 -7 years, while females reach maturity when they are 3-5 years of age. The oldest seal collected in Svalbard was aged 45. Ringed seals in the Svalbard area feed on a variety of prey organisms, the most important of which are polar cod (Boreogadus saida) and the crustaceans Parathemisto libellula, Thysanoessa inermis and Pandalus borealis. Ringed seal pups start diving during the nursing period while they are still white-coats, and spend about 50% of the time in the water prior to weaning. They are capable of diving for up to 12min and dive to the bottom of the study areas (max. 89m). Nursing females spend more than 80% of their time in the water. Maximum recorded dive duration for mothers was 21.2min. In order to produce a weaned pup, the net energy expenditure for a ringed seal mother is 1,073MJ. This energy value corresponds to the consumption of 185kg of polar cod or 282kg of P. libellula. The annual gross energy consumption for adult males and females is calculated to be 5,600MJ and 7,300MJ, respectively. The main predators of ringed seals in Svalbard are polar bears (Ursus maritimus) and Arctic foxes (Alopex lagopus). In addition, both glaucous gulls (Larus hyperboreus) and walruses (Odobenus rosmarus) are documented as predators of ringed seals in this area. Heavy predation pressure is probably the main factor explaining why pups of this species start diving at such a young age, why they have access to so many breathing holes (8.7 on average) and why they keep their white coat long after its thermoregulatory properties have vanished. Pollution levels in ringed seals from Svalbard are, generally speaking, similar to levels in other areas of the Arctic.

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Section: Thermoregulationmentioning

confidence: 99%

Status and biology of ringed seals (Phoca hispida) in Svalbard

Lydersen

1998

NAMMCOSP

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“…A cylindrical model, illustrated in Fig. 1, has also been supposed by other authors (Ryg et al, 1988;Lavigne et al, 1990;Watts et al, 1993).…”

Section: The Modelmentioning

confidence: 69%

“…Different models have been used to estimate heat exchange in marine mammals (Innes, 1986;Kshatriya & Blake, 1988;Ryg et al, 1988;Hokkanen, 1990;Watts et al, 1993), but the results vary widely, which is probably explained by the practical difficulties entailed in measuring body surface temperature of these animals. This paper presents an iterative method of predicting the skin temperature of cetaceans using deep body temperature, swimming speed, and the temperature and thermodynamic properties of the water.…”

Section: Introductionmentioning

confidence: 99%

Assessment of body surface temperature in cetaceans: an iterative approach

Silva

2004

Braz. J. Biol.

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Heat transfer from skin surface to ambient water is probably the most important aspect of thermal balance in marine mammals, but the respective calculations depend on knowing the surface temperature (T S ), the direct measurement of which in free animals is very difficult. An indirect iterative method is proposed for T S prediction in free cetaceans from deep body temperature, swimming speed, and temperature and thermodynamic properties of the water.Key words: cetaceans, thermoregulation, skin temperature, prediction. RESUMO Determinação da temperatura cutânea em cetáceos: uma abordagem iterativaA transferência de energia térmica da superfície corporal para a água é provavelmente o aspecto mais importante do equilíbrio térmico em mamíferos marinhos, mas os respectivos cálculos dependem do conhecimento da temperatura da superfície, T S , cuja medição direta em animais em liberdade constitui um problema difícil de resolver. Um método iterativo é proposto para a predição de T S de cetáceos em liberdade, a partir da temperatura corporal profunda, da velocidade de deslocamento e da temperatura e propriedades termodinâmicas da água.Palavras-chave: cetáceos, termorregulação, temperatura cutânea, predição.

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“…Blubber thickness was measured to the nearest mm at a point dorsally, located 60% of the length along a straight line from the tip of the nose. The blubber thickness at this point has been shown to be highly sensitive to changes in body condition in ringed seals (Phoca hispida; Ryg et al 1988) and harp seals (Phoca groenlandica; Beck et al 1993). Canine teeth from the upper or lower jaws were taken for age determination.…”

Section: Methodsmentioning

confidence: 99%

“…Seasonal variation in the condition of adult bearded seals was analyzed based on blubber thickness measurements (Ryg et al 1988) and by using a condition index (CI) (American Society of Mammalogists 1967):…”

Section: Methodsmentioning

confidence: 99%

Growth, age at sexual maturity and condition in bearded seals ( Erignathus barbatus ) from Svalbard, Norway

et al. 1999

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The aim of this study was to describe growth, determine age at sexual maturity and investigate the condition of bearded seals (Erignathus barbatus) collected in the fjords of Spitsbergen, Svalbard, Norway. Morphometric data, teeth and sex organs were collected from 110 animals. Age was determined by reading the cementum layers in hard longitudinal sections of canine teeth. Sexual maturity in males was determined according to the size of the testes and bacula. Females were de®ned as being sexually mature according to ®ndings of mature follicles or corpora lutea/albicantia. Von Bertalan y growth curves were applied to both standard length and body mass, and asymptotic values for males and females were 231.1 11.4 cm and 269.9 26.2 kg, and 233

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Thermal Significance of the Topographical Distribution of Blubber in Ringed Seals (Phoca hispida)

Cited by 109 publications

References 4 publications

Status and biology of ringed seals (<i>Phoca hispida</i>) in Svalbard

Status and biology of ringed seals (<i>Phoca hispida</i>) in Svalbard

Assessment of body surface temperature in cetaceans: an iterative approach

Growth, age at sexual maturity and condition in bearded seals ( Erignathus barbatus ) from Svalbard, Norway

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