Baculum and testes of the hooded seal (Cystophora cristata): growth and size-scaling and their relationships to sexual selection

1999 ◽  
Vol 77 (3) ◽  
pp. 470-479 ◽  
Author(s):  
Edward H Miller ◽  
Ian L Jones ◽  
Garry B Stenson
Keyword(s):  
Sexual Selection ◽  
Body Length ◽  
Harp Seal ◽  
Sexual Competition ◽  
Hooded Seal ◽  
Size Scaling ◽  
Cystophora Cristata ◽  
Pagophilus Groenlandicus ◽  
Testicular Size ◽  
Older Males

Growth and size-scaling of the baculum and testes in the moderately polygynous hooded seal (Cystophora cristata) were studied using 107 specimens of known age (1 month to 28 years) from the northwestern Atlantic. Bacular growth was rapid between 2 and 5 years of age: length increased 150% and "density" (i.e., mass/length) increased 8-fold and mass 20-fold. Growth continued throughout life. In large, old (>14 years) males, the baculum averaged 20.7 cm in length, 2.1 g/cm in density, and 44.4 g in mass. Bacular length increased relative to body length until seals were about 5 years of age, after which it averaged 8.2%. Testicular growth continued until the seals were about 12 years of age. Testes from breeding males >12 years old averaged 11.2 cm in length, 4.6 cm in width, and 138 g in mass; length averaged 4.9% of body length. In males 2-5 years of age, bacular and testicular sizes were positively allometric relative to body length; in older males, bacular mass and density were positively allometric, and bacular length and testicular size isometric, relative to body length. Bacular size was mostly positively allometric relative to testicular size (bacular length exhibited some isometry). Compared with that of the related and ecologically similar harp seal (Pagophilus groenlandicus), which is presumed to have a promiscuous mating system, the baculum of the hooded seal was structurally simpler and grew more quickly but reached a relatively smaller size in adults (8.2 vs. 9.9% of body length). Relative testicular length was also smaller (4.9 vs. 5.7% of body length) and bacular density lower (2.1 vs. 2.8 g/cm) than in the harp seal. These observations suggest that intra- or inter-sexual competition via copulation is weaker in the hooded seal.

scholarly journals First independent feeding of harp seal (Phoca groenlandica) and hooded seal (Cystophora cristata) pups in the Greenland Sea

2000 ◽  
Vol 2 ◽  
pp. 29 ◽  
Author(s):  
Tore Haug ◽  
Kjell T Nilssen ◽  
Lotta Lindblom
Keyword(s):  
Interspecific Competition ◽  
Niche Overlap ◽  
Harp Seal ◽  
Minor Importance ◽  
Greenland Sea ◽  
The West ◽  
Hooded Seal ◽  
Cystophora Cristata ◽  
Phoca Groenlandica

Data were collected from harp seal (Phoca groenlandica) and hooded seal (Cystophora cristata) pups belonging to the Greenland Sea (or "West Ice") stocks in 1995-1997. Pups of both species were observed to feed independently shortly after weaning, and their first food was almost exclusively crustaceans. Parathemisto sp., particularly P. libellula, dominated the diet of both the harp and the hooded seal pups, but the diet also contained sympagic amphipods of the genus Gammarus. Krill (Thysanoessa sp.) was of minor importance as food for seal pups in 1995, but occurred more frequentlyin the diet of both species in 1996 and 1997. Considerable niche overlap may suggest some interspecific competition between harp and hooded seal pups in the West Ice.

Nutritional composition of blubber and meat of hooded seal (Cystophora cristata) and harp seal (Phagophilus groenlandicus) from Greenland

2006 ◽  
Vol 96 (4) ◽  
pp. 524-531 ◽  
Author(s):  
Linn Anne Brunborg ◽  
Kåre Julshamn ◽  
Ragnar Nortvedt ◽  
Livar Frøyland
Keyword(s):  
Nutritional Composition ◽  
Harp Seal ◽  
Hooded Seal ◽  
Cystophora Cristata

Evidence of polygyny from spatial patterns of hooded seals (Cystophora cristata)

1988 ◽  
Vol 66 (3) ◽  
pp. 703-706 ◽  
Author(s):  
Daryl J. Boness ◽  
W. Don Bowen ◽  
Olav T. Oftedal
Keyword(s):  
Body Length ◽  
Cluster Size ◽  
Nearest Neighbor ◽  
Spatial Dispersion ◽  
Single Male ◽  
Hooded Seal ◽  
Cystophora Cristata ◽  
Ice Floes ◽  
Nearest Neighbor Distances ◽  
Original Female

Based on scant empirical data, the mating system of the hooded seal (Cystophora cristata) has been variously characterized as monogamous or polygynous. To evaluate the hypothesis that female hooded seals are clustered to a degree that would facilitate polygyny, we collected data on the spatial dispersion of female and male seals on the ice floes off the Labrador coast. While flying from a ship at the edge of the seal herd to a study site within the herd, we recorded each sighting of female seals as a "solitary female" or a "cluster of females" (using an approximate 10 body length radius to differentiate these conditions). The numbers of males near females were also recorded. Nearest-neighbor distances were obtained during on-ice transects. The frequency of nearest-female-neighbor distance classes peaked at 6–10 seal body lengths (one body length = 1.9–2.6 m) and then declined to distances of greater than 25 body lengths. About 40% of 357 females with pups (or 22% of 279 sightings of seals) were in clusters consisting of two or more mother–pup pairs; the maximal cluster size observed was five. The majority of females or clusters of females had a single male in attendance (54% of 245 sightings). Females in the central part of the herd were both clustered and attended by males more often than were females at the periphery. Observations of a few marked males suggested that some took up positions near additional females when their original female companions departed. These results are consistent with the hypothesis that the spatial pattern of hooded seals should facilitate polygyny.

scholarly journals The gastric properties of free-ranging harp (Pagophilus groenlandicus (Erxleben, 1777)) and hooded (Cystophora cristata (Erxleben, 1777)) seals

2004 ◽  
Vol 61 (2) ◽  
pp. 287-292 ◽  
Author(s):  
Jørgen S. Christiansen ◽  
Asbjørn Gildberg ◽  
Kjell T. Nilssen ◽  
Charlotta Lindblom ◽  
Tore Haug
Keyword(s):  
Trophic Relationships ◽  
Feeding Mode ◽  
Hooded Seal ◽  
Mean Values ◽  
Cystophora Cristata ◽  
Pagophilus Groenlandicus ◽  
Individual Variations ◽  
Species Specific ◽  
Stomach Weight ◽  
Free Ranging

Abstract The study of trophic relationships in seals is based primarily on prey remains recovered from the digestive tract or scats. Basic data on the gastric properties of seals are scarce and are considered to be important to interpret data from dietary studies of these animals. Hence, we examined the key properties of the gastric chyme post mortem (i.e. temperature, acidity, and the concentration of the proteolytic enzyme pepsin) in free-ranging harp (Pagophilus groenlandicus, n=40) and hooded (Cystophora cristata, n=41) seals. Seals displayed huge inter-individual variations in their gastric properties with ranges in temperature: 23.9–37.9°C, acidity: pH 1.16–7.34, and pepsin concentration: 11–1059 μg ml−1 chyme. The stomach weight and the mean values of gastric parameters revealed, however, significant species-specific differences. The stomach weight relative to body weight of hooded seal exceeded that of harp seal (t=13.77, d.f.=75, p<0.001). Furthermore, the gastric temperature and pepsin concentration were lower for harp (32.8°C and 75 μg ml−1) compared to that for hooded (35.3°C and 344 μg ml−1) seal. The reason for this disparity may be linked to the feeding mode and diet composition displayed by these seal species.

scholarly journals Vitamin E and vitamin A contents, fatty acid profiles, and gross composition of harp and hooded seal milk through lactation

1999 ◽  
Vol 77 (6) ◽  
pp. 952-958 ◽  
Author(s):  
C Debier ◽  
K M Kovacs ◽  
C Lydersen ◽  
E Mignolet ◽  
Y Larondelle
Keyword(s):  
Fatty Acid ◽  
Vitamin E ◽  
Vitamin A ◽  
Harp Seal ◽  
Milk Lipid ◽  
Lactation Period ◽  
Fatty Acid Profiles ◽  
Milk Fatty Acids ◽  
Hooded Seal ◽  
Cystophora Cristata

This study reports fatty acid profiles and vitamin A and vitamin E contents of the milk of the harp seal (Phoca groenlandica) and hooded seal (Cystophora cristata) throughout the lactation period, as well as standard compositional analyses. The milk for this study was collected from harp and hooded seals breeding on the pack ice in the Gulf of St. Lawrence. Mother-pup pairs were serially captured, or point-sampled, in order to obtain milk samples during different lactation stages. Milk lipids showed the respective species' typical patterns during lactation, with a significant increase for harp seal milk and a relatively constant value for hooded seal milk. The profiles of most of the milk fatty acids remained relatively stable over the course of lactation in both species. Vitamin A content was also quite stable through lactation. By contrast, vitamin E content underwent a dramatic drop between the day of birth and early lactation for harp seals and from birth to midlactation for hooded seals. It then continued to decrease at a slower rate until the end of lactation in both species. The highest vitamin E content of colostrum reached 125 mg/kg of milk for harp seals and 200 mg/kg of milk for hooded seals. These concentrations subsequently dropped to 20-50 mg/kg of milk by early or mid lactation. These changes in this lipophilic, antioxidizing vitamin were not correlated with milk lipid content or its polyunsaturated fatty acid profiles.

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