Reproduction in the male Cape fur seal Arctocephalus pusillus pusillus: age at puberty and annual cycle of the testis

Stewardson, CL; Bester, M. N.; Oosthuizen, W. H.

doi:10.1017/s095283699800908x

Cited by 3 publications

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“…The timing also corresponds to the accumulation of fat; as the fur seals get fatter, their metabolic rate increases ( Beck et al ., 2003 ). As we were unable to measure the fur seals year round, the exact timing of this phenomenon is unknown, although it is likely to be consistent with the onset of spermatogenesis for males, which begins 3–4 months before the breeding season ( Stewardson et al ., 1998 ; Stewardson, 2007 ). Spermatogenesis is energetically expensive, particularly for large mammals with low metabolic rates ( Gomendio et al ., 2011 ).…”

Section: Discussionmentioning

confidence: 99%

Intrinsic and extrinsic influences on standard metabolic rates of three species of Australian otariid

Ladds

Slip

Harcourt

2017

Conservation Physiology

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Section: Discussionmentioning

confidence: 99%

Intrinsic and extrinsic influences on standard metabolic rates of three species of Australian otariid

Ladds

Slip

Harcourt

2017

Conservation Physiology

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“…The histology of reproduction and a general description of the reproductive cycle has been done •for the male (Stewardson et al 1998) as well as the female Cape fur seal (Rand 1955), though the latter study was done in the absence of an accurate ageing technique. Vital population parameters, such as age of puberty, age of sexual maturity, age specific fecundity rates and age-and sex-specific survival rates require a reliable way of assigning ages to seals .…”

Section: List Ofmentioning

confidence: 99%

Seasonal changes in the ovarian structure ofthe Cape fur seal, Arctocephalus pusillus pusillus

Odendaal¹,

Bester²,

Merwe³

et al. 2002

Aust. J. Zool.

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The annual reproductive cycle of the female Cape fur seal (Arctocephalus pusillus pusillus) was described by noting monthly gross changes in ovaries from 159 females, histological changes in 46 females and placental scars in 119 females. The size and weight of an ovary containing a corpus luteum was significantly greater than that of an ovary containing a corpus albicans for most of the year, the latter only approaching, or exceeding the former during the breeding season. Follicular activity initially increased in ovaries containing either a corpus luteum or a corpus albicans; however, it declined in the ovary containing a corpus luteum after implantation, while in that containing a corpus albicans it increased, reaching a maximum in December of 32.0 ± 10.08 follicles, averaging 5.41 ± 0.73 mm. The corpus luteum increased in size following ovulation, attaining a maximum size of 22.28 ± 3.38 mm in August (eight months after ovulation). Thereafter, it gradually decreased in size, generally becoming invisible to the naked eye by 30–32 months after ovulation. Luteal cells increased until seven months after ovulation, reaching a maximum size of 34.36 ± 1.26 μm before regressing, disappearing from the corpus luteum by 18 months after ovulation. Using placental scarring and CA counts in 119 females, a pregnancy rate of 77.4% was calculated, with 6.5% abortions and 16.1% non-implantations making up the remainder.

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BACULAR AND TESTICULAR GROWTH AND ALLOMETRY IN THE CAPE FUR SEALARCTOCEPHALUS P. PUSILLUS(OTARIIDAE)

Oosthuizen¹,

Miller

2000

Marine Mammal Science

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The baculum in Arctocephalus p. pusillus reaches up to 14.1 cm in length, 13.5 g in mass, and 1.3 g/cm in density (= mass/length). A pubertal growth spurt occurs between 2 and 3 yr of age, when bacular length increases by 28%, mass by 124%, and density by 77%; concurrently, body length increases by 14%. A second, weaker spurt occurs at social maturity (9‐10 yr of age). Testes grow most rapidly between 1 and 2 yr of age, when testicular length increases by 29%. After 3 yr of age, growth in bacular and testicular length slows, and bacular mass continues to increase approximately linearly. Bacular and testicular lengths average 6.8% and 3.4% (respectively) of body length in adults, compared with 9.9% and 5.7% in the promiscuous harp seal (Pagophilus groenlandicus). Bacular length, mass, and density, and testicular length, are positively allometric to body length over growth; bacular length is isometric to testicular length. Among animals of the same age, bacular length and mass are positively allometric to body length in young animals, with negative allometry or isometry thereafter; testicular length is isometric to body length in young animals and negatively allometric thereafter. Patterns of early growth and allometry of the baculum and testes are interpreted as adaptations for mating opportunities, years before territoriality is possible. The baculum and testes of adult Cape fur seals and other otariids are small compared with those of most phocids, because sperm competition among male otariids is weak.

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Reproduction in the male Cape fur seal Arctocephalus pusillus pusillus: age at puberty and annual cycle of the testis

Cited by 3 publications

References 0 publications

Intrinsic and extrinsic influences on standard metabolic rates of three species of Australian otariid

Intrinsic and extrinsic influences on standard metabolic rates of three species of Australian otariid

Seasonal changes in the ovarian structure ofthe Cape fur seal, Arctocephalus pusillus pusillus

BACULAR AND TESTICULAR GROWTH AND ALLOMETRY IN THE CAPE FUR SEALARCTOCEPHALUS P. PUSILLUS(OTARIIDAE)

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