Reproduction in female Atlantic walruses (Odobenus rosmarus rosmarus) from north-west Greenland
Reproduction in female Atlantic walruses (Odobenus rosmarus rosmarus) from north-west Greenland
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DOI：
10.1017/s0952836901001236
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发表时间：
2001-10-01
影响因子：
2
通讯作者：
Born, EW
中科院分区：
文献类型：
--
作者：
Born, EW
对152只雌性大西洋海象的生殖道进行了分析。这些材料是在1977- 1978年（n = 44）和1988- 1991年（n = 108）的1月19日至11月19日期间从格陵兰西北部（即巴芬湾北方北水冰间湖东部）因纽特人的生计狩猎中收集的。76%的海象性成熟。在1月19日至6月25日期间发现了发情期雌性动物（n = 23）。根据卵巢解剖学，雌性动物在发情期间可能排卵多次，但卵巢解剖学不能用于确定个体是否怀孕。最年轻的雌性海象已经生育了5岁，这表明一些雌性海象在4岁时就性成熟了。最大的未成熟雌性是8岁，第一次排卵的最大动物是11岁。生殖道中与生殖器相关的生长表明，性成熟在6至8岁之间达到。根据93例个体（0-12岁）的生殖史，达到性成熟（即首次排卵）的平均年龄为6.1岁（95% CI：5.2-7.1岁）。在5月至11月期间收集的81只成熟雌性中，34.6%怀孕，43.2%产后，22.2%不活动。这些比例与假设三年生殖周期的模型没有什么不同。胎儿长度和质量随时间的增长表明着床分别发生在6月29日至7月11日或6月26日至7月5日之间。根据对28名新生儿的观察，平均出生日期为6月20日（范围为2月4日至11月11日）。
The reproductive tracts of 152 female Atlantic walruses Odobenus rosmarus rosmarus were analysed. The material was collected between 19 January and 19 November in 1977-78 (n = 44) and 1988-91 (n = 108) from the subsistence hunt by Inuit in north-west Greenland (i.e. in the eastern parts of the North Water polynya in northern Baffin Bay). Seventy-six per cent of the walruses were sexually mature. Oestrus females (n = 23) were found between 19 January and 25 June. Based upon ovarian anatomy, females may ovulate several times during oestrus but ovarian anatomy could not be used to determine if an individual was pregnant. The youngest female that had given birth was 5 Years old, indicating that some female Atlantic walruses become sexually mature at 4 year's of age. The oldest immature female was 8 years old, and the oldest animal that ovulated for the first time was 11 years. Age-related growth in the reproductive tract indicated that sexual maturity was reached between 6 and 8 years of age. Based on reproductive history of 93 individuals (0-12 years old) the average age of attainment of sexual maturity (i.e. first ovulation) was 6.1 years (95% Cl: 5.2-7.1 years). Of 81 mature females collected during May-November, 34.6% were pregnant, 43.2% postpartum and 22.2% inactive. These proportions did not differ from a model assuming a triennial reproductive cycle. Growth in foetal length and mass with time indicated that implantation occurred between 29 June and 11 July or between 26 June and 5 July, respectively. Mean birth date based on observations of 28 newborns was 20 June (range 4 February- 11 November).