Reproduction in short-beaked common dolphins (Delphinus delphis) from the western North Atlantic
Reproduction in short-beaked common dolphins (Delphinus delphis) from the western North Atlantic
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北大西洋西部短喙海豚（Delphinus delphis）的繁殖
DOI：
10.1007/s00227-006-0394-1
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发表时间：
2007
期刊：
影响因子：
2.4
通讯作者：
A. Read
中科院分区：
文献类型：
--
作者：
A. Westgate;A. Read
短喙海豚（Delphinus delphis Linnaeus）的单一种群分布在从佛罗里达州到纽芬兰岛的北大西洋西部。 1989 年至 1998 年间在旗鱼流网捕捞中被杀死的海豚为本研究提供了样本。这些与从搁浅计划中收集的尸体的额外观察结果相结合。对 74 只雌性和 161 只雄性短喙海豚进行了样本检查。兼捕和搁浅样本的性别比例中存在高度显着的男性偏差，这表明该种群中存在基于性别的栖息地划分或学校隔离。根据牙齿和睾丸的脱钙薄切片估算年龄，并对卵巢样本进行宏观和微观检查。分析表明，繁殖既是季节性的，也是同步的。雌性在大约八岁时达到性成熟；雄性9.5岁时性成熟。受孕发生在 7 月和 8 月（平均 7 月 24 日）。妊娠期估计持续不到一年，因此大多数雌性在 7 月和 8 月（平均 7 月 15 日）分娩。年怀孕率估计在 25% 至 33% 之间。男性的睾丸质量季节性增加五倍，曲细精管直径增加两倍。七月份观察到了精子生产潜力的峰值。繁殖季节结束时，睾丸大小和活动在八月后下降。据推测，该种群中的雄性海豚会进行某种形式的精子竞争。
A single population of short-beaked common dolphins (Delphinus delphis Linnaeus) occurs in the western North Atlantic from Florida to Newfoundland. Dolphins killed in a swordfish driftnet fishery between 1989 and 1998 provided samples for the present study. These were combined with additional observations from carcasses collected from stranding programs. Samples were examined from 74 female and 161 male short-beaked common dolphins. A highly significant male bias in the sex ratio of both the bycatch and stranding samples suggests that sex-based habitat partitioning or school segregation occurs in this population. Age was estimated from decalcified thin sections of teeth and testis and ovarian samples were examined both macro- and microscopically. Analyses showed that reproduction was both seasonal and synchronized. Females reached sexual maturation at approximately age eight; males matured at 9.5 years. Conception occurred during July and August (mean day 24 July). Gestation was estimated to last just under a year, so most females gave birth during July and August (mean day 15 July). Annual pregnancy rate was estimated to be between 25 and 33%. Males undergo a fivefold seasonal increase in testes mass and a twofold increase in seminiferous tubule diameter. Peak sperm production potential was observed in July. At the end of the breeding season testis size and activity decreased after August. Male dolphins in this population are hypothesized to engage in some form of sperm competition.