Abstract
Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is a critically endangered freshwater cetacean dwelling in the Yangtze River and its adjoining lakes. Affected mainly by the various anthropogenic activities in this region, its population decreased dramatically in the past two decades. To protect this animal from extinction, captive breeding program is an important way to provide basic knowledge for wild population conservation. Non-invasive fecal steroid radioimmunoassay technique was validated in three captive Yangtze finless porpoises for the first time in this study. The seasonality of one captive male and the reproductive status of two females were investigated by longitudinal monitoring their fecal reproductive steroid hormone metabolites. Pregnancy could be diagnosed by an abrupt increase in fecal progesterone metabolites. In late pregnancy (4 months before birth), a significant decrease of fecal progesterone metabolites was observed, which might be referenced for the expectation of parturition date. Seven estrous cycles were recognized in one breeding season of a non-pregnant female judged by the variation of fecal progesterone metabolite levels. The fecal progesterone metabolite level was proved a reliable and precise indicator for estrus and pregnancy diagnosis.
Highlights
The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is a critically endangered [1] freshwater subspecies of Neophocaena, which lives only in the middle and lower reaches of the Yangtze River and its appended big lakes [2]
In order to protect this animal from extinction like the baiji, and preserve the genetic diversity in captivity, a captive breeding program has been launched since the early 1990s by the Institute of Hydrobiology of the Chinese Academy of Sciences
Three calves have been born in this captive group since 2005, which presents the first reproductive success of freshwater cetacean in captivity [7]. This program provides a unique opportunity to promote our understandings on biology, reproductive physiology of this critically endangered cetacean
Summary
The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is a critically endangered [1] freshwater subspecies of Neophocaena, which lives only in the middle and lower reaches of the Yangtze River and its appended big lakes [2]. With the increasing anthropogenic impacts on this subspecies, its population dropped quickly in the past two decades. Three calves have been born in this captive group since 2005, which presents the first reproductive success of freshwater cetacean in captivity [7]. This program provides a unique opportunity to promote our understandings on biology, reproductive physiology of this critically endangered cetacean. By monthly monitoring of the serum hormones, Chen et al [8] found that Yangtze finless porpoises (YFPs) are obvious seasonal breeders. It is difficult to monitor the ovarian cycles and hormone dynamics in females through this monthly blood sampling regime because of the complicated variations of the reproductive hormones in females
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