The present study, the first to examine breeding ability in elderly cetaceans, addressed the reproductive capacity of four captive male Indo-Pacific bottlenose dolphins that are among the oldest in the world (47–50 years in 2017). The dolphins' reproductive ability was assessed by monthly monitoring of serum testosterone (T) levels over nine years (2009–2017), and examination of semen characteristics. Serum T concentrations from blood samples were measured by fluorescence immunoassay. The dolphins showed regular peaks in their serum T levels every year or once every few years. The mean monthly T level showed a significant seasonal change, beginning to elevate in January, peaking from March to May, and then declining until September. Semen production was confirmed in three of the four individuals, and semen quality was confirmed for those dolphins through collections one or two times a month for a year. The sperm concentration in samples from those individuals was comparatively high. These data indicated that the dolphins had the capacity to breed every year. Indo-Pacific bottlenose dolphins are capable of surviving to older ages in captivity than they typically reach in the wild, and it is likely that even elderly individuals retain their breeding ability.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 44 • No. 2