Abstract

The serum progesterone level (P level) for pregnancy of bottlenose dolphins (Tursiops truncatus) and observation of nursing were analyzed. Our facility was established in 2001 in Palau, the north latitude seven degrees in a tropical rain zone, open ocean pool. Average water temperature is 29 centigrade all around the year.

Serum samples were obtained from five captive adult female bottlenose dolphins (age: 12–16, length: 263–284 cm) through five years (2009–2014). Blood samples were centrifuged and kept in freezer as a serum. The samples were checked by Tottori University. Concentration of the progesterone was measured by enzyme immunoassay (Spotchem Vidas SV-5010, Sysmex bioMerieux, Tokyo, Japan).

Three dolphins gave birth twice and one dolphin gave birth once for the time being. Delivered date was concentrated from August to December. Total of seven calves were born.

Delivery date was expected by the P level and the body temperature and pregnancy diagnoses were done by the P level (over 3.0 g/ml, every two weeks and 3 times collection periodically).^1,3 However, the P levels were 1.1–28.4 ng/ml during pregnancy. The P levels of 1.0–3.0 ng/ml were classified as indeterminate.²

One dolphin was diagnosed pseudopregnancy (2012.9 death).³ P level was 7.59–22.69 ng/ml in eight months, then decreased to 0.4 ng/ml. Afterward it increased to 6.27–25.15 ng/ml in seven months again; nevertheless there were no miscarriages. That dolphin was dead 4 months after second pseudopregnancy and a CL-like structure was found at the autopsy.

Behavior, appetite, and body temperature were checked (twice a day) to find out the delivery date. The body temperature goes down approximately 1 centigrade in 24 hours before delivery. However, it went down only -0.3–0.8 centigrade.⁴

Moreover, nursing behavior had differences according to the mother's trained situation, parity and learning of other dolphin's nursing observation. The nursing training was carried out after 1st calf died due to lack of nursing. Additionally, before September 2010, the calves had hit their body and rostrum to the net surrounded pool. Therefore, the pool was expanded for nursing easily and the dolphins nursed well after that. As of January 2015, most of the adult female dolphins were parity and a year survival rate of the calves have increased every year.

To improve accuracy of monitoring pregnancy, the P level checked by urine and feces samples daily is available.^5,9 Another step of obtaining detailed reproductive data is ultrasound.^6-8 It is useful to diagnose pseudopregnancy and expect delivery day correctly. Preventive measure of accidents should be done for increasing survival rate of the calf.

Acknowledgements

This report would not be possible without the efforts from the trainers and Takashi Kamio, DVM, at Dolphins Pacific as well as the support of the management staffs and owners. Progesterone assay were performed by Laboratory of Theriogenology, Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University.

* Presenting author

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