Growth and Reproductive Activity of a Captive Female Harbour Porpoise (Phocoena phocoena) from Japanese Water

摘要

This report describes growth and annual reproductive cycle of female harbour porpoise (Phocoena phocoena) rescued from Japanese water in 2007. The maximum body length was 179 cm and body weight was 69.8 kg. The average daily food consumption was 7.0 kg (ranging 3.7 - 9.9 kg), 11.8% of the body weight. In this report, the porpoise was kept in 17 °C water annually and the blubber thicknesses showed almost constant throughout the year (average 18 mm, range 13 - 22 mm). Therefore, we added new evidence to this hypothesis by showing that body weight and the blubber thickness do not fluctuate seasonally in fixed water temperature. Serum progesterone level of the female showed five peaks from September to November, and each cycle lasted the average of 20.5 days. Such result indicates that harbour porpoise exhibits seasonal polyestrous activity.