Present address: Otsuchi Marine Research Center, Ocean Research Institute, University of Tokyo, Otsuchi, Iwate 028–11, Japan.
LIFE HISTORY OF FRASER'S DOLPHIN, LAGENODELPHIS HOSEI, BASED ON A SCHOOL CAPTURED OFF THE PACIFIC COAST OF JAPAN
Article first published online: 26 AUG 2006
Marine Mammal Science
Volume 12, Issue 2, pages 199–214, April 1996
How to Cite
AMANO, M., Miyazaki, N. and Yanagisawa, F. (1996), LIFE HISTORY OF FRASER'S DOLPHIN, LAGENODELPHIS HOSEI, BASED ON A SCHOOL CAPTURED OFF THE PACIFIC COAST OF JAPAN. Marine Mammal Science, 12: 199–214. doi: 10.1111/j.1748-7692.1996.tb00571.x
We gratefully acknowledge E. Honma of Waseda University and T. Saiga and other staff of the Taiji Whale Museum for their help with sampling. H. Kaino and other fishermen of the Taiji dolphin hunting team and the Taiji Fishermen's Union kindly allowed us to examine the dolphins. K. Aida and M. Yoshioka of the University of Tokyo furnished facilities for histological study. A. Amaha helped us with laboratory procedures and T. Miyashita gave us information on sighting surveys. We thank T. Kasuya, W. F. Perrin, and two anonymous referees for comments that improved the manuscript. This study was partially supported by Grants-in-Aid from the Japan Ministry of Education, Science and Culture and the Japan Society for the Promotion of Science to MA.
- Issue published online: 26 AUG 2006
- Article first published online: 26 AUG 2006
- Received: 23 January 1995 Accepted: 25 May 1995
- Fraser's dolphin;
- Lagenodelphis hosei;
- life history;
- school composition;
- sexual dimorphism;
Life history of Fraser's dolphin, a little known delphinid species, was examined based on 108 specimens from a school captured by the driving fishing method in Japan. The sex ratio was approximately 1:1, and mature dolphins of both sexes formed the bulk of the school. The oldest animals were two males and a female of 17.5 yr. Age and body length at sexual maturity were estimated at 7–10 yr and 220–230 cm in males and 5–8 yr and 210–220 cm in females. Mature males were larger in body length than mature females and showed apparent secondary sexual features: deepening of the tail stock and widening and darkening of the lateral dark stripe. The annual ovulation rate was 0.49. The estimated neonatal length (110 cm) predicts a gestation period of about 12.5 mo and calving peaks in spring and probably also in fall. The calving interval was estimated to be about 2 yr. These life history parameters are similar to those of the striped and pantropical spotted dolphins, except for longevity. The reproductive rate of this species may be lower than that of other pelagic delphinids, if the observed shorter longevity is real.