Marine and Freshwater Behaviour and Physiology (2006)

DOI: 10.1080/10236240600563396


To provide hormone evidence on reproductive seasonality and maturity of the Yangtze finless porpoise, the authors monitored the monthly variations of serum reproductive hormones of a male Yangtze finless porpoise in captivity via radioimmunoassay from 1997 to 2003. It was demonstrated that the immature animal had a serum T level of 28–101 ng dL−1 (65 ± 52 ng dL−1), reached puberty with the serum T concentration ranging between 250 and 590 ng dL−1 (390 ± 130 ng dL−1), and attained reproductive maturity when the serum T level went beyond 1120 ± 180 ng dL−1 in the breeding season. The body length growth of the animal showed a pattern similar to the serum T variations during its adolescent period from the age of 4 to 6 years. Moreover, the serum T concentration of the male porpoise exhibited significant seasonal variations, indicating that its breeding season may start as early as March and end as late as September.