During the mating season right whales aggregate into mating groups,
where numerous males compete for access to a receptive female. A
female will mate with several males making the actual competition on a
sperm level inside the female.
Female southern right whales
become sexually mature at the age of 7 – 10 years (when they are around
12,5m long).
The age of sexual maturity in males is not known. Gestation is about 12
months and the newborn calf is about 4 - 6m long.
Southern right whales
have only one calf which is weaned at about 1 year and roughly 8m long.
Mother-calf pair splits after one year when arriving again on the
breeding grounds. From there on the mother has one year of rest.
Female reproductive (inter-calf) intervals of three years are found to
be most common, with intervals of two, four or more years being detected
much less frequently. Right whales may have a life expectancy of around
70 years, although this figure is not at all certain.