Gestation lasts 10-11 months. Single calf is born November-March in North Atlantic, mainly late May and early June in Southern Hemisphere. Young are weaned in 6 months or less. Adult females produce one calf every 1-2 years. Most sources give the age of sexual maturity as 6-7 years or 7-8 years, but 2 years or mean of 6-15 years also has been reported; age of maturity apparently decreases when populations are significantly reduced. Maximum age is about 30-40 years in the North Atlantic, something less than 50 years in the Southern Hemisphere.