Females are capable of having a calf every two years and pregnancy lasts for over eleven months.
Young humpback calves are born with their eyes open and with good hearing. A newly born young calf has to be brought to the surface to breath because the stimulus for opening its blowhole is air and without air in its lungs, the calf would tend to sink. At birth the calf weighs approximately 680 kgs and is just over 4m in length. At birth calves have a coating of fine hair-like down which shines silvery or golden in the sun. Its usually replaced by the normal black and white pigmentation within a week.