The reproductive organs of males and females are similar to those of humans, but are tucked away inside the animal so as not to provide added resistance as they move through the water. On the breeding grounds, calves are born and females and males engage in mating behavior. After this period is over, they migrate back to the cooler waters to feed.
Different species have different mating strategies.
Most whales practice polygeny, one male mates with many females during a breeding season. This way, the male can ensure his genetic material will be passed on to the next generation. There are variations on this theme. For example, male humpback whales sing a song during the breeding season in order to attract females. The right whale engages in sperm competition where one female will mate with a number of males, one right after the other.