North Atlantic right whale with calf (Eubalaena glacialis). Right whales are large baleen whales. Adults are generally between 45 and 55 feet (13.7-16.7 m) long. Females give birth to their first calf at an average age of 9-10 years. Gestation lasts approximately 1 year. Most winter off the southeastern United States and head North for summer feeding and nursery grounds off New England and farther North. Credit: NOAA