Gestation may be about 16 months (Right Whale Recovery Team 1990) (also reported as 11-12 months and 13-14 months). Peak in calving apparently occurs from December through March off the southeastern U.S. (Right Whale Recovery Team 1990). Young nurse for at least 9 months (Right Whale Recovery Team 1990) (another report: weaned in 6-7 months). During their first year, calves accompany their mothers during the spring migration and summer feeding (Schaeff et al. 1993). Sexually mature in 5-9 years. Mean age of first parturition is 7.6 years (Knowlton et al. 1994). One calf is produced generally every 3-5 years.