Refs in Life History section Fin sei and Bryde s are all baleen whales The cited sources mentioning those species give age at physical maturity 20 25 for Bryde s 25 for seis and 25 30 for fin whales iirc Evans gives age at sexual maturity duration of lactation and gestation etc for various species of baleen whale Rommel and Reynolds give the estimated length of minkes at weaning Go find the pages yourself