Reproduction Fishers reach sexual maturity from 1-2 years of age. Both sexes are predominantly solitary except during the breeding season, which occurs in the beginning of March. Gestation lasts about 51 weeks. The gestation period is long because the fertilized egg is delayed several months before implanting on the uterine wall. An average size litter of three young are born from late February through April in dens situated high in hollow trees.
Females mate almost immediately after giving birth, and are therefore pregnant most of the time.
Life Cycle Young are born blind and helpless, but after four weeks are able to eat meat. At about 7 weeks their eyes open, and they begin to walk at approximately 9 weeks. The female may move her young several times to alternate dens. By 17 to 18 weeks, they are weaned and ready to leave the den. Except for raising young, fishers normally do not have a permanent den.