The Effects of Growth on Sexual Maturation in Sockeye Salmon

抄録

In order to examine the effects of growth on sexual maturation in sockeye salmon, Oncorhynchus nerka, smolts were marked with PIT tags and reared in an aquarium filled with seawater from May (age-1) to October (age-2). Their fork lengths were individually tracked every four or five months throughout the experiment. At the end of the experiment, 10 females and 13 males matured while 7 females and 3 males remained immature. Distinct differences in the fork lengths of mature and immature fish were observed from August and December at age-1. In particular, the immature group showed extremely low growth during this period. This result suggests that low autumn growth can inhibit the onset of sexual maturation in this species.