[Return to Article]

Fig. 26. Diagrammatic representation of the lifecycle of masu salmon (Oncorhynchus masou) (modified the figure by Kiso 1995). There seems to be a sequential diversity in migratory patterns among representative non-migratory (precocious parr) and migratory (smolt) forms. In masu salmon, 1+ parr that occupy focal foraging areas (territory), exhibit precociously sexual maturation, and have high plasma sex steroid levels become representative non-migrants, precocious parr. In contrast, some of the 1+ immature fish that could not gain focal territories become representative migrants, smolt migrants. Their migratory patterns seem to be modulated in an inhibitory fashion by their maturity and/or growth performance (see text for details). Note that the "poor growth fish" which does not differentiate into either precocious parr or smolt migrants during the age of 1+ appears to differentiate into non-migratory parr or migratory smolts in another year, mainly during the age of 2+.

[Return to Article]

Copyright © TERRAPUB