Scales

被覆部: coated area 隆起線が同心円状: concentric ridges 露出部: exposed

（海水移行）チェック: (seawater migration) check

1歳魚: 1 years fish 2歳魚: 2 years fish 3歳魚: 3 years fish 4歳魚: 4 years fish

Ridges become denser in winter, forming annual zones (dormant or winter zones).

Usually, scales collected during the spawning run are observed, so the full age of the fish is used.

(Add 1 year in the fall and winter when fertilized and hatched)