Abstract
The validity of age determination of the Japanese charr Salvelinus leucomaenis using scale readings was examined by the mark and recapture method in a Japanese mountain stream from 1986 to 1989. When recaptured within a year, all of the 3 (1 growth and 2 resting) scale zone fish were found to still have 3 zones on their scales. One year after marking, they had 4 (2 growth and 2 resting) or 5 (3 growth and 2 resting) zones on their scales and after 2 years, they still had 4 or 5 zones. Fish with 1 resting zone, i.e., 1 annulus, were regarded as age 1+ and fish with 2 annuli were regarded as age 2+. Consequently, age determination of the Japanese charr using scales might be reliable to 1+ age but doubtful for 2+ and older.
