Abstract
Age and growth of the largemouth bass Micropterus salmoides in Lake Ono, Yamaguchi Prefecture, Japan were studied by otolith reading of 529 specimens. Otolith radius and ring radii were measured from the focus to the anterior edge and to outer margins of the hyaline zones, respectively. Ring marks were formed on the otoliths once a year from March to May. The number of ring marks indicated approximately the full age of the fish because the marks formed at the spawning period. The relationship between otolith radius and standard length (SL) was linear. The growth of this fish was expressed by the von Bertalanffy's equation as Lt=395.2 [1-exp {-0.340 (t+0.007)}] for females and Lt=380.4 [1-exp {-0.326 (t+0.031)}] for males; where Lt is SL in mm and t is age in years. Females grew slightly faster than males. The estimated maximum ages were 12 years old for females and 10 years old for males.
