Age determination of pond smelt using otolith phase
1994
Katayama, S. (Tohoku Univ., Sendai (Japan). Faculty of Agriculture) | Kawasaki, T.
As a part of study to clarify the population structure of the pond smelt, Hypomesus transpacificus nippoensis McAllister, the validity of method using the otolith phase for age determination of the fish is examined in this study. Opaque zones and translucent zones of the otolith are formed sequentially. In Lake Ogawara and off Hachinohe, the opaque zones are formed in December-July, the translucent zones are formed in August-November. Eggs of the fish in the lake usually hatch out around early May. Therefore the fish that have formed a second translucent zone of their otolith are estimated to be 1 year old. Moreover, this method can be applied to fish from other lakes, and would in general be useful for the fish inhabiting various geographical conditions. The relationship between otolith phase and life record is examined. The length of the opaque core, after complete formation, is proportional to the body length from August to October and is considered to correspond to the early stage growth. The otolith phase would be useful for analyzing the difference in past growth of subpopulation of the fish
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