周防灘産メイタガレイの年令と成長

概要

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For the studies of age and growth of finespotted flounder (Pleuronichthys cornutus, TEMMINCK et SCHLEGEL), age determination was carried out by counting the number of zones in the otolith from 12, 314 specimens caught in Suõ-nada area of Seto Inland Sea from October 1980 to October 1984.On the basis of the monthly changes of the appearance rate of hyaline zone at the margin of the otolith of 3, 268 specimens, hyaline zone is found once a year during the months from August to March, mainly December. The spawning season extends from November through December. Therefore, spawning roughly coincides in time with formation of hyaline zone, and the mean standard body length at the zone formation may be concluded as that at each full year of age.As the above mentioned results, each male and female finespotted flounder grows 109, 108mm in standard body length at one year of age, 131, 139mm in that at two years of age, 140, 154mm in that at three years of age, 146, 162mm in that at four years of age, and 149, 168mm in that at five years of age, respectively.No difference in growth of finespotted flounder is found between sexes until one year of age, however, female grows faster than male on and after one year of age.The age determination based on the otolith zones of finespotted flounder on and after five years of age is considerably difficult because of the difficulty of discrimination of opaque and hyaline zones in the otolith.
日本水産學會の論文