Abstract
In the present paper, the age and growth of butter fish, Psenopsis anomala (TEMMINK and SCHELEGEL), in the Kii Channel, are estimated based on size composition and on otoliths and ring marks on scales covered by the pectoral fin.
During the period from July in 1970 to April in 1972, 995 specimens were collected. Among those, scales from 510 specimens and otoliths from 203 specimens were observed and measured by a shadowgraph.
The results are summarized as follows:
1) The annual ring marks on scale are formed once a year in the spawning season from April to July.
2) The growth at the young stage is very rapid. However, the growth rate decreases when a length of about 130mm in body length is reached. This slowing down of growth rate is observed in autumn.
3) Since the change of the growth process in the early days, the growth equations for more than one age in length and weight are given as follows,
BLt=243.2{1-e-0.34(t+1.674)}, BWt=486.7{1-e-0.34(t+1.674)}2.8912
The body lengths at the age of 1-4 are calculated as 145.2, 173.5, 193.6 and 207.9mm respectively.
