Studies on Resources of Isaki, Parapristipoma trilineatum-I

Age Determination and Growth

Abstract

With an aim to know the age and growth of isaki Parapristipoma trilineatum (THUNBERG), a scale analysis has been done on the 157 specimens mostly taken from waters near Miura peninsula, Kanagawa Prefecture during 1964-'66. For this analysis, a shadowgraph was used. Resting zones found on the scale were marked on scale-cards and then the distance of these zones were measured.
The major findings of the present study are summarized as follows. The resting zones in question seemed to be formed twice a year, one in winter (January to February), and the other in summer (June to August). An anti-Lee-phenomenon was observed. For the growth of the fish, the von BERTALANFFY's formulae were estimated as
lt=32.9[1-e^{-0.31(t+0.496)}], wt=579[1-e^{-0.31(t+0.496)}]^3.135
However, the curve did not fit to the growth of fish up to six-month-old. Hence a curve was infered for this stage as shown by a dotted line in Fig. 5. The calculated fork length at ages I-IV are given as follows: 12.2, 17.8, 21.8, 24.7cm, respectively.