Threeline Grunt Research Articles

The present report deals with the age and growth of threeline grunt Parapristipoma trilineatum (Pisces: Perciformes: Haemulidae) examined by otolith reading, based on 885 individuals taken from coastal areas of Kumanoa-nada (Kii Peninsula, central Japan) from March 1981 to July 1983. The otolith was failry large and was removed very easily from cranium. Hyaline and opaque zones were shown clearly without grinding nor sectioning. The otolith was more suitable for age determination of the fish than scale because ring marks were shown distinctly even for older specimens, and lack or duplication of ring marks were very few. Examination of marginal increment of otolith showed that the ring marks (outer margins of opanque zones) formed once a year in the spawning season (June and July). Range of length growth was estimated by mean values and standard deviations of calculated fork lengths at the time of each ring formation. As a result, average growth was expressed by the following equation as Lt=357.5(1-exp(-0.2855(t+0.2909))) and the growth for about 95% of the fish was within the limits of two equations as Lt=362.1(1-exp(-0.3377(t+0.3622))) and Lt=355.8(1-exp(-02427(t+0.1283)) (L, fork length in mm; t full age).

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