AGE AND GROWTH OF THE LABRID FISH HALICHOERES-POECILOPTERUS IN AGO BAY, CENTRAL JAPAN

The present report deals with the age and growth of the wrasse Halichoeres poecilopterus (Pisces: Labridae) in relation to sex types (primary male, female, and secondary male) examined by scale reading, based on fish taken from Ago Bay, Mie Prefecture, Japan from July 1977 to August 1985. The scale removed from the ventrolateral portion of the trunk was the most suitable for age determination, and the ring marks on it were clearly distinguishable. Examination of marginal increments of scale showed that the ring marks formed once a year from January to March. The relationship between standard length (SL, mm) and body weight (W, g) was expressed by the formula: log 10 W=3.15 log10, SL-5.00. There were no significant differences in the mean back-calculated lengths at the time of each ring formation between primary males and hermaphroditic individuals (females and secondary males). The growth curves for length and weight were described as follows: L(t)=211(1-exp (-0.224(t+1.049))); W(t)=210(1-exp (-0.224(t+1.049)))3.15; where L(t)=standard length at age t; W(t)=body weight at age t. The sex change from females to secondary males in hermaphroditic individuals took place mostly at age 4 or older. The larger females have a stronger tendency to change to secondary males in a certain age group.