sport fishing boats in Honolulu, and C. hippurus 

 specimens were also obtained from cruises of the 

 NOAA ship Townsend Cromwell to the Northwestern 

 Hawaiian Islands from October 1976 to September 

 1981. Fork lengths were measured to the nearest 

 millimeter with calipers. The extraction and slide 

 preparation of sagittae, and counting method were 

 the same as described for the validation experiments 

 above But before reading the sagittae of fish caught 

 in the wild, the sagitta of a known-age fish was re- 

 examined to review the difference between known 

 daily increments and subdaily increments. Concen- 

 tric daily increments, which consist of an inner light 

 band and an outer dark band, were distinguished 

 from subdaily increments by carefully focusing to 

 the plane of maximum clarity. The dark band of the 

 subdaily increment appeared less defined than the 

 dark band of daily increments. Misinterpretation and 

 counting subdaily increments as daily increments 

 could result in an overestimation of aga The mean 

 of 10-20 counts was used as the age estimate of older 

 fish. 



Age estimates of wild fish were fitted to the von 

 Bertalanffy growth model using NLIN Procedure, 

 a nonlinear regression routine (SAS Institute 1982). 

 The three juvenile C. hippurus whose sex was un- 



determined were added to both the male and female 

 groups when fitting the curves. 



Results 



Validation 



Fertilized eggs of C. equiselis and C. hippurus 

 began to hatch after 48-50 h at 24°-25°C and all 

 hatched within 2 h. The larvae of both species were 

 4.0-4.6 mm TL and had two pairs of otoliths, the 

 sagitta and lapillus, at time of hatching. Otoliths of 

 C. equiselis and C. hippurus on D-0 ranged from 16 

 to 20 nm in diameter and consisted of the core and 

 primordium. An hour after hatching, the larvae were 

 from 5.2 to 5.4 mm TL but did not grow during the 

 next 3 d and even shrank from 0.1 to 0.2 mm. Oto- 

 liths of both species on D-l had a dark ring near the 

 edge which the otoliths of D-0 larvae did not have 

 and were 22-24 ^m in diameter. The sagittae of both 

 species on D-4 had four increments (Fig. 1) and were 

 now slightly larger than the lapillus. Sagittal 

 diameters were 29-36 fim for C. equiselis and 34-41 

 ^m for C. hippurus. 



Mean counts of growth increments on the sagit- 

 tae of 10 C. hippurus (Table 1) and 13 C. equiselis 



Figure 1— Sagitta of a day-4 Coryphaena hippurus larva. Diameter of sagitta is 17 ^m. 



188 



