Our criteria for evidence of sexual maturity were 

 based on a minimum egg diameter and a minimum 

 gonad index. Fish with maximum ova diameters 

 equal to or greater than 0.3 mm were considered 

 mature based on the work of Merrett (1970) who 

 considered eggs of this size as maturing, having 

 completed yolk and chorion formation. We some- 

 what conservatively chose GI = 1.0 as the other 

 criterion based on our data (Fig. 7 and 8) which show 



and II suggests that the latter is the case. Based on 

 these criteria first maturity of striped marlin oc- 

 curred in the 155-165 cm length classes and in the 

 160-165 cm length classes of sailfish (Fig. 7, 8,9, 10). 



Frequency of Spawning 



Simultaneous presence of both mature, non- 

 atretic ova in the lumen and developing ova in the 



+ + 



+ f t + + 



+u 



UIHHH+ 



ZIW 1 



U++M 



LENGTH GROUPS (cm) 



- 1 1 1 1 f~ 



i + 



+ + + 





«0- <90- ZOO- 210- 



LEHGTH GROUPS (cm) 



Figure 7. — Striped marlin gonad indices versus eye-fork 

 length groups presented in quarters of the year. Numbers 

 of striped marlin sampled are given in parentheses. 



Figure 8. — Sailfish gonad indices versus eye-fork length 

 groups presented in quarters of the year. Numbers of 

 sailfish sampled are given in parentheses. 



that no gonad index exceeded 1.0 in Quarter I and, 

 further, the gonad indices for immature fish below 

 145- 150 cm in Quarter II were remarkably consistent 

 and did not exceed 0.3. The increase in average 

 gonad index with increasing fish lengths between 1 50 

 and 190 cm in Quarter II suggests that larger fish 

 either mature earlier or have larger gonad index val- 

 ues at given maturity stages than smaller fish. The 

 presence of higher gonad indices for large fish in 

 Quarter I than those of small fish in both Quarters I 



follicles is possible evidence of multiple spawning. 

 However, lack of these conditions does not neces- 

 sarily rule out multiple spawning. We plotted ova 

 diameter frequency polygons of 300 ova from speci- 

 mens with the highest gonad indices in each 2-wk 

 period throughout 1969 and 1970. In addition, larger 

 numbers of eggs were measured for one striped mar- 

 lin and two sailfish, which had high gonad indices 

 (Fig. 11). We found no indication of multiple spawn- 

 ing. 



94 



