Cuellar et al.: Reproductive seasonality, maturation, fecundity, and spawning frequency of the vermilion snapper 



643 



Hf 





~\ Slage 1 

 zfy Stage 2 

 fjj\J\j Slage 3 (AYO) 

 &8|j] Slage4(MNO) 



I Stage 5 (HO) 



it 10 - 



01 02 03 04 05 06 



Oocyte diameter (mm) 



Figure 4 



Oocyte size-frequency (percent) distributions and oocyte 

 stage of three mature vermilion snapper representing the 

 developmental sequence of maturation. Females were col- 

 lected in May and length range was 192 mm to 213 mm 

 FL. (? = stages that were not counted.) 



Fecundity 



Location of oocytes within the ovary revealed no sig- 

 nificant effect on oocyte density (Table 8). Advanced 

 yolked oocytes (AYO's) were randomly distributed 

 within the ovary; samples could be taken from any 

 location within the ovary without bias. 



The relationship between ovary-free body weight 

 (OFWT) and potential fecundity (PF) was expressed 

 by the following equation: 



PF = -25,992 + (508 x OFWT). 



The coefficient of determination (r 2 ) was 0.583 for 

 the 13 fish used in the analysis (Fig. 10). The PF 



ranged from 17,374 to 122,130 oocytes for an OFWT 

 range of 109 g to 265 g. 



Monthly mean TF estimates of vermilion snapper 

 increased from 54,100 oocytes in May (/? = 16, OFWT 

 range 109-194 g) to 118,500 in August (re=25, OFWT 

 range 108-442 g); then decreased to 58,200 in Sep- 

 tember (« = 15, OFWT range 106-238 g). Analysis of 

 covariance of monthly equations of TF on OFWT in- 

 dicated that equations were similar over the spawn- 

 ing season (Fig. 11). The slopes of the equations were 

 similar (^=0.02984, df=4,85, P>0.25) and, assuming 

 a common slope, there was no significant difference 

 in intercepts between months (F=0. 02936, df=4,89, 

 P>0.25). Regression of TF on OFWT for days elapsed 

 since 15 April indicated that the coefficient for 

 elapsed days was not significant (<*=1.338, df=94, 

 P=0.1842). Thus, TF did not decline continually over 

 the spawning season. 



In whole oocyte samples used to estimate fecun- 

 dity, the average fraction of AYO's that were atretic 

 was 0.011 (SD=± 0.023, n=138). Minor alpha atresia 

 of AYO's was observed in 29% of the fish used in fe- 

 cundity estimates. A stepwise multiple regression of 

 OFWT, days, and atretic fraction of AYO's on TF, in- 

 dicated that the coefficient for the atretic fraction of 

 AYO's was not significant and thus atresia does not 

 result in a significant loss of oocytes (Table 9). 



