GREELEY ET AL.: STRIPED MULLET OVARY 



frequency profile from an ovary in this stage is 

 shown in Figure 6. GSIs of females with stage I 

 ovaries ranged up to 0.8. 



Stage II (early vitellogenesis) is characterized by 

 recruitment of previtellogenic oocytes into vitello- 

 genesis. A single clutch of vitellogenic oocytes starts 

 to form, becoming distinct from the remaining mass 

 of previtellogenic oocytes as the recruited oocytes 

 increase in diameter due to yolk accumulation. This 

 stage can be further divided into two substages on 

 the basis of the appearance of the profiles. In stage 

 Ila, recruitment into vitellogenesis has just begun; 

 a clear separation between the developing (vitello- 

 genic) and nondeveloping (previtellogenic) oocytes 

 is not yet discernible. In stage lib, the developing 

 clutch forms a distinct peak (or peaks) as recruit- 

 ment and subsequent vitellogenic growth continues. 

 LODs of females with stage II ranged from 0.18 to 

 0.56 mm; GSIs varied from 0.3 to 8.5. 



In stage III (mid- to late-vitellogenesis), recruit- 

 ment into vitellogenesis ceases, although oocytes in 

 the recruited clutch continue to increase in diam- 

 eter due to further yolk accumulation. This stage 

 can also be divided into two substages. In stage Ilia, 

 recruitment has just ended: the recruited clutch is 

 spread out in size, and multiple size-frequency peaks 

 are apparent. In stage Illb, the recruited clutch 

 tightens into a single peak; oocyte diameters con- 

 tinue to increase. LODs of females with stage III 

 ovaries varied from 0.40 to 0.59 mm; GSIs ranged 

 from 2.1 to 12.1. 



In stage IV (prespawning), oocytes in the re- 

 cruited clutch reach the minimum prematuration 

 size of 0.60 mm in diameter and become capable of 

 resuming maturation in response to a hormonal 

 signal. Late in the stage, as shown in Figure 6, all 

 oocytes in an ovary will be at, or above, the mini- 

 mum prematuration size. LODs of females with 

 stage IV ovaries were 0.60 and 0.72 mm; GSIs were 

 more scattered, from a low of 11.4 to a high of 21.2. 



Stage V (spawning: not shown) is characterized 

 by the presence in the ovary of maturing oocytes 

 or mature eggs. No fish with ovaries in this stage 

 were caught in the Inlet; however, this stage was 

 produced in the laboratory by injection of human 

 chorionic gonadotropin into prespawning females 

 (Greeley et al. 1986b). 



Stage VI (postspawn) ovaries, upon gross exam- 

 ination, are small, red, and flaccid in appearance 

 with a thickened ovarian wall. Spawning is ap- 

 parently complete— at least by the time the females 

 return to the Inlet— as no partially spawned ovaries 

 were collected, nor were large atretic oocytes or 

 eggs ever observed. LODs of postspawn females 



were 0.12 to 0.14 mm; GSIs ranged from 0.1 to 

 1.6. 



Monthly changes in the relative frequency of these 

 stages in females collected from Matanzas Inlet dur- 

 ing ovarian recrudescence in 1985-86 are shown in 

 Figure 7. The variation in these stages is similar to 

 the variation observed in the LOD, although the 

 ovarian stages provide a somewhat different infor- 



o 

 o 



o 



>- 

 o 



LU 



O 

 LU 



q: 



100 

 50H 





 100- 



50- 





 lOOi 



^ 50- 





 100 



50- 





 lOO-i 



50 





 00 



50H 







I 



m 



\ \ 



 



i 



T r 



i 



Y7^ 



-\ r 



^ P R ^ F?^ 



i 



^ i?^ r^ ^ 



^ , ^ I 



r^ r- 



Jan 

 n = 6 



Aug 

 n = l9 



Sep 

 n = 52 



Oct 

 n = 36 



Nov 

 n = 22 



_Ep. 



Dec 

 n = 22 



I 



1 1 1 r 



I n n EI 2 3Z[ 



OVARY STAGE 

 (1985-1986) 



Figure 7.— Monthly variation in ovarian stages of adult 

 Mugil cephalus (>20 cm SL) during prespawning ovarian 

 recrudescence along the northeast Florida coast. Data pre- 

 sented for the 1985-86 season only (see text). 



195 



