McDonough et al.: Fecundity and spawning season of Mugil cephalus 



825 



Table 1 



Histological criteria used to determine reproductive stage in female striped mullet {Mugil cephalus) once sexual differentiation has 

 occurred (Wenner et al.: see footnote 2 in the general text). 



Reproductive stage 



Description 



1. Immature 



2. Developing 



3. Running ripe 



4. Atretic or Spent 



5. Inactive or Resting 



Inactive ovary with previtellogenic oocytes and no evidence of atresia. Oocytes are < 80 ^m, lamellae 

 still contain somatic and connective tissue bundles. Ovary wall is very thin (one or two cell layers). 



Developing ovary have enlarged oocytes generally greater than 120 /jm in size. Cortical alveoli are 

 present and actual vitellogenesis occurs after oocytes reach 180 /jm in size and continue to increase 

 in size. Abundant yolk globules with oocytes reaching a size of >600 pm. 



Completion of yolk coalescence and hydration in most oocytes. 



More than 30% of developed oocytes undergoing the atretic process. 



Previtellogenic oocytes only but traces of atresia possible. In comparison to immature females, most 

 oocytes are >80 ^m, lamellae have some muscle and connective tissue bundles. Lamellae are larger, 

 have moore oocytes, and are elongated. A thicker ovarian wall with blood vessels, muscle, and nerve 

 tissue. 



were then teased apart. After separation, the oocytes were 

 spread out on a Bogorov tray and counts of ooc5ftes, greater 

 than 400 |jm, were made by using a dissecting microscope at 

 12x magnification. Each subsample was counted twice and 

 counts were averaged. A third count was performed if the 

 first two counts differed by more than 10%. Oocyte density 

 was calculated by dividing the mean number of oocytes by 

 the mean weight of all three subsamples for each specimen. 

 The oocyte density was then used to calculate the total 



oocyte number for each ovary, or individual fecundity, by 

 multiplying mean oocyte density by whole ovary weight. 



In order to determine mean oocyte diameter for each 

 specimen, 20-30 oocytes were removed from each counted 

 subsample and grouped together in a petri dish. Each oo- 

 cyte was then measured along the longest axis by using 

 Optimas''''^ Image Analysis software (version 6, Media 

 Cybernetics, Bothell,WA). Mean oocyte diameter was 

 calculated as the average of all measurements for each 



