260 



Fishery Bulletin 103(2) 



L t = length of size class i; 

 L 50 = the length at which 50% of the fish are sexu- 

 ally mature (stage 4+>; and 

 A = the width of the ogive. 



The ogive was fitted by minimizing the negative log-like- 

 lihood. Differences in male and female L 50 and a were 

 tested by using a ratio test that minimizes the binomial 

 log-likelihood of the form 



:ln 



Pi 



I- Pi) 



+ n t xlnd-p, ) + ln 



where n = the number of samples in size class i\ and 

 m t = the number of mature fish in size class i. 



Spawning frequency was estimated by using daily 

 proportions of ovaries containing early postovulatory 

 follicles (POFs), hereafter referred to as the spawn- 



Table 1 (continued) 



Stage 



Macroscopic 



Microscopic 



3 Active male 



4 Developing female 



4 Developing male 



5 Ripe female 



5 Ripe male 



6 Ripe, running female 



6 Ripe, running male 



7 Spent female 



7 Spent male 



Testes wider and triangular in cross 

 section. 



Ovary larger and orange-yellow in color. 

 Eggs clearly discernible. Veins and arter- 

 ies large and plentiful. 



Testes wider and deeper, creamy white in 

 colour, obvious presence of sperm in main 

 sperm duct. 



Ovaries are large in diameter, may have 

 a few hydrated eggs. Yellow oocytes take 

 up all the space. Veins and arteries large 

 and plentiful. 



Sperm present in main sperm duct and 

 in tissue. Gonad soft and breaks when 

 lightly pinched. 



Ovary amber in colour. Large with sub- 

 stantial proportion of gonad with hy- 

 drated eggs, which fill the lumen. Veins 

 and arteries large and plentiful. 



Free-flowing sperm extruded from fish 

 when the abdomen is lightly squeezed. 

 Testes very delicate and break easily when 

 handled. Copious amounts of sperm pres- 

 ent in main sperm duct and in tissue. 



Ovary reduced in size similar to stage-2 

 flaccid ovary. Few yolked oocytes remain- 

 ing. Ovary bloodshot. 



Testes white in color, smal 

 and bloodshot. 



shrivelled. 



The seminal vesicles expand and become filled with 

 spermatogonia. 



Yolk vesicles are common and primary yolk oocytes 

 begin to appear, which are characterized by the for- 

 mation of small spherical yolk granules. 



The seminiferous tubules of the testes are filled with 

 spermatozoa, which are also present in the primary 

 sperm duct. 



Tertiary yolk oocytes, characteriszed by large yolk 

 plates, appear along with primary yolk and yolk 

 vesicles. The nucleus becomes irregular in shape and 

 smaller in size. The nucleus migrates to the animal 

 pole of the cell after which hydration begins, result- 

 ing in increased transparency of the cells and an 

 increase in cell size. 



The seminiferous tubules expand with copious 

 amounts of spermatozoa that fill the lumen of the 

 primary sperm duct. 



Filled with hydrated oocytes. Due to dehydration 

 during the histological preparation, these oocytes 

 appear as collapsed bags. Hydrated oocytes may 

 squash and reshape the immature oocytes that sur- 

 round them. 



The seminiferous tubules of the testes appear dis- 

 tended and are filled with mature spermatozoa as is 

 the lumen of the primary sperm duct. 



Cells in various stages of atresia, and some hydrated 

 and mature oocytes may be present in the tissue. 



The seminiferous tubules are no longer distended 

 and have thicker walls than stage-6 tubules. They 

 contain few spermatozoa, which are present in the 

 lumen of the primary sperm duct. Large blood ves- 

 sels are apparent in the tissue. 



