BROWN-PETERSON ET AL.: REPRODUCTIVE BIOLOGY OF THE SPOTTED SEATROUT 



mature gonads were considered sexually mature. 

 The microscopic criteria used were similar to 

 those described by Yamamoto (1956), Hyder 

 (1969), and Macer (1974). The percentages of each 

 stage of oocyte, atretic structures, and postovula- 

 tory follicles were determined from histological 

 slides of the ovaries of females >305 mm SL by 



lected fields of view. An oocyte was counted if 

 >50% of the cell was in the field of view. Two 

 hundred and fifty to 500 oocytes were counted for 

 each histological specimen. 



A small portion of tissue (<0.5 g) was removed 

 from the center of each ovary of females >305 mm 

 SL collected in 1984 and 1985, placed in clearing 



slides of the ovaries of females >305 mm SL by SL collected in 1984 and 1985, placed in clearing 

 counting all the oocytes in three randomly se- solution (6 parts ethanol, 3 parts formalin, 1 part 



Table 1 . — Criteria used to describe gonadal reproductive stages of male and female spotted seatrout collected in South Texas. 



Stage 



Sex 



Macroscopic appearance 



Microscopic appearance 



Immature 



Regressed 



Mature 



Ripe 



Running 

 ripe or 

 spawning 



Partially 

 spent 



Spent 



F Ovary small, thin, light pink, slight vasculariza- 



tion. GSI range: 0.39-0.55. 



M Testes small, thin, light grey, appearance similar to 

 mesentery. 



F Ovary small, light pink, vascularization more obvious 



than in immature fish. GSI range: 0.39-1.16. 



Testes small, thin, white, slightly larger than imma- 

 ture fish. GSI range: 0.04-0.20. 



Ovary similar to regressed fish but slightly 

 larger. GSI range: 0.80-1.26. 



Testes similar to regressed fish but slightly 

 larger. GSI range: 0.16-0.48. 



Ovary visably enlarged, light yellow, highly vascular, 

 approximately 60% of the length of the body cav- 

 ity. GSI range: 0.95-2.6. 



M Testes thickened, creamy white, no free milt ex- 

 pelled when cut. GSI range: 0.21-0.68. 



F Ovary large, brilliant yellow orange, oocytes visible 



to naked eye, vascularization prominent. Ovaries 

 80-90% length of body cavity. GSI range: 2.5- 

 9.6. 



M Testes creamy white, thicker, more firm and elon- 

 gated than developing testes. A small amount of 

 milt expelled when cut. GSI range: 0.54-1.42. 



F Oocytes hydrated, ovary looks clear, takes up al- 

 most entire body cavity, highly vascular- 

 ized. GSI range: 12.5-19.9. 



M Testes white, swollen, milt does not flow with light 

 pressure, but flows freely when cut. GSI range: 

 1.07-1.62. 



F Hydrated oocytes expelled with little to no pressure, 



ovary fluid, fills almost entire body cavity. GSI 

 range: 7.7-17.6. 



M Testes creamy white, milt freely flowing with slight 

 pressure. GSI range: 1.41-3.84. 



F Ovary looks similar to mature condition but more 



flacid; occupies smaller percentage of body cav- 

 ity. GSI range: 2.0-5.3. 



M Tests looks the same as running ripe but 

 smaller. GSI range: 0.85-1.77. 



F Ovary flacid but still highly vasculahzed, no longer 



than 50% of body cavity, pinkish in color. GSI 

 range: 1.33-2.63. 



M Testes flacid, width reduced, white. GSI range: 

 0.13-0.80. 



Only primary oocytes present; no atretic oocytes. 



Lamellar margin thin. 

 Only primary spermatogonia present. 



Primary chromatin nucleolar and early perinuceolar 

 stage oocytes. Some atretic oocytes. Lamellar 

 margin thicker than immature, more convoluted. 



Primary and secondary spermatogonia present. 



Appearance of late perinucleolar oocytes and ph- 

 mary cortical alveoli stage oocytes. No atretic 

 oocytes present. 



Many secondary spermatogonia and primary sper- 

 matocytes. 



Oocytes in secondary cortical alveolar stage and 

 yolk granule stage. Many oocytes still in primary 

 cortical alveolar stage. Early yolk globular stage 

 present. 



All stages of spermatogenesis present, with few pri- 

 mary spermatogonia and free spermatozoa. Pri- 

 mary and secondary spermatocytes predominate. 



Oocytes in yolk globular stage most common. Yolk 

 and oil globules begin to encroach on nucleus. 

 Largest oocytes range from 300 to 375 y.m. 



No primary spermatogonia present, some second- 

 ary spermatogonia. Secondary spermatocytes 

 and spermatids most numerous. Spermatozoa in 

 central lobules. 



Many hydrated oocytes, irregularly shaped, 

 eosinophilic. Other oocytes in yolk granular and 

 yolk globular stages. 



Spermatozoa, spermatids and secondary spermato- 

 cytes predominate. Few to no spermatogonia. 

 Central lobules filled with spermatozoa. 



Same as ripe ovaries but fewer hydrated oocytes. 

 Atretic and postovulatory follicles may be present. 



Same as ripe fish, but spermatozoa evident in sperm 

 ducts. 



Similar to mature ovary, except atretic oocytes in 

 several stages of degeneration always evident. 

 Postovulatory follicles occasionally present. 



No spermatogonia, few primary spermatoocytes. 

 Most active spermatogenesis in peripheral lob- 

 ules. Spermatozoa partially filling lobules and 

 abundant in sperm ducts. 



Massive atresia of all remaining vitellogenic oocytes. 

 Many primary and chromatin nucleolar oocytes 

 present. Lamellar membrane highly convoluted. 



Spermatozoa present in some lobules. Most lobules 

 small, with only primary and secondary sper- 

 matogonia. 



375 



