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



Table 3. — Percentage of female spotted seatrout In seven repro- 

 ductive stages by month, as assessed by histological and macro- 

 scopic examination of the ovaries. Data from April 1982 to May 

 1985 are combined. REG ^ Regressed, E DEV = Early Develop- 

 ing, DEV = Developing, MAT = Mature, RR = Ripe and Running 

 Ripe, P SP = Partially Spent, SP = Spent. 



tions: 150-190 (xm) varied from a lov^^ of 7.3% in 

 June to a late season high of 16.1%, and averaged 

 13% of the total number of oocytes in the ovary. 

 Yolk globular oocytes, the largest oocytes present 

 (diameter: 200-375 p.m), were most common. The 

 percentage of oocytes in the yolk globular stage 

 ranged from a high of 30.8% in April to an end-of- 

 season low of 22.6% in September and averaged 

 26.9% during the reproductive season. In addition 

 to the actively growing oocytes in the ovary, a 

 small percentage of atretic oocytes was always 

 found in fish with mature ovaries. Atretic oocytes 

 are defined here as vitellogenic oocytes undergo- 

 ing alpha stage atresia. The percentage of atretic 

 oocytes ranged from a low of 2.2% in March to a 

 midsummer high of 8% in July and averaged 

 5.4%. Additionally, postovulatory follicles (POF) 

 were observed in the ovaries offish captured from 



pletely spent fish were captured before July and 

 few were captured during the remainder of the 

 reproductive season. 



Histological observations offish with regressed 

 ovaries collected from late September to mid- 

 February showed only primary chromatin nucle- 

 olar and early perinucleolar oocytes. Atretic 

 oocytes were present from September until mid- 

 December; no atretic oocytes were observed from 

 mid-December through the end of February. The 

 appearance of late perinucleolar and primary cor- 

 tical alveoli stage oocytes in late January, Febru- 

 ary, and early March represented the initial 

 stages of ovarian recrudescence. Ovarian devel- 

 opment was proceeding rapidly by early March 

 and oocytes in the secondary cortical alveoli and 

 yolk granule stages were common. 



During the reproductive season, histological 

 observations of the ovary showed a heterogeneous 

 morphology. Oocytes in all stages of growth (from 

 resting to the fully grown yolk globular stage) 

 were distributed throughout the ovaries of all ma- 

 ture, running ripe, and partially spent fish col- 

 lected from March through the end of September. 

 Vitellogenesis was probably continuous from 

 February until the end of September, as shown by 

 the continual presence of large numbers of 

 oocytes in the cortical alveoli and yolk granule 

 stages. The relative percentages of three types of 

 post cortical alveolar stage oocytes in fish in the 

 mature reproductive stage did not change 

 markedly from March through the end of Septem- 

 ber (Fig. 4). The percentage of oocytes in the yolk 

 granule stage (diameter in histological prepara- 



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MONTH 



Figure 4. — Frequency of three different types of oocytes in fe- 

 male spotted seatrout ovaries in the mature reproductive stage 

 (MAT, Table 3) as assessed by histological observation. Fish 

 were collected from South Texas during the reproductive sea- 

 son. Frequency refers to the percentage of each type of oocyte 

 relative to the total number of all types of oocytes counted. Data 

 from April 1982 through the end of September 1983 are com- 

 bined and the number (A^) of individuals examined each month 

 is indicated. Bars indicate mean percentage of oocytes ±1 SE of 

 the mean. Yolk granule oocyte diameters ranged from 150 to 

 190 p-m, and yolk globule oocyte diameters ranged from 200 to 

 375 fim in histological preparations. Atretic oocytes are defined 

 here as oocytes in alpha stage atresia. 



379 



