ROSS and MERRINER: REPRODUCTIVE BIOLOGY OF BLUELINE TILEFISH 



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North Carolina 

 South Carolina 



Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec 

 Months 



FIGURE 6. — Monthly mean gonad index values for male and female 

 ( 'aulnlatilux micropn from North Carolina and South Carolina, mean 

 bottom temperatures off Beaufort, N.C. (Stefansson and Atkinson 

 1967), and photoperiod. 



regression and early development. Ripe females were 

 captured off South Carolina during April and July, 

 which could indicate a more continuous or three- 

 peaked spawning season. Monthly mean GSI as well 

 as mean standard length were greater for females off 

 South Carolina, but data are too limited to draw any 

 further conclusions. 



Analysis of ova development within individual 

 ovaries suggested that blueline tilefish are multiple 

 spawners (Fig. 8). Ovaries considered Resting 

 characteristically contained primary oocytes and 

 previtellogenic oocytes. Early-Developing ovaries 

 showed a progression of early vitellogenic oocytes 

 developing from the residual stock. Well-Developed 

 ovaries in late April contained a mode of late 

 vitellogenic oocytes cooccurring with previtellogenic 



Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec 

 Months 



Figure 7. — Percent frequency histogram of gonad developmental 

 stages observed each month for female Caulolatilus microps from 

 North Carolina and South Carolina. 



and early vitellogenic oocytes (Fig. 9). Ripe females 

 from May and June exhibited modes of pre- 

 vitellogenic oocytes, early vitellogenic oocytes, late 

 vitellogenic oocytes, and mature eggs. This indicated 

 continuous development from the residual stock of 

 oocytes occurred when spawning was imminent. 

 Early vitellogenic ova are predominant in Spent- 

 Redeveloping ovaries and cooccur with residual 

 mature, atretic mature, and late vitellogenic oocytes. 

 Late vitellogenic oocytes were again the predomi- 

 nant oocytes in Well-Developed ovaries during Sep- 

 tember. There was also a decreased proportion of 

 early vitellogenic oocytes in comparison with Well- 

 Developed gonads from May. 



Males accommodate the protracted season of 

 oogenesis by maintaining a constant state of develop- 

 ment during the spawning season. The two peaks in 

 GSI of testes coincided with those observed for 

 ovaries (Fig. 6). Testes contained some spermatozoa 

 in all months sampled and observed histologically, 

 while those from April through September generally 

 contained large quantities of spermatozoa in the 

 collecting tubules. However, we never captured any 

 males with free-running milt. 



Fecundity 



We estimated the fecundity of blueline tilefish from 

 three periods during their spawning season. Fecundi- 

 ty ranged from 210,000 ova (412 mm TL) to 

 3,220,000 ova (637 mm TL) for 18 fish captured from 

 April to early June (Fig. 10). Fecundity was signi- 

 ficantly correlated with both length and weight: 



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