FISHERY BULLETIN: VOL. 74, NO. 4 



of these indices were plotted monthly, to thus 

 indicate duration and peak of spawning, and age 

 and size at sexual maturity. The linear regressions 

 fecundity on length, weight, and age were cal- 

 culated based on mature (Stage 4) ovaries from 50 

 females (ages II-IX, 304 to 520 mm TL) collected 

 from January through March for the years 1973 

 and 1974. One ovary randomly selected from each 

 pair was blotted dry and weighed to the nearest 

 0.01 g. The selected ovary was crumbled and all 

 ovarian tissue removed. The eggs were then 

 filtered, blotted dry, and weighed. One sample 

 from each ovary of 0.2-0.4 g was weighed to the 

 nearest 0.001 g and placed in a 6 x 6 counting grid 

 and all ova were counted. The formula: 



(W,){w) 



was used to estimate the number of eggs in the 

 ovaries, where Y = total number of eggs in both 

 ovaries, W = weight of both ovaries, W^ = weight 

 of selected ovary, W^' = weight of ovary after 

 removal of ovarian tissue, iv = weight of sample, 

 and // = number of eggs in the sample (Lassiter 

 1962). 



RESULTS AND DISCUSSION 



Sexual Maturity 



Ovary condition progressed from ripe. Stage 4, 

 dominant from January through March, to 

 spawned. Stage 5, dominant from May through 

 June, indicating that peak spawning occurred in 

 March and April (Figure 1). Ovaries collected in 

 April and May were flaccid and showed resorption 

 of eggs. By June all of the fish were early matur- 

 ing. The ovaries gradually became more firm after 



Gonod Ind.. ( °°,"°t(T' * '°°) "=423 

 Gonod lnd«« I r* X 10 I N =242 



... I I I I I I 



SEPI OCT NOV DEC JAN FEB MAD API! MAT JUN JUl AUG 



Figure l.-Mean monthly gonad indices for female Pagrus 

 pagrus collected from Onslow Bay, N.C., 1972 to 1974. 



resorption in early summer and little change in 

 gonad condition was noted in late summer and 

 early fall. Maturation of ovaries occurred between 

 October and January. Stratification of the sexual 

 maturity data by month supported the hypothesis 

 of late winter to early spring spawning. Approx- 

 imately 23% of the fish examined in January were 

 late maturing and 77% were ripe. By February, 

 12.5% were classified as late maturing, and 87.5% 

 were ripe. The first spawned (Stage 5) fish were 

 collected in March and their frequency of occur- 

 rence increased to 60.5% in April (Figure 2). 

 Walker (1950) reported ripe P. pagrus in January 

 and February off North Carolina, and Ranzi (1969) 

 found that they were sexually mature from April 

 to June in the Mediterranean Sea off Algeria. 



Early maturing and ripe stages of males were 

 easily discernible by gross examination of the 

 testes, but the late maturing and ripe classes were 

 difficult to separate. Milt could be pressed from the 



100 

 80- 

 60- 

 40- 

 20- 

 



L 



^^. , 



Late Maturing, Stage 3 

 N = 31 



u 



Z 



LU 



Zi 

 O 



>- 

 u 



z 



UJ 



3 



o 



Ripe, Stage 4 

 N=77 



Spawned, Stage 5 

 N = 33 



Maturing , Stage 2 

 N=91 



MONTHS 



Figure 2.-Percentage of female red porgy at various stages of 

 sexual maturity, collected in Onslow and Raleigh bays, N.C., by 

 month. 



I 



776 



