104 



Fishery Bulletin 89(1), 1991 



> 



20 



10 



Immature 

 n=513 



50 



30 



10 



Maturing Virgin 

 n=614 



20n 



to 



Early Developing/Resting 

 n = 480 



10n 



Late Developing II 

 n=55 



Gravid 

 '1 n=37 



I , 



Ripe 



3 1 n = 9 



g Spawning/Spent 



20 60 100 140 



FORK LENGTH (mm) 



180 



Figure 2 



Length frequencies of immature and female Peprilus burti 

 by maturity stage (see Table 1). 



x 



a 



Q 

 < 



o 



C3 



30 

 26 

 2 2 

 1 8 

 14 

 10 

 06 

 2 



OCT 79 (F„| 



DEC 79 |F 78 .w 79 | 



. SEP 79 |F 79 | 

 NOV 79 |F 78 .W 79 | 



95 105 115 125 135 145 155 165 175 



FEMALE 



JAN 80 |W 79 .F 78 | 

 NOV 79 |F„| 



OCT 79 |F 78 | 



NOV 79 |W 7 ,| 



SEP 79 |F 78 | 



JON 79 IE 78 | 



APR 79 |F 78 | 



OCT 78 |W 7a | 



OCT 79 |W, 9 | 



95 105 115 125 135 145 155 165 175 



FORK LENGTH (mm) 



Figure 3 



Monthly gonad weight-length regressions for Peprilus burti 

 by cohort group (W = Winter, F = Fall). Line lengths show 

 observed size ranges. 



Figure 4 

 (facing page and overleaf) 



Monthly length frequencies of Peprilus burti off Freeport, Texas. 



Results 



Maturation and spawning periodicity 



Peprilus burti mature at 100-160 mm in length. Few- 

 fish larger than 100 mm were immature (Fig. 2). Males 

 were identifiable at 100-1 10 mm when the testes 

 became creamy white, but they were difficult to stage 

 macroscopically. Females were 95-155 mm and 105- 

 165 mm in Early Developing and Late Developing 

 stages, respectively. Most Gravid and Ripe females 

 were 120-150mm, the smallest being 113mm. These 

 sizes-at-maturity are supported by regressions of gonad 

 weight on fork length (Fig. 3) in which x-intercepts for 



both sexes usually were 95-1 10 mm during September 

 through February, a period that brackets much of the 

 broad spawning period when fish should be maturing. 

 Age compositions and sizes-at-age presented later in- 

 dicate P. burti mature to first spawn at 9-16 months. 



Peprilus burti spawn primarily during the broad 

 period of September through May. Fish 30-40 mm, 

 which occurred mid-November to early July (Fig. 4), 

 were 1.5 months of age April- July and mid-Novem- 

 ber-December based on quadratic regressions of size- 

 on-age for pooled Winter and Fall cohorts (Table 2). 



Little spawning of P. burti occurs June through 

 August. Fish 30-40 mm, 1.5 months-old, were not cap- 

 tured late July to early November (Fig. 4). No distinct, 



