Murphy and Chittenden: Reproduction, age and growth, and movements of Pepnlus bum 



1 I 



n = 32,332 



< 



60 LU 



60 80 100 120 140 160 180 200 220 240 

 TOTAL LENGTH (mm) 

 60 80 100 120 140 160 180 



FORK LENGTH (mm) 



Figure 9 



Length-frequency and cumulative percentage of Peprilus burti 

 off Freeport, Texas. 



the Late Developing and Ripe stages when sizes formed 

 a plateau (Fig. 2). In contrast, growth of Winter and 

 Fall cohorts in the northcentral Gulf continued for fish 

 7-13 months of age and 20-27 months of age (Table 3). 



Table 4 



Weight-length, girth-length, and total, fork, and standard length regressions for 

 Peprilus burti. All regressions were significant at a = 0.05. Measures are grams and 

 millimeters. 



Maximum size and age 



The maximum size of P. burti is about 200 mm in 

 length. The largest of 32,332 fish we captured off Texas 

 was only 180 mm, though a 198 mm specimen was 

 measured among only 574 fish from the northcentral 

 Gulf east of the Mississippi River (Fig. 7). Off Texas, 

 90% of the fish were less than 122 mm, 99% were 

 less than 142mm, and 99.5% were less than 145mm 

 (Fig. 9). 



The maximum age of P. burti typically was only 

 1-1.5 years in the northwestern Gulf but appeared to 

 be 2-2.5 years in the northcentral Gulf where the 

 largest individuals occur. A t L of 1-1.5 years seems 

 reasonable off Texas, because fish larger than 142- 

 145 mm, which made up less than 0.5-1.0% of the 

 catch, approximate the average size there at age I. A 

 larger t L is appropriate for the northcentral Gulf (Fig. 

 7), because 99-99.5% of the fish west of the Mississippi 

 River were less than 163-167 mm long and 99-99.5% 

 of those to the east were less than 182-184 mm. These 

 sizes approximate the average at age II in the northcen- 

 tral Gulf and the oldest fish collected there was about 

 age II, so a reasonable estimate of t L is 2-2.5 years. 



Total weight-length, girth-length, and 

 length-length relationships 



Regressions of total weight on fork length (Table 4) 

 were significantly different (at a = 0.05) in elevation 

 between sexes (F = 9.19, 1, 1615 df) but not in slope 

 (F = 3.25, 1, 1614 df). Calculated slopes did not sig- 

 nificantly differ from p = 3.0 (males: t = 0.97, 789 df; 

 females: t= 1.60, 825 df) except when all fish were 

 pooled (t = 20.08, 2734 df). Girth- 

 fork length and length-length 

 regressions are in Table 4. 



Equation 



FL 

 range 



logm TW = -4.5517 + 2.9640 log,„ FL 



(males) 

 logm TW = -4.7095 + 3.0477 log 10 FL 



(females) 

 log,„ TW = -4.8621 + 3.1201 logn 

 (males, females, immatures) 



FL 



G 



FL 

 FL 

 TL 

 SL 

 TL 

 FL 

 SL 



10.38 

 -4.31 



8.35 

 -9.35 



3.22 

 -2.88 



5.05 

 -4.46 



+ 0.99 FL 

 + 0.96 G 

 + 0.73 TL 

 + 1.35 FL 

 + 0.69 TL 

 + 1.42 SL 

 + 1.05 SL 

 + 0.95 FL 



791 



827 



2736 



2736 

 2736 

 2662 

 2662 

 2668 

 2668 

 2734 

 2734 



100-163 



94-164 



25-164 



25-164 

 25-164 

 25-164 

 26-164 

 25-164 

 25-164 

 25-164 

 25-164 



0.89 



0.93 



0.99 



0.95 

 0.95 

 0.99 

 0.99 

 0.99 

 0.99 

 0.99 

 0.99 



Discussion 



Spawning periodicity and 

 its regulation 



The broad primary spawning period 

 of September through May we sug- 

 gest for Peprilus burti is realistic. 

 Our data agrees with reports of fish 

 20-40 mm in length from December 

 through June (Gunter 1945, Hoese 

 1965, Miller 1965) and, in part, with 

 a suggested fall and winter spawn- 

 ing (Miller 1965). Moreover, Finu- 

 cane et al. (1979) collected larvae 

 off Texas from September through 

 May. 



