FISHERY BULLETIN: VOL. 82, NO. 1 



About 15-20 myomeres were visible in the caudal 

 region. The yolk was faintly segmented into irregular 

 globules. E ggs hatched in 40-42 h at a water tempera- 

 ture of 19°-20°C. 



Atlantic menhaden eggs spawned in the laboratory 

 were larger than gulf menhaden eggs in total 

 diameter (1.54- 1.64 mm) but similar in yolk diameter 

 (0.82-0.95 mm) and oil droplet diameter (0.20- 

 0.23). 



Larvae 



Growth 



Gulf menhaden larvae were 2.6-3.0 mm SL 

 immediately after hatching (Fig. IB), but within 6 h 

 had a mean length of 3.3 mm. The yolk and oil droplet 

 were absorbed, the eyes were pigmented, and the 

 mouth was functional at a length of 4.5 mm, 4 d after 

 hatching. The growth rate of larvae at 20° ± 2°C 

 averaged 0.30 ± 0.03 mm/d through 90 d of rearing 

 (Fig. 2). Yellowfin menhaden reared for 32 d at 20°C 

 grew 0.36 mm/d (Hettler 1970). Yellowfin menhaden 

 reared at 26°C grew 0.45 mm/d until the 20th day 

 (Houde and Swanson 1975). 



Body Proportions 



For 123 gulf menhaden, 3.1-34.9 mm, body depth, 

 head length, prepelvic length, dorsal fin base length, 

 anal fin base length, snout length, and eye diameter 

 all increased relative to standard length as larvae 

 grew, while preanus length and predorsal length de- 



36 r 



32 



28 



e 



I 

 | 20 



LLI 



_l 



D 16 

 DC 

 < 

 D 



I 12 



co 

 8 



./: 



10 20 30 40 50 60 70 80 90 

 DAYS AFTER HATCHING 



FlOlRE 2. — Growth of laboratory-reared larvae of Hrcvaartki pa- 

 t ran us. Lines connect means of each age group. 



creased (Table 2). The decrease in predorsal length 

 resulted from the forward movement of the dorsal fin, 

 and the decrease in preanus length reflected the 

 transformation from an elongate clupeiform larva 

 shape to the laterally flattened fusiform shape of the 

 juvenile. Transformation from the larval to the 

 juvenile form in gulf menhaden began at about 19 

 mm (Fig. 3C) and was completed at about 25 mm. 

 Atlantic menhaden larvae completed transformation 

 at about 27 mm. 



TABLE 2. — Proportions of head and body parts of gulf menhaden, Brevoortia patronus, expressed as a percent of stan- 

 dard length. Characters were not developed at lengths marked with a dash. 



88 



