Hildebrand (1963) reported eye diameters ranging 

 from 6.1 to 7.5% SL for specimens 91 mm and 

 longer. 



Snout Length 



Snout length increased gradually throughout 

 development. It averaged 2% SL at hatching and 

 increased to 7 to 8% SL in our juveniles (Table 4). 

 Snout lengths of large juvenile and adult yellowfin 

 menhaden range from 6.8 to 8.0% SL (Hildebrand 

 1963). 



Body Depth 



Body depth, measured at the pectoral 

 symphysis, averaged 8 to 9% SL from hatching 

 until larvae were 12.0 mm (Table 4). A rapid 

 increase in body depth then occurred; it was 23% 

 SL at 18.0 mm and apparently was still increasing 

 in juvenile specimens 22.7 mm and longer. Our 

 36.2-mm specimen had a body depth of 33% SL. 

 Hildebrand (1963) did not measure body depth by 

 the same method that we used, but he noted that 

 yellowfin menhaden juveniles are deep bodied, 

 more so than adults of this species. 



Predorsal Length 



Predorsal lengths were measured on larvae that 

 had dorsal fin rays developing. No dorsal fin 

 development was observed on any specimens less 

 than 7.3 mm. Predorsal length decreased gradually 

 from 67 to 62% SL for larvae from 7.3 to 14.0 mm 

 and then decreased more rapidly for larger 

 specimens (Table 4). It was 52% SL for our 22.7- 

 mm specimen and ranged from 47 to 49% SL for 

 larger individuals. The decrease in predorsal 

 length from 67 to 62% for 7.3- to 14.0-mm larvae 

 may be partly due to measuring predorsal length 

 on specimens with incompletely developed dorsal 

 fins. The marked decrease in predorsal length on 

 larger larvae resulted from forward movement of 

 the dorsal fin as larvae began to transform to the 

 juvenile stage. 



Prepelvic Length 



Prepelvic lengths were measured on larvae that 

 had pelvic fin buds or fins. From 11.1 to 16.0 mm, 

 prepelvic lengths ranged from 47 to 49% SL (Table 

 4). In larger specimens, prepelvic lengths 



increased to 51% SL at 18.0 mm and to about 52% 

 SL for 22.7- to 33.3-mm individuals. Our 36.2-mm 

 specimen had a prepelvic length of 55% SL. Pelvic 

 fins moved posteriorly during growth of yellowfin 

 menhaden larvae, causing the observed increase in 

 prepelvic length. 



Meristics 



Myomeres 



The number of myomeres in fishes corresponds 

 approximately to the number of vertebrae. Dahl- 

 berg (1970) reported 43 to 46 vertebrae (mean = 

 45) for juvenile and adult B. smithi. Myomeres can 

 be counted on larvae before development of ver- 

 tebrae and are a valuable meristic character. Total 

 numbers of myomeres in our specimens ranged 

 from 45 to 47 on the 63 individuals for which ac- 

 curate counts were obtained. There was no 

 correlation between the number of myomeres and 

 standard length, indicating that the full 

 complement was present at hatching. The 

 frequencies of occurrence were as follows: 



Number of myomeres 

 Frequency 



^ ^6 1+7 

 26 32 5 



The mean number of myomeres was 45.67 (Sj- = 

 0.1109). 



The distribution of myomeres in relation to 

 other body parts can be useful for identifying 

 clupeid larvae (Ahlstrom 1968). We examined the 

 distribution of myomeres for yellowfin menhaden 

 larvae relative to the dorsal fin and anus (Table 3). 

 Preanus myomeres decreased from a mean 

 number of 37.6 in newly hatched larvae to 28.5 in 

 juveniles that were 22.7 mm and longer. Postanus 

 myomeres increased accordingly, from 8.0 in 

 newly hatched larvae to 17.0 for juveniles. Short- 

 ening of the gut during development caused the 

 change in distribution of preanus and postanus 

 myomeres. Predorsal myomeres decreased in 

 numbers as larvae developed, because the dorsal 

 fin moved forward. Larvae of 6.1 to 8.0 mm had a 

 mean number of 28.0 predorsal myomeres, but 

 juveniles had only 15.8. Numbers of predorsal 

 myomeres were variable for specimens within any 

 given size class (Table 3). The number of postdor- 

 sal-preanus myomeres decreased as larvae grew. 

 Larvae 6.1 to 8.0 mm had a mean number of 5.3 

 postdorsal-preanus myomeres, but advanced lar- 

 vae and juveniles always had 4 or fewer (usually 2 



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