FISHERY BULLETIN: VOL. 72, NO. 4 



Storey (1938) found eye diameters to be variable 

 for juvenile and adult H. pensacolae. 



Snout Length 



Snout length increased from 1.7 to 7.2% SL 

 for larvae between 4.2 and 22.0 mm (Table 1, 

 Figure 5). It remained constant for longer larvae 

 at about 1.2%, which is within the range of 

 variation for juvenile and adult H. pensacolae 

 (Rivas, 1963). Like eye diameters, snout lengths 

 varied considerably for larvae of a given size; 

 for example, at 12 mm, snout length varied 

 from about 3.1 to 4.8% SL. 



Body Depth 



Body depth at the pectoral symphysis was 

 constant at about 6.5% SL for larvae from 4.2 

 to 9.0 mm. Body depth then increased rapidly 

 from 7.0 to 21.9% SL for specimens between 

 9.0 and 24.0 mm SL. A slow increase continued 

 to occur for larger individuals (Table 1, Figure 4). 



Predorsal Length 



Predorsal lengths, as measured from the snout 

 to the first developing ray in the dorsal fin, 

 were recorded on specimens 7.5 mm and longer, 

 when the rays Ibegan to develop. The dorsal fin 

 moves forward as development proceeds, causing 

 predorsal length to decrease from 68.0% SL to 

 41.7% SL for larvae between 7.5 and 24.0 mm 

 (Table 1, Figure 2). Predorsal lengths averaged 

 41% SL for specimens longer than 24.0 mm. 





16 20 24 28 32 36 40 



STANDARD LENGTH (mm) 



Prepelvic Length 



Prepelvic lengths were measured on larvae that 

 had pelvic fin buds or fins. At 11 to 12 mm, 

 prepelvic lengths averaged about 44% SL, in- 

 creasing to 46% SL for larvae up to 22 mm 

 (Table 1; Figure 3). Prepelvic lengths averaged 

 48% SL for specimens between 24 and 38.7 mm. 

 Pelvic fins moved slightly posterior as larvae 

 transformed to juveniles, causing the observed 

 small increase in prepelvic length. 



Meristics 



Myomeres 



Total numbers of myomeres ranged from 39 

 to 42; most larvae had 40 or 41. Numbers 

 of myomeres and distribution of myomeres in 

 relation to other body parts can be useful for 

 identifying clupeid genera (Ahlstrom, 1968). 

 Total myomeres could be counted accurately on 

 144 of our larvae. Frequencies were as follows: 



Number of myomeres 

 Frequency 



39 



2 



40 

 68 



41 

 67 



42 



7 



Figure 5. — Relation of snout length to standard length for 

 larvae oi Harengula jaguana. 



The mean number of myomeres was 40.56 

 (Si = 0.2861). 



Distribution of myomeres in relation to the 

 dorsal fin and anus was examined for larvae in 

 2-mm size classes (Table 2). Preanal myomeres 

 decreased as larvae grew from about 35 for the 

 smallest larvae to 27 at transformation. Postanal 

 myomeres increased from a mean number of 5.7 

 for the smallest larvae to more than 12 for trans- 

 formed specimens. Shortening of the gut during 

 development accounted for the observed changes 

 in preanal and postanal myomere counts. Mean 

 numbers of predorsal myomeres decreased rapidly 

 from about 25 to 10 as development proceeded, 

 reflecting the anterior movement of the dorsal fin. 

 Considerable variation in predorsal myomere 

 numbers was present for larvae of a given length 

 (Table 2). Postdorsal-preanal myomeres ranged 

 from 5 to 7 for larvae of all sizes, but the mean 

 number tended to decrease as larvae grew from 8 

 to 22 mm. 



Fin Development 



Newly hatched larvae had a fin fold that in- 

 vested much of the body and which persisted in 



1110 



