Tolan and Newstead: Larval and |uvenile development of Brevoortia gunten 



725 



caudal peduncle, and eye diameter ratios all similarly 

 increased in relation to standard length as larvae grew, 

 whereas snout-to-anal length decreased (Table 2). Scale 

 initiation in gulf menhaden was not seen until 19 mm, 

 and ventral scutes did not begin forming until around 

 18 mm. The full complement of scutes (28-32 scutes; 

 McEachran and Fechhelm, 1998) was seen by around 

 25 mm. No enlarged median dorsal scales were noted 

 from the gulf menhaden individuals examined. 



With little overlap in the 15-20 mm size range (see 

 Fig. 1) and a limited number of juvenile-size finescale 

 menhaden (SL>20 mm), it was not possible to effectively 

 separate finescale and gulf menhaden morphometrically 

 on the basis of BD:SL, PAL:SL, CP:SL, and EYE:SL 

 ratios (Fig 3). By 25 mm, proportional body measure- 

 ments had become nearly constant for gulf menhaden 

 whereas body measurements were still changing for 

 finescale menhaden even though they appeared to be 

 fully transformed. For a fish of given size, finescale 

 menhaden typically had a greater body depth, a shorter 

 preanal length, and a greater caudal peduncle length 

 than gulf menhaden. 



Meristic features 



No recently hatched or preflexion finescale menhaden 

 were examined and all postflexion individuals followed 

 the fin development sequence identified for other clupe- 

 ids (Houde et al., 1974: Hettler, 1984; Ditty et al., 1994). 

 The caudal and dorsal fins are first to develop, followed 

 by the pelvic fins, whereas the pectoral fins are the 

 last to fully develop even though the pectorals are the 

 first fins to form as nonrayed buds. Only vertebrae and 

 dorsal-fin ray counts were useful in separating finescale 

 and gulf menhaden, because most other meristics over- 

 lapped (Table 3). Finescale menhaden had fewer total 

 vertebrae ( = 43 vs. 46) and fewer dorsal-fin rays (median 



value = 18 vs. 21) than gulf menhaden. Postdorsal and 

 preanal vertebrae also showed a high degree of overlap 

 between the two species (Table 3). The forward move- 

 ment of the anal fin in relation to the dorsal fin was 

 most evident in fully transformed gulf menhaden, and 

 the number of postdorsal-preanal vertebrae decreased 

 from 4 to -3. The relative placement of the anal fin also 



