HETTLER: DESCRIPTION OF GULF MENHADEN 



5mm 



FIGURE 6.— Juvenile Brevoortia patronus 33.8 mm (90 d after hatching). 



cleithrum axis on each side. Along the surface, lateral 

 and parallel with the dorsal surface of the foregut, 

 there were usually 6-10, but sometimes up to 20, rec- 

 tangular melanophores on each side. These paired 

 melanophores were positioned anteriad to 2 or 3 

 stellate melanophores covering the dorsal surface of 

 the gas bladder. A series of 10-18 medial, unpaired 

 melanophores occurred between the trunk muscula- 

 ture and the dorsal surface of the gut. This series 

 merged into 1-3 stellate melanophores projecting 

 ventrally over the end of the gut towards the anus. A 

 medial string of nearly continuous, thin mela- 

 nophores traced the junction of the finfold along the 

 ventral surface of the hindgut. Dorsal to the base of 

 the anal fin 2 or more melanophores were always pre- 

 sent in larvae >5 mm. The caudal fin was pigmented 

 by 10 mm, whereas the medial fins, lower jaw tip, 

 snout, and nape acquired pigment by 18 mm (Fig. 

 3C). Pigment was absent on the surface lateral to the 

 ventral portion of the foregut between the distal end 

 of the pectoral fin rays and the pelvic fin. 

 Melanophores were present on specimens >17 mm 

 along the base of the dorsal fin and along the dorsal 

 midline between the dorsal and caudal fins. Paired 

 melanophores were absent between the head and 

 dorsal fin. For pigment descriptions of gulf 

 menhaden larvae and juveniles >19 mm, see 

 Suttkus (1956). 



Other Structures 



By 4.5 mm, the dentaries, maxillaries, branchial 

 arches, cleithra, and hypurals were stained with 

 alcian blue, but the first bones to accept alizarin red S 

 stain, and thus indicate ossification, were the cleithra 

 in 8.5 mm specimens. Flexion of the notochord 



upward to initiate caudal fin development began at 7 

 mm. Ossification of the hypural bones began at 10 

 mm and was completed at 15 mm. Eight maxillary 

 teeth and three dentary teeth on each side were 

 observed on 10 mm larvae. Fourteen teeth on each 

 maxillary and three teeth on each dentary were still 

 visible on 25 mm juveniles. In the oral cavity of 16-24 

 mm larvae, one or two teeth projected downward 

 from each endopterygoid bone and one or two teeth 

 projected upward from the second basibranchial car- 

 tilage. These teeth were absent in fully transformed 

 juveniles. Scales were first visible along the dor- 

 solateral margin of the caudal peduncle and along the 

 midline on each side of the trunk at the beginning of 

 transformation, which occurred at 19 mm. 



COMPARISON AMONG BREVOORTIA 

 AND WITH OTHER CLUPEIDS 



Of the Brevoortia species, eggs and larvae of gulf 

 menhaden were the most difficult to distinguish from 

 yellowfin menhaden. Gulf menhaden had 44-46 

 myomeres, whereas yellowfin menhaden had 45-47 

 (Houde and Swanson 1975). Morphometries may be 

 useful to distinguish 10-25 mm specimens of gulf 

 menhaden from yellowfin menhaden. At equal 

 lengths, gulf menhaden had less body depth, a short- 

 er head length, a longer prepelvic distance, a longer 

 predorsal distance, a shorter snout, and a smaller 

 eye. Yellowfin menhaden >17 mm had paired 

 melanophores between the head and the dorsal fin 

 (Houde and Swanson 1975), whereas gulf menhaden 

 did not. Wild specimens of yellowfin menhaden from 

 southern Florida also had a double row of 

 melanophores along the ventral midline between the 

 pectoral and pelvic fins, but neither laboratory- 



93 



