FISHERY BULLETIN: VOL. 80. NO. 3 



bladder; as many as two lie on the middorsal 

 surface on the gut just behind the swim bladder; 

 one small melanophore usually lies on the dorsal 

 hindgut just where it turns downward at myo- 

 mere 5 or 6; a larger melanophore lies adjacent 

 to the hindgut just anterior to the anus, one 

 rather large melanophore may lie on the anterior 

 midline of the visceral mass just below the level 

 of mideye; none to several small melanophores 

 are scattered ventrally and ventrolateral^ over 

 the anterior gut. 



Gut pigment generally decreases during lar- 

 val development. The melanophore behind the 

 pectoral base rarely persists beyond 5.2 mm. 

 Swim bladder pigment increases but remains 

 restricted to its dorsal surface through the larval 

 period. All other dorsal gut pigment except the 

 melanophore on the hindgut is lost by ca. 3 mm 

 and usually does not reappear until ca. 11.2 mm, 

 near the end of the larval stage. The dorsal me- 

 lanophore on the hindgut is present more often 

 than not (present in 63% of the larvae examined) 

 and is nearly always quite small in specimens 

 smaller than ca. 8 mm. In larger specimens it is 

 nearly always present (in 95% of the larvae exam- 

 ined) and increases in size (occasionally others 

 are added as well) to nearly cover the dorsal sur- 

 face on the hindgut by ca. 11.2 mm (Fig. 5). In 

 older specimens melanophores begin to fill in be- 

 tween the swim bladder and hindgut, so that in 

 early juveniles the dorsal gut cavity is often 

 entirely pigmented. 



The melanophore just anterior to the anus 

 usually persists through ca. 6 mm but is rarely 

 present in larger specimens. Other ventral gut 

 pigment is quite variable early in the larval per- 

 iod, ranging from one to several melanophores 

 typically on the anterior half of the gut. The ven- 

 tral midline of the gut often remains unpig- 

 mented throughout larval life. Only a single 

 melanophore just anterior to the cleithral sym- 

 physis commonly remains after 5 mm (present in 

 64% of the larvae examined). During the transi- 

 tional period one or two additional melanophores 

 develop to form a series along the midline of the 

 isthmus. After completion of the pelvic fin (ca. 9 

 mm) a single melanophore may appear between 

 the pelvic bases. During transition a ventral 

 midline series of two or three melanophores may 

 arise behind the pelvic fin bases. 



The large internal melanophore located anter- 

 iorly on the upper visceral mass migrates ven- 

 trally as larval development proceeds: when 

 present it is nearly always on the upper visceral 



mass in larvae smaller than ca. 4 mm, is most fre- 

 quently located halfway down between 4 and 6 

 mm (Fig. 4c), and is nearly always present at the 

 lower anterior margin of the visceral mass in 

 specimens larger than ca. 6 mm (Fig. 4d). 



Fin Development 



At the beginning of the larval period G. linea- 

 tus larvae have only a broad medial finfold and 

 pectoral fin without rays. Subsequent fin devel- 

 opment follows a typical sciaenid sequence (e.g., 

 Powles 1980; Pearson 1929). 



The caudal fin is first to develop. The caudal 

 anlage appears at ca. 3.8 mm and the central four 

 to six principal rays begin to ossify at ca. 4.8 mm. 

 Notochord flexion begins at ca. 5.4 mm and is 

 complete at ca. 6.4 mm. The full complement of 

 9+8 principal caudal rays is ossified by the end of 

 flexion. Further development includes the addi- 

 tion of secondary caudal rays ( 15 to 17 total by the 

 early juvenile stage), branching of the central 

 principal rays and lengthening of the fin. The 

 central rays are longest throughout larval devel- 

 opment. 



Anal and dorsal fin anlagen appear nearly 

 simultaneously at ca. 5 mm. The anal fin anlage 

 is short, usually extending between myomeres 13 

 and 18. Differentiation begins with the most 

 anterior anal soft ray bases just after the anlage 

 first appears, and proceeds posteriorly. The 

 sequence of anal fin ray differentiation follows 

 that of the ray bases, beginning with the first soft 

 ray at ca. 6 mm and proceeding posteriorly. All 

 anal soft rays are discernible by ca. 6.7 mm, at 

 which time the second anal spine begins to ossify. 

 The first anal spine completes the anal fin ray 

 complement at ca. 7.2 mm. Subsequent larval 

 development consists of lengthening of the rays 

 and ossification of the pterygiophores. 



The dorsal anlage initially lies between the 

 tenth and fifteenth myomeres and lengthens to 

 myomeres 3-21 by ca. 6 mm. As in anal fin de- 

 velopment, the anterior soft ray bases differen- 

 tiate first, beginning at ca. 5.4 mm, and the soft 

 rays ossify from the first ray posteriorly begin- 

 ning at ca. 6 mm. The posterior 8 to 10 bases are 

 undifferentiated as the first soft rays begin ossi- 

 fying. Dorsal spine bases begin differentiating 

 anteriorly at ca. 6.4 mm and the anterior spines 

 appear at ca. 7.2 mm, about the time of acquisi- 

 tion of the full complement of dorsal soft rays. 

 The dorsal spines ossify posteriorly, reaching the 

 adult complement of 12 to 15 by 8.0-8.5 mm. The 



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