FISHERY BULLETIN: VOL. 72. NO. 2 



and were obscured or lost in larvae of about 

 26 days (10.9 mm SL). 



DORSUM. — Dorsum pigmentation of the post 

 yolk sac larvae of four days of age (2.6 mm SL) 

 consisted of a single line of 9 to 13 large, stellate 

 melanophores extending posteriad from the base 

 of the hindbrain to the 17th to 19th myomere 

 along the dorsal edge of the body (Figure 2C). 

 At ten days (4.0 mm SL), numerous small 

 melanophores had formed ventro-laterally, inter- 

 spersed along the prominent line of melanophores 

 of the dorsal edge. The appearance of these 

 lateral melanophores coincided with the appear- 

 ance of dorsal and anal fin anlagen (which were 

 visible as opaque thickenings in the fin fold). 



By day 12 (Figure 2D) (4.5 mm SL) the dorsal 

 melanophores had become smaller and more 

 numerous, bordering each side of the ventral 

 margin of the dorsal fin anlage. The formerly 

 conspicuous single row of large melanophores 

 on the edge of the dorsum was now lost, having 

 been replaced by these smaller dorsal melano- 

 phores in a double row along the base of the fin 

 anlage and continuing in a single row posteriorly. 



Larvae of 15 to 16 days of age (5.2-6.2 mm 

 SL) showed increased lateral spreading of pigmen- 

 tation. By 18 days (7.4 mm SL) (Figure 3A), 

 melanophores had formed along the more pos- 

 terior two-thirds epaxial myoseptal lines, which 

 became more pronounced in 20-day-old larvae 

 (8.3 mm SL). This epaxial myoseptal pigmenta- 

 tion pattern was gradually obscured by the 

 increasing density of pigmentation over the entire 

 area of the dorsum beginning in 22-day-old larvae 

 (9.5 mm SL). 



The caudal peduncle remained sparsely pig- 

 mented both dorsally and ventrally throughout 

 development. (The pigment along the base of the 

 caudal fin is described in the section on fin 

 pigmentation.) 



VENTRUM. — The pigmentation changes of the 

 ventrum from the four-day-old larvae followed a 

 similar pattern to that of the dorsum with a few 

 exceptions. The larvae of four to eight days of 

 age exhibited a single line of 12 to 26 small 

 melanophores along the ventral edge of the body 

 from the anus to the 23rd or 24th myomere. These 

 ventral melanophores were smaller and extended 

 more posteriad than those aligned along the 

 dorsal edge of the body until fin formation was 

 well initiated. In addition, two to four minute 



punctate melanophores appeared on the ventral 

 tip of the notochord (which subsequently migrated 

 ventrally to become situated along the proximal 

 edges of the caudal actinotrichia discussed in the 

 section on fin pigmentation). 



With the first appearance of the anal fin 

 anlage in ten-day-old specimens, faint melano- 

 phores formed dorsolaterally over the ventrum, 

 followed by the appearance of a double line of 

 melanophores along the base of the anal fin 

 anlage in 12-day-old larvae (4.5 mm SL) from 

 the previously single line as it occurred along the 

 base of the dorsal anlage. From day 14 to 16 

 (5.2-6.2 mm SL), melanophores formed a con- 

 spicuous pattern along the hypaxial myoseptal 

 lines, with others scattered in the surrounding 

 region (Figure 3A, B). These latter were most 

 concentrated over the ventral one-third of the 

 hypomeres. The hypaxial myoseptal pigment 

 pattern remained visible in the largest larvae 

 (18.0 mm) in contrast to that on the dorsum 

 and remained as a major distinguishing char- 

 acteristic. 



"LATERAL LINE STREAK".— The "lateral 

 line streak" refers to the dashed line of pigmen- 

 tation along the lateral midline of the body as 

 described for several other carangid larvae (see 

 Ahlstrom and Ball, 1954; and Kramer, 1960). 

 It appeared in the six-day (Figure 2C) omaka 

 larvae (3.0 mm SL) with two or three elongate 

 melanophores arising near the vertical of the 

 anterior portion of the hindgut, with as many as 

 13 melanophores having formed in eight-day-old 

 (3.5 mm SL) larvae. Indeed, body pigmentation 

 of the larvae at this age was characterized by 

 three lines: along the dorsal and ventral edges 

 of the body, and the lateral line streak. 



Although it was largely obscured by the over- 

 growth of tissue and heavier lateral pigmentation, 

 the streak was still noticeable in the 36-day-old 

 larvae (16.6 mm SL). It provided a sharp line 

 of demarcation between the heavily pigmented 

 dorsum and the more sparsely pigmented ven- 

 trum in the older larvae (Figure 3B). 



Fin Pigmentation 



CAUDAL. — Prior to notochord flexion, a few 

 small melanophores were present along the distal 

 margin of the early hypural plate (Figure 2D). 

 In addition, a line of minute melanophores had 

 formed along the ventral margin of the caudal 



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