FISHERY BULLETIN: VOL. 72, NO. 2 

 Table 10. — Measurements (mm) of larvae and juveniles of Oligoplites saurus. 

 (Specimens between dashed lines are undergoing notochord flexion; W - wild, L - laboratory reared.) 



stages. Hypaxial muscles enclose the gut at 4 mm, 

 and the abdominal cavity is completely covered at 

 7.2 mm. 



As in most carangid larvae, the head is long and 

 deep. Relative head length ranges from 23 to 36% 

 of standard length during the larval and juvenile 

 periods. Depth of head ranges from 82 to 100% of 

 the head length. The dorsal profile of the snout is 

 convex except for a slight indentation at the an- 

 terior margin of the forebrain. The eyes are round 

 and large; eye index ranges from 20 to 44% during 

 the larval and early juvenile periods and is high- 

 est in larvae 2 to 3 mm long. Pigmentation de- 

 velops on the second day of hatching. A finely ser- 

 rated orbital crest is present in larvae from 4 mm 

 long and is gradually resorbed following 

 metamorphosis. Preopercular spines are present 

 but only the marginal ones are well developed. 

 One to three denticles occur on the dorsal side of 

 the longest marginal spine. 



The scales and lateral line are not yet developed 

 in 25-mm juveniles, the oldest of the laboratory- 

 reared specimens. 



Pigmentation 



Larval pigmentation is well developed and 

 progressively increases during the larval and 

 juvenile stages. Pigment cells are more abundant 



in laboratory-reared specimens than in the wild 

 ones. A conspicuous U-shaped, unpigmented area 

 at the caudal peduncle persists from 7.2 mm up to 

 the early juveniles 20 mm long (Figure 8H-J). 

 Throughout the larval and juvenile stages xanth- 

 ophores are present on the sides of the body, but 

 they readily fade on preservation. Melanophores 

 form at the base of the dorsal finfold in the early 

 larvae but disappear when the fin rays are dif- 

 ferentiated. The conspicuous anal pigment spot in 

 the embryo and newly hatched larvae disappear at 

 the third day of hatching. In the early juveniles, 

 pigmentation develops on the membrane of the 

 dorsal and anal fin spines. 



Fin Development 



The dorsal, anal, and caudal finfolds are present 

 at hatching, and the sequence of ossification is as 

 follows: 1) dorsal, anal, and caudal; 2) pectoral and 

 pelvic (Table 11). 



The pectoral finfold is formed a day after hatch- 

 ing. As in other larvae described here, the pectoral 

 fin rays begin to ossify dorsally and the rest are 

 added ventrally. The full complement of 15 to 17 

 rays is completed at 10 mm. 



The pelvic fin buds appear 13 days after hatch- 

 ing at 6 mm and the rays soon become differen- 

 tiated. The full complement of 1 spine and 5 soft 

 rays is present at 10 mm. 



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