182 



Fishery Bulletin 93(1). 1995 



curred in the following sequence: pel- 

 vic and dorsal spines, caudal, dorsal and 

 anal soft rays, pectoral rays (Table 1). 

 The spinous pelvic and dorsal fin for- 

 mation occurred simultaneously at 4. 10 

 mm. Dorsal and anal fin analage were 

 first visible at 4.51 mm and ray bases 

 were fully formed by 5.35 mm. Caudal 

 flexion and caudal ray formation oc- 

 curred in larvae between 4.40 and 4.75 

 mm and was followed by development 

 of the soft rays of the dorsal and anal 

 fins (Fig. 3A); additionally, the spines 

 of the dorsal and pelvic fins were 

 strongly serrated. By 6.23 mm SL, all 

 juveniles had the full adult complement 

 of fin spines and rays (Fig. 3B); however, 

 serrated spines, characteristic of larvae, 

 were still present on juveniles 14.66 mm. 



Growth and shrinkage 



Laboratory-reared yellowtail snapper 

 showed large variation in size among 

 larvae of the same age (Table 1), and 

 key developmental events were tightly 

 linked to larval size more than to age. 

 Growth rates prior to flexion averaged 

 0.31 mm/day and decreased to only 0.18 

 mm/day during the process of transfor- 

 mation to juveniles (4.83-7.00 mm SL, 

 ages 14-28 days). During the last month 

 and a half of recorded development, ju- 

 venile growth averaged 0.25 mm/day. 



Mean daily lengths of postpreser- 

 vation larvae are listed on Table 1. 

 Shrinkage after preservation was great- 

 est in larvae prior to any fin develop- 

 ment (<4.00 mm), averaging 10.36% 

 through the first 13 days. Larvae with 

 partial fin development (4.83-5.72 mm 

 SL) shrank an average of 9.32%. Once 

 larvae attained complete development 

 of the dorsal and pelvic fins (>5.00 mm); 

 shrinkage was reduced to an average 

 of 7.24% throughout the remaining ju- 

 venile stages examined. 



Figure 3 



Late developmental stages and mean lengths of yellowtail snapper. Dark 

 arrows indicate location of yellow chromatophores. (A) 4.64-4.80 mm SL, 

 days 15-16; (B) 6.23-6.73 mm SL, days 18-28; (C) 14.66 mm SL, day 31, 

 drawn from preserved specimen; (D) 16.05 mm SL, day 62, from preserved 

 specimen. 



Discussion 



Ocyurus chrysurus have similar larval characteris- 

 tics to the previously described snappers Lutjanus 

 campechanus (Collins et al., 1980), L. griseus 

 (Richards and Saksena, 1980), and Rhomboplites 



aurorubens (Laroche, 1977). Preflexion larvae of each 

 of the four species have a series of chromatophores 

 along the ventral midline and have pigment cover- 

 ing the dorsum of the gut and gas bladder. All have 



