FISHERY BULLETIN: VOL. 80, NO. 3 



ichthyoplankton from the shallow coastal waters 

 of the Southern California Bight. 



SUMMARY 



1) The G. lineatus egg is pelagic, transparent, 

 and spherical with an unsculptured chorion, un- 

 segmented yolk and a single clear to yellowish oil 

 droplet. The live egg averages 0.85 mm in diame- 

 ter and the oil droplet 0.23 mm. Hatching occurs 

 about 52 h after spawning. 



2) Yolk-sac larvae hatch at about 1.8 mm in an 

 undifferentiated state with unpigmented eyes, 

 straight tubular gut, large yolk sac, and posteri- 

 or oil droplet. Pectoral buds develop during the 

 second day after hatching, the mouth opens and 

 gut begins differentiating on the third, eye pig- 

 mentation is complete on the fifth, and yolk 

 exhaustion and swim bladder inflation occurs on 

 the sixth. 



3) Yolk-sac larvae initially are pigmented pri- 

 marily on the dorsum. During the yolk-sac peri- 

 od melanophores migrate toward the ventral 

 midline. 



4) Pigmentation is largely restricted to the 

 ventrum and dorsal surface of the gut through 

 much of the larval stage. A nape melanophore 

 and the large internal melanophore on the lower 

 anterior midline of the visceral mass are char- 

 acteristic. A barred pattern develops during the 

 transition to the juvenile stage. 



5) The order of ossification (first uptake of ali- 

 zarin stain) is: cleithra (2.6 mm); splanchnocra- 

 nium, hyoid apparatus, opercular apparatus, 

 branchial apparatus, skull (4 mm); caudal fin 

 rays (4.8 mm); vertebrae (5.6 mm); second dorsal 

 and anal fin rays and hypural complex (6 mm); 

 first dorsal and pelvic fin rays (7.2 mm); and pec- 

 toral fin rays (7.8 mm). Each fin ray begins to 

 ossify before its supporting structure. 



6) The principal characters useful for separat- 

 ing G. lineatus from similar larvae are the nape 

 melanophore, the anterior visceral mass melano- 

 phore when in its ventral position, the larger 

 midventral melanophores at myomeres 9-10 and 

 16-18, and fin ray and myomere counts. 



7) Genyonemus lineatus spawns mainly from 

 October through April, with peak spawning in 

 late winter. 



8) Larvae are located principally within 4 km 

 from shore. As they develop they tend to move 



cooling system. Marine Ecological Consultants of Southern 

 California, 533 Stevens Ave., Solana Beach, CA 92075, 32 p. 



shoreward and into the lower 1 m of the water 

 column. 



ACKNOWLEDGMENTS 



This study was partially supported by a con- 

 tract to Marine Ecological Consultants of South- 

 ern California from the Marine Review Commit- 

 tee of the California Coastal Commission for the 

 study of ichthyoplankton at the San Onofre Nu- 

 clear Generating Station. Statements and con- 

 clusions in this paper do not imply approval or 

 endorsement by the Marine Review Commit- 

 tee. 



I am grateful to Jeffrey Leis, Geoffrey Moser, 

 and H. J. Walker who reviewed an earlier draft 

 of this manuscript and offered innumerable val- 

 uable comments. I also wish to thank the many 

 technicians involved in collection and processing 

 of samples, and Judy Sabins for typing the many 

 versions of this manuscript. 



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416 



