WATSON: DEVELOPMENT OF EGGS AND LARVAE OF WHITE CROAKER 



Table 5.— Selected characters of larvae which resemble Genyonemus lineatus. 



Species 



'52 specimens. 2.6-8.1 mm SL. 

 2 94 specimens. 2.6-9.7 mm SL 

 3 19 specimens. 2.2-4 3 mm SL. 



4 50 specimens, 3.6-9 8 mm SL. 



^aken from Kramer 1960, table 5. Larvae 4.00-9.99 mm SL 



6 20 specimens, 2.2-5 5 mm SL. 



(Table 5). Anisotremus davidsonii commonly has 

 a uniform row of one midventral, postanal trunk 

 melanophore per myomere after the first post- 

 anal myomere, and nearly always has a large 

 melanophore anteriorly on the ventral midline of 

 the gut. As many as four smaller melanophores 

 may also be arrayed along the midline of the gut. 

 Genyonemus lineatus, in contrast, rarely dis- 

 plays uniformity in the midventral, postanal 

 melanophore series (those at myomeres 9-10 and 

 16-18 typically are distinctly larger), and the 

 ventral gut pigmentation usually is not on the 

 midline. Genyonemus lineatus is deeper bodied 

 and its hindgut turns down at a much steeper 

 angle than that of A. davidsonii. 



Seriphus politus lacks the banded pattern of 

 young G. lineatus larvae and usually displays an 

 approximately uniform series of small, postanal 

 midventral melanophores (Moser and Butler 

 footnote 5). Shortly before anal anlage develop- 

 ment two melanophores of the midventral series 

 typically enlarge in S. politus; these lie at myo- 

 meres 11-13 and 19-21 versus 9-10 and 16-18 for 

 G. lineatus. During anal fin development the 

 anterior of these migrates internally in G. linea- 

 tus but remains external in S. politus. Specimens 

 smaller than 8 mm are often distinguishable by 

 the presence and size of the melanophore above 

 the hindgut (Table 5). The melanophore on the 

 anterior visceral mass also distinguishes these 

 two after it has assumed its ventral position in G. 

 lineatus. Seriphus politus larvae are somewhat 

 more slender than G. lineatus. Anal fin ray 

 counts separate older specimens. 



Roncador stearnsii larvae closely resemble G. 

 lineatus (Moser and Butler footnote 5). Before 

 acquisition of fin rays R. stearnsii may often be 

 distinguished by having rather heavy anterior 

 gut pigmentation (usually light in G. lineatus), 



by the large melanophore above the hindgut, and 

 by one to three pairs of internal melanophores 

 along either side of the midline of the head be- 

 hind the eye at the level of the floor of the otic 

 capsule plus one or two medially under the fore- 

 brain (these often give the appearance of a stripe 

 through the eye, lacking in G. lineatus). Dorsal 

 and anal fin ray counts separate older specimens. 



DISTRIBUTION 



Genyonemus lineatus off southern California 

 spawns principally from October through April 

 (Skogsberg 1939; Goldberg 1976). This is consis- 

 tent with our study off San Onofre: larvae were 

 taken from January (initiation of our study) 

 through early June 1978, and early October 1978 

 through late June 1979, with abundance peaks in 

 March 1978 and February 1979 (Walker et al. 

 footnote 2). Few larvae were taken in June or 

 October. 



The smallest larval G. lineatus were most 

 abundant in the epibenthos (lower 0.5 m) shore- 

 ward of about 3.9 km (21m isobath) and in the 

 water column above the epibenthos between 2 

 and 3.9 km from shore (13 and 31 m isobaths). 

 During development, they move shoreward and 

 tend to become more strongly epibenthic. This is 

 evidenced by the low abundance of larvae be- 

 tween ca. 3.8 and 6.4 mm in the water column 

 and offshore of 3.9 km. Larvae larger than 6.4 

 mm are virtually absent above the epibenthos. 

 The abundance peak for G. lineatus\sirva.e larger 

 than ca. 3.8 mm is between 1 and 2 km from shore 

 (9 to 12 m isobaths) 6 . Brewer et al. (in press) 

 noted a similar distribution in their study of the 



6 Barnett, A. M.. A. E. Jahn. P. D. Sertic, and W. Watson. 

 1980. Long term spatial patterns of ichthyoplankton off San 

 Onofre and their relationship to the position of the SONGS 



415 



