MOSER: DEVELOPMENT OF ROCKFISH 





L 





Figure 3. — Pelagic juveniles of Sebastes macdonaldi. A. A 15.4-mm transforming specimen (SIO 65-201, mid- 

 water trawl) which is just beginning to develop its juvenile melanophore pattern. Note that it is further ad- 

 vanced than the 15.9-specimen in Figure 2. B. A 29.2-mm specimen dipnetted on surface at night (SIO 69-232). 



the body length in the stages before notochord 

 flexion, 13% during flexion, and 19% in the 

 stages following flexion. The fin elongates mark- 

 edly in pelagic juveniles in which its average 

 length is 31% of the body length (Figures 3B, 

 4A) . This sequence of gradual elongation of the 

 pectoral fins throughout the larval and early 

 juvenile period contrasts with that observed in 

 S. paucispinis (Moser, 1967). In that species, 

 the maximum length of the pectoral fins, 40% 

 of the body length, is achieved in 13-mm larvae 

 and, thereafter, the pectoral fin length decreases 



relative to body length ; pectoral fin length is 

 25% of the body length in newly transformed 

 juveniles of S. paucispinis. In both species, the 

 heavily pigmented pectoral fins are the most 

 striking features of larvae and early juveniles. 

 The pelvic-fin buds appear early, in larvae as 

 small as 6.3 mm, and become covered with mela- 

 nophores. The rays begin to diff"erentiate in 

 7-mm larvae. Ossification of the spines is visible 

 initially in a 7.7-mm specimen in the stained 

 series (Table 2). Ossification of the rays pro- 

 ceeds sequentially posteriad from the spines; the 



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