Figure 12. — Stations at which larvae of Sebastes tevis were taken 

 during 4 yr (1951, 1955, 1968, and 1969) of CalCOFI plankton surveys. 

 Area of total grid is outlined. 



length of parietal spines. Pectoral fin length is 7 to 9% of 

 the body length in larvae up to the beginning of 

 notochord flexion, 9 to 12% during notochord flexion, and 

 has increased to a maximum of 21% following notochord 

 flexion. It is 23% in the transforming specimen (Table 

 17). A morphological feature which helps to distinguish 

 S. cortezi larvae from Type A Gulf larvae is the length of 

 the parietal spines, the spines being relatively shorter in 



Table \7. Measurements (nm) of larvae of Sebastes cortezi- (Specimens between aasned lines 

 are undergoing notocnord flexion.) 



S. cortezi. In larvae between 8.0 and 9.0 mm, when the 

 spines reach their greatest length relative to the head 

 length, those of S. cortezi are 21 to 22% of the head length 

 and those of Type A are 25 to 34%. 



Melanistic pigmentation is more useful than mor- 

 phology in distinguishing S. cortezi larvae from other 

 rockfish larvae. At birth the larvae have the usual pig- 

 ment shield over the gut and a series of melanophores 

 along the ventral midline of the tail (mean of 15 with a 

 range of 10 to 21 melanophores for 15 larvae counted). A 

 large melanophore is located in the position of the future 

 caudal fin and remains there throughout the larval 

 period. The pectoral fins have an unusual pigment pat- 

 tern; there is a melanistic patch in the proximal ventral 

 sector of the fin and the dorsal and distal portions are 

 clear. With further development, the entire proximal 

 region becomes pigmented but the distal clear zone 

 widens. The medial surface of the fin base is covered with 

 large melanophores. The pelvic fins are pigmented in lar- 

 vae 11.8 mm and larger. 



Other pigment develops above the brain and, late in 

 the larval period, on other regions of the head. In larvae 

 about 8.0 mm long a short series of five to six pairs of 

 melanophores develops along the dorsal midline of the 

 tail. With further development this series lengthens, and 

 extends along the entire dorsum in larvae 12.5 mm and 

 longer. The ventral series of melanophores becomes 

 restricted to the caudal peduncle after the anal fin is 

 developed (about 8.0 mm). The 11.8-mm larva has a 

 large patch of melanophores on the lateral surface of the 

 caudal peduncle. In later stages, melanophores extend 

 anteriad along the lateral line from this patch and, in the 

 17.1-mm specimen, the entire trunk above the lateral 

 line is becoming pigmented. 



Distribution.— Eight CalCOFI cruises into the Gulf of 

 California in 1956 and 1957 and a U.N. Food and Agricul- 

 ture Organization (FAO) cruise in March of 1972 provide 

 information on the distribution and abundance of S. cor- 

 tezi larvae. Like the adults (Chen 1975), the larvae occur 

 in the western side of the Gulf and range latitudinally 

 from off Point San Fermin south to about Carmen Is- 

 land (Fig. 14). Most of the larvae were taken just north 

 and just south of the large islands, Tiburon and Angel de 

 la Guarda, in the upper Gulf. Although the results of the 

 various cruises are not strictly comparable because they 

 differed in area covered and in the number of stations oc- 

 cupied, Table 18 gives some indication of the seasonality 

 of spawning. Larvae are present during the cold-water 

 months and appear to have a maximum abundance in 

 March. 



Table 18. Mean length (nin) with total standardized number of larvae of Sebastes 

 cortezi and S. Type A in p1anl(ton collections from the Gulf of California. 



•Transfonning specimen. 



24 



