MOSER: DEVELOPMENT AND DISTRIBUTION OF SEBASTOLOBUS 



southern California, adults of even the 

 shallower-living species, S. alascanus, are gener- 

 ally restricted to waters deeper than 150 fathoms. 



Curtailment of spawning or mortality of fer- 

 tilized eggs off southern California is evident 

 from the distribution of Sebasfolobus larvae in 

 the CalCOFI sampling area (Figures 11, 12). In 

 1966, there were no occurrences south of line 97, 

 which runs seaward from the Mexican border, 

 and in 1969 Sebastolobus occurred on only two 

 stations below this line. It is apparent that the 

 CalCOFI sampling pattern did not encompass the 

 offshore limits of larval distribution and that lar- 

 vae occur well seaward of the 200 to 250 mile 

 coastal zone sampled during these years. 



The seasonal abundance of Sebastolobus larvae 

 for 1966 and 1969 is shown in Table 7. In 1966 

 larvae were taken from April to October in cen- 

 tral and southern California. Numbers of larvae 

 and occurrences were highest in April and di- 

 minished in subsequent months. No larvae were 



Figure 11. — Stations at which larvae of Sebastolobus were col- 

 lected during CalCOFI survey of 1966. Dots indicate stations 

 where numbers of Sebastolobus larvae exceeded mean number 

 (7.2) for all positive stations. Area of frequent occupancy is 

 outlined (see Ahlstrom, 1961, for complete grid). 



Figure 12. — Stations at which larvae of Sebastolobus were col- 

 lected during CalCOFI survey of 1969. Symbols as in Figure 11. 



taken south of southern California in 1966. In 

 1969, larvae appeared earlier in the year, from 

 January to December off central California, from 

 January to October off southern California, and 

 from June to September off northern Baja 

 California. Again, numbers of larvae and occur- 

 rences peaked in April off central and southern 

 California. Data for the two species are lumped 

 together in Table 7. Of the larvae identifiable to 

 species, those over 10 mm, 6% were S. alascanus 

 in 1966 and 12% wereS. alascanus in 1969. Thus, 

 the data in Table 7 pertain largely to S. altivelis. 



Although Sebastolobus larvae are taken in 

 plankton tows over a large proportion of the year, 

 the spawning season is relatively short. Table 8 

 shows the seasonal change in the size of Sebas- 

 tolobus larvae. The mean size increases steadily 

 throughout the year and small, recently spawned 

 larvae, less than 5 mm, do not occur after June in 

 1966 and May in 1969. This indicates a spawning 

 season of 4 or 5 mo. 



Information on the growth rate of the pelagic 

 juveniles of both species of Sebastolobus was ob- 

 tained by examining mid-water trawl samples 



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