those trawls containing one or more specimens of 

 S. diploproa were considered, a total of 96 trawls. 



Results 



Surface dip net collections consisted of 873 pre- 

 juveniles, the largest of which was 58.7 mm stan- 

 dard length (SL). A total of 2,418 benthicjuveniles 

 were taken in the trawl collections, with the fol- 

 lowing size breakdown: <30mm, 2; 30-39 mm, 84; 

 40-49 mm, 892; and 50-59 mm, 1,440. Few pre- 

 juveniles larger than 50 mm SL were captured in 

 surface collections (Figure 1); thus they appear to 

 settle out at a size under 50 mm. At this size 

 prejuveniles are about 1 yr old according to 

 laboratory growth measurements (unpublished 

 data) and the growth curve determined by Phillips 

 (1964); this is well within the range of published 

 values for other members of the genus. Age of 

 settlement has been estimated to be 6 mo for S. 



~~**\ A, 



CO 5 



s 



n 

 10 

 5 



10 

 5 



15 

 10 

 5 



" r^ rp 



K 



N 



DEC (43) 



AW, 



_2 8_S_ 



i r 





r~~A 



r~M f»./ 



T 



A, 



rt.ri 



I 1 rN 



n A n r* /V*! 



f I 



■f^A 



' 1 — 



.r^Av^N 



1M A »-< 



.r~*Vi /Vs 



NOV (35) 



— I 



OCT (53) 



SEP (63) 



AUG (84) 



JUL (36) 



JUN (50) 



MAY (98) 



APR (65) 



AvfH 



MAR (194) 



M« 



^ 



"f^- 



FEB (64) 



/^ 



JAN (88) 



i_ 



I n 1 1 1 1 1 r 



10 20 30 40 50 



STANDARD LENGTH (mm) 



FIGURE 1. — Monthly size distribution for surface prejuvenile 

 Sebastes diploproa from the combined dip net collections of 

 1975-76. Parenthetical numbers indicate numbers of fish col- 

 lected in that month. 



umbrosus (Chen 1971), 4 or 5 mo for S. marinus 

 (Kelly and Barker 1961), and 6-12 mo for S. 

 alutus (Westrheim 1973; Carlson and Haight 

 1976). 



Female S. diploproa are ovoviviparous, releas- 

 ing yolk sac larvae from February to July off 

 California (Phillips 1964). The abundance of 

 newly transformed prejuveniles (10-14 mm SL) in 

 August through December indicates that the prin- 

 cipal parturition season occurred in the latter part 

 of this interval (Figure 1). The presence of small 

 individuals in February and March, however, may 

 indicate that there were two principal parturition 

 seasons. Westrheim (1975) provided evidence for 

 two parturition seasons in 1973 off British Colum- 

 bia (July and October-December) and suggested 

 that this species might release larvae throughout 

 the year. 



Surface prejuveniles in the correct size category 

 for settlement were present throughout the year 

 but their abundance was greatest in late spring to 

 early summer. The percentage of specimens larger 

 than 40 mm SL peaked in May and dropped off 

 rapidly thereafter (Figure 2), suggesting that 

 emigration from surface waters occurred primar- 

 ily in May and June. For comparison, seasonal 

 abundance of pelagic prejuveniles of three other 

 Sebastes species are shown (Figure 3). Emigration 

 from surface waters occurred in January to Feb- 

 ruary for S. rubrivinctus , May to June for S. 

 paucispinis , and July to August for S. serriceps. 



Benthic juvenile S. diploproa occurred in a 

 highly clumped distribution (variance exceeded 

 mean number offish per trawl for all months with 

 more than one trawl). Since several months were 

 undersampled or lacked a sufficient number of 

 trawls, data were combined by 2-mo intervals 

 (Figure 4). Small benthicjuveniles first appeared 

 in July-August; abundance peaked in 

 November-December and tapered off thereafter. 



JAN ' FEB ' MAR ' APR T MAY ' JUN ' JUL ' AUG ' SEP ' OCT ' NOV DEC 



MONTH 



FIGURE 2. — Percentage of surface prejuvenile Sebastes diplop- 

 roa >40 mm SL from the combined dip net collections of 1 975-76. 



888 



