ioo r 



S; rubrivinctus 

 ^ poucispims 

 S. semceps 



FIGURE 3. — Monthly abundance of surface prejuveniles of 

 Sebastes rubrivinctus, S. paucispinis, and S. serriceps from the 

 combined dip net collections of 1975-76. 



40r— 



30 



5*20 



1-5 



CD ~ 

 < 



10 



JUL/AUG [ SEP/OCT | NOV/DEC 1 JAN/FEB | MAR/APR |MAY/JUN | JUL/AUG I 

 (3) (13) (29) (6) (12) (33) (3) 



INTERVAL 



FIGURE 4. — Bimonthly abundance ( number caught per trawl ) of 

 benthic juvenile Sebastes diploproa from trawl collections of 

 1972 through 1976. Circles represent abundance of all specimens 

 <50 mm; triangles, all <60 mm. Parenthetical numbers indicate 

 the number of trawls made per interval. 



Discussion 



Surface size distribution and abundance data 

 indicate that the bulk of emigration from the sur- 

 face occurred in late spring to early summer (Fig- 

 ures 1, 2), whereas appearance of benthic juveniles 

 began in midsummer and continued over a period 

 of several months (Figure 4). The temporal dis- 

 crepancy between disappearance from the surface 



and peak benthic appearance suggests that mig- 

 rant juveniles may occupy an intermediate 

 habitat between emigration and settlement. Dur- 

 ing this period, the juveniles are probably in mid- 

 water, as shown for S. macdonaldi by Moser 

 (1972). Four specimens of S. diploproa have been 

 taken in two discrete-depth midwater trawls by 

 the RV Velero IV and are presently in the fish 

 collection of the Natural History Museum of Los 

 Angeles County (LACM). Three of these speci- 

 mens (43, 47, 48 mm SL) were captured in October 

 1970 at a depth of 250 m off San Clemente Island 

 (lat. 32°39'N, long. 118°11'W; LACM 36315-1); 

 the fourth specimen (43 mm SL) was taken in 

 December 1970 at a depth of 200 m off Santa 

 Catalina Island (lat. 33°21'N, long. 118°46'W; 

 LACM 36307-1). Both tows were taken between 

 0200 and 0430 (local time) over bottom depths of 

 1,915 and 1,280 m, respectively. Since these bot- 

 tom depths greatly exceed the bathymetric range 

 for S. diploproa, time may be spent in horizontal 

 movement to benthic habitat of suitable depth. 

 Early migrants may come from nearshore areas, 

 such as those sampled in the dip net collections, 

 whereas those appearing later in the year may 

 come from offshore prejuvenile populations; larval 

 Sebastes are known to be distributed hundreds of 

 kilometers offshore (Ahlstrom 1961). 



Southern California is near the southern end of 

 the geographic range for S. diploproa (Phillips 

 1964); no information was available on the surface 

 prejuveniles of this species from the center or 

 northern parts of its range. Extension of the tim- 

 ing of emigration and subsequent appearance in 

 the benthic habitat is probably a direct result of 

 the long parturition season off California. Westr- 

 heim (1975) has shown that two parturition sea- 

 sons may occur per year off British Columbia and 

 has suggested that limited year-round spawning 

 may take place. In general, however, as one goes 

 further north, the principal parturition season is 

 progressively shorter and later; off Oregon, the 

 season is mid-May to June (Hitz 1962), June to 

 July off Washington ( DeLacy et al. 1964), and July 

 off British Columbia (Westrheim 1975). I would 

 expect surface prejuvenile year classes to be more 

 distinct in the north than shown in my data (Fig- 

 ure 1), and that timing of emigration from surface 

 waters would be more precise. 



Acknowledgments 



I thank M. J. Allen of the Southern California 



889 



