776 



Fishery Bulletin 94(4). 1996 



samples from May to July 1992 and 

 only 29 individuals (0.5% of total 

 catch) occurred in 65 midwater trawl 

 samples from May to July 1993 (Loeb 

 et al. 1 ). 



Discussion 



Larval rockfish are a dominant group 

 in the ichthyoplankton along the 

 west coast of the United States, with 

 relatively high abundances occurring 

 seasonally in surveys off southern 

 and central California (Barnett et al., 

 1984, Moser and Boehlert, 1991) and 

 off northern California, Oregon, and 

 Washington (Richardson and Pearcy, 

 1977; Richardson et al., 1980; Boehlert 

 et al., 1985; Doyle et al., 1993). Dur- 

 ing our study, mean overall abun- 

 dance of larval rockfish ranked sec- 

 ond only to that of the northern an- 

 chovy (Engraulis mordax; 749 lar- 

 vae/10 m 2 ) in 1992 and Pacific hake 

 (Merluccius productus; 1,520 larvae/ 

 10 m 2 ) in 1993 (B. Daly, unpubl. 

 data). Larval rockfishes are gener- 

 ally characterized as meitbers of off- 

 shore assemblages; their abundance 

 increased with distance from shore 

 in our study as well as in the sur- 

 veys cited above. Distribution of at 

 least the youngest larvae is defined 

 by the location of spawning adults, 

 which for many rockfish species is 

 principally over rock bottom along 

 the edge of the continental shelf and 

 submarine canyons. This is sup- 

 ported by the significantly greater 

 numbers of small shortbelly rockfish 

 larvae in samples collected at our 

 most offshore station, located over 

 Ario Nuevo submarine canyon. 



Declines in somatic and reproduc- 

 tive condition (VenTresca et al., 1995) 

 and decreased fat storage (Lenarz 

 and Wyllie Echeverria, 1986) in adult 

 rockfish collected off central Califor- 

 nia during El Nino years likely are 

 responses to reduction in primary 

 prey biomass. Mullin and Conversi 

 ( 1989) documented large-scale reduc- 

 tions in abundance of euphausiids 

 and smaller zooplankton (e.g. the pri- 



