FISHERY BULLETIN: VOL. 85. NO. 1 



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•PALOS VERDES 

 °HUNT1NGT0N BEACH 



61M 



62 53 84 



Figure 4.— Abundances of California scorpionfish taken by trawl off the Palos Verdes 

 Peninsula and Huntington Beach at three depths from 1974 to 1984. 



where the fish went. They did not migrate to deeper 

 waters, as catches did not increase at the deeper sta- 

 tions. It is possible the fish moved north, as we 

 observed a sUght increase in commercial trawl- 

 caught scorpionfish off Santa Barbara, 190 km to 

 the north. The populations of several other species 

 (notably bocaccio, Sebastes paucispinis; chilipepper, 

 S. goodei; and California halibut, Paralichthys 

 californicus) seemed to shift northward during the 

 same period. 



The presence of California scorpionfish over the 

 soft substrata about Palos Verdes (Fig. 4) attests 

 to the habitat plasticity of this species. This abun- 

 dance is unusual. For example, the species is only 

 occasionally found over soft substrata to the imme- 

 diate south (Huntington Beach). We believe the 

 abundance of California scorpionfish over soft sub- 

 strata about Palos Verdes is linked to the large 

 populations of the ridgeback prawn, Sicyonia ingen- 

 tis, and untimately to the presence of the Whites 

 Point sewer outfall. Both we and Cross^ have noted 

 that scorpionfish routinely regurgitate these prawns 

 when captured from waters around Palos Verdes. 



Studies of sediments about the Santa Monica Bay, 

 Palos Verdes, and Huntington Beach outfalls reveal 



*J. Cross, Southern California Coastal Water Research Project, 

 Long Beach, CA, pers. commun. May 1985. 



that substrate deposition of organic material is much 

 greater at Palos Verdes than at the other two sites. 

 This is apparently due to faster water movement 

 and hence greater sewage dispersal at the Santa 

 Monica and Huntington Beach sites (Cross et al. 

 1985; Cross fn. 8). The large quantities of organics 

 in the Palos Verdes sediment support large popula- 

 tions of ridgeback prawns, populations nearly ab- 

 sent from the other two sites. Additional evidence 

 for this contention comes from the creel census data 

 in Figure 1. These data are based on catches over 

 hard bottom reefs, where ridgeback prawns are not 

 abundant. In this study, California scorpionfish were 

 not more abundant at Palos Verdes than at Santa 

 Monica Bay (to the north) or Huntington Beach (to 

 the south), which have similar environmental param- 

 eters. Thus the attraction of the soft substrata 

 around Palos Verdes for scorpionfish is likely to be 

 the one factor which is quite different among the 

 sites— the presence of ridgeback prawns. 



Age and Growth 



Prior to this study, there was no published work 

 on aging California scorpionfish, the use of ptery- 

 giophore sections in age studies had not been vali- 

 dated. To determine if the opaque and translucent 

 zones (as observed by reflected light) were annular, 



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