FISHERY BULLETIN: VOL. 82, NO. 1 



and Zerba (1981) utilized two divers, swimming 

 parallel, unmarked courses and counting fish be- 

 tween each other, to sample rocky-reef fishes. 

 Perhaps such a method could be used to evaluate 

 densities estimated in cinetransects. 



Species Composition, Distribution, 

 and Abundance 



The species observed in the San Onofre kelp forest 

 were a subset of the species found in other nearshore 

 areas of hard substrate and vegetation off southern 

 California. Many reef-dependent fishes that are very 

 common in other kelp forests were either rare or 

 unrecorded at San Onofre. Species such as black- 

 smith and opaleye (Ebeling and Bray 1976; Hobson 

 and Chess 1976), garibaldi (Clarke 1970), painted 

 greenling (DeMartini and Anderson 1979), and some 

 species of Sebastes (Larson 1980) depend on rugose 

 reefs for shelter or spawning sites. Some turf-grazing 

 and otherwise bottom-feeding species of embi- 

 otocids also appeared to be less abundant at San 

 Onofre than in other areas. Our estimates of 14-37 

 kg/ha of pile perch, 38-78 kg/ha of black perch, and 

 10-18 kg/ha of rubberlip seaperch were mostly 

 smaller than the estimates of Ebeling et al. (1980b) 

 off Santa Barbara and Santa Cruz Island. The rarity and 

 low abundance of all these species markedly alters 

 the character of the fish assemblage at San Onofre. 

 The abundant species at San Onofre kelp forest 

 either are less dependent on rock reefs (at least, if 

 kelp is present) or associate preferentially with low- 

 relief substrates. The former group might include the 

 canopy species, the cosmopolitan kelp bass and 

 sehorita, and perhaps the epibenthic California 

 sheephead. The latter group might include barred 

 sand bass and white seaperch. These two species 

 (and perhaps sehorita) were more common at San 

 Onofre than others (Ebeling et al. 1980a, b) have 

 reported in kelp forest anchored on high-relief sub- 

 strates. Barred sand bass occurred in over half of the 

 bottom transects at SOK, but in no more than 12% of 

 bottom transects near Santa Barbara (Ebeling et al. 

 1980a). We found white seaperch in 40-60% of our 

 transects, while Ebeling etal. (1980a) saw them on 7- 

 42% of all transects (but 20-42% of "sandy margin" 

 transects). Both of these species have been reported 

 as associating with sand or the sand-rock interface 

 (Quast 1968a; Feder et al. 1974; Ebeling et al. 

 1980a). Moreover, barred sand bass have a 

 warmwater affinity (Frey 1971) and on average 

 should be more abundant farther south in the 

 Southern California Bight. The abundance of white 

 seaperch at SOK may be unusually high during the 



fall. At this time, white seaperch appear to use the 

 SOK habitat for mating as well as feeding. While 

 some individuals of white seaperch are found in kelp 

 forests all year, much of their populations in kelp 

 beds off northern San Diego County move offshore 

 after fall (authors' observations). 



The vertical distributions of species present at the 

 San Onofre kelp bed were similar to patterns de- 

 scribed in other kelp forests. Kelp perch, giant 

 kelpfish, and, to a lesser extent, halfmoon have been 

 recognized as water-column and canopy species 

 (Quast 1968a; Feder et al. 1974; Bray and Ebeling 

 1975; Ebeling and Bray 1976; Hobson and Chess 

 1976; Coyer 1979; Ebeling et al. 1980a, b). Kelp bass 

 and white seaperch have been described as members 

 of a vertical "commuter" group of fishes in kelp 

 forests near Santa Barbara (Ebeling et al. 1980a). 

 The term "cosmopolite" better describes the habits 

 of these two fishes. Sehorita also fell into Ebeling et 

 al.'s "canopy" group, but its occurrence throughout 

 the water column was recognized by Hobson (1971), 

 Ebeling and Bray (1975), Bernstein and Jung (1979), 

 and others. We feel that it too should be considered a 

 cosmopolite. Pile perch and rubberlip seaperch were 

 also assigned to the commuter group of Ebeling et al. 

 (1980a) and did appear above the bottom at San 

 Onofre. However, the dense midwater aggregations 

 of these species observed elsewhere were not present 

 at San Onofre. Perhaps the relatively low density of 

 these species at San Onofre was responsible for the 

 absence of these aggregations. On the other hand, 

 our fairly frequent observation of California 

 sheephead well above the bottom is apparently new. 

 Quast (1968a), in fact, noted that sheephead seem 

 "reluctant" to leave the bottom. Barred sand bass, 

 black perch, rainbow seaperch, and rock wrasse 

 occurred almost exclusively on the bottom, and have 

 been generally recognized as bottom dwellers. 



Our estimates of vertically integrated standing 

 stock were surprisingly high. Most estimates of fish 

 biomass on tropical and temperate reefs fall into the 

 range of a few to several hundred kg/ha (Brock 1954; 

 Bardach 1959; Randall 1963; Quast 1968b; Talbot 

 and Goldman 1972; Miller and Geibel 1973; Jones 

 and Chase 1975; Russell 1977). It is encouraging that 

 our estimates of 3.88-6.53 kg/100 m 2 (388-653 kg/ 

 ha) fell within this range. Furthermore, our density 

 estimates for fall 1979 are generally similar to subse- 

 quent estimates made for canopy and bottom strata 

 during the fall periods of 1980 and 1981 (E. DeMar- 

 tini 7 Unpubl. data). In particular, the densities of resi- 



7 E. DeMartini, Marine Science Institute, University of California, 

 Santa Barbara, CA 93106. 



50 



