EBELING and BRAY: ACTIVITY OF REEF FISHES 



86-244 mm); striped seaperch, E. lateralis (200, 

 110-280); rubberlip seaperch, Rhacochilus toxotes 

 (279, 165-400); pile perch, Damalichfhys vacca (210, 

 97-260); and rainbow seaperch, Hypsurus caryi 

 (159, 114-253). Immediately after each dive, in- 

 dividuals were either iced and later frozen, or slit 

 ventrally and fixed in 10% Formalin. ^ The 

 procedure for gut analysis followed the method of 

 Bray and Ebeling (1975), except that the 

 surfperch's gut, which is simple and tubular and 

 lacks a well defined "stomach," was divided into 

 quarters. Fullness of the "foregut," defined as the 

 first quarter of the length of the entire gut, was 

 scored subjectively from 1 (empty) to 5 (full), and 

 plotted against time of collection. Since fish were 

 sampled throughout the year, their times of col- 

 lection were seasonally adjusted relative to actual 

 times of sunrise and sunset as determined from 

 solar tables. 



RESULTS 



We identified 25 species of fishes from 21 paired 

 day-night transects made between April 1972 and 

 September 1973. Most of the fishes seen along the 

 transect line were adults. The only abundant 

 juveniles were of the blue rockfish, Sebastes mys- 

 timis. Hence for blue rockfish only, juveniles and 

 adults were counted separately. We excluded from 

 the analysis all species that could not be consis- 

 tently observed, such as some of the more cryptic 

 and secretive fishes that blend with their sur- 

 roundings and hide in kelp and rocks, and species 

 that occur only near the water surface outside our 

 field of vision. 



It appeared that our visual counts adequately 

 sampled all of the more conspicuous kelp-bed 

 fishes. The rank order of abundance of fishes 

 recorded in the 21 daytime transects was highly 

 correlated with that of fishes observed in a photo- 

 graphic survey consisting of 125, 2.5-min motion 

 pictures (Ebeling, Larson, and Alevizon unpubl. 

 data) filmed over the same area (Kendall's tau 

 coefl^cient of rank correlation = 0.65; P <0.001). 



The species composition of seasonally pooled 

 samples and the relative abundances of the dif- 

 ferent species varied surprisingly little during the 

 17-mo study period. Almost all species were seen 

 throughout the year, and rank orders of species 

 abundances, pooled over day and night samples, 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



were significantly concordant among seasonal 

 periods that correspond roughly to annual oceano- 

 graphic periods defined by Brown (1974) (Table 2). 



During the day, almost 4,000 fishes representing 

 11 families of teleosts and 1 family of sharks were 

 counted along the transect line. The two dominant 

 groups-surfperches (Embiotocidae) and rock- 

 fishes (Sebastes) -were represented by six species 

 each. The most abundant species was 5. mystinus 

 whose juveniles accounted for 44% of the in- 

 dividuals sighted during the day (Table 3). 



Most individuals of all species of fishes (66%) 

 were observed in the mid-water zone higher than 1 

 m off the bottom (Table 4). The two most abundant 

 species in the mid-water zone, S. mystinus and 

 Chromis punctipinnis often formed large, mixed 

 aggregations above rocky prominences and 

 around columns of giant kelp. Besides S. mystinus 

 and C. punctipinnis, more than 80% of the in- 

 dividuals in several other species were observed in 

 the mid-water zone: the kelp bass, Paralabrax 

 dathratus; Oxyjidis californica; opaleye, Girella 

 nigricans; and S. serranoides (Table 4). But 10 of 

 the total of 19 species recorded from the mid-water 

 zone were more abundant in other zones. 



Some 25% of the total individuals of all species 

 were observed in the suprabenthic zone, within 1 

 m of the rocky bottom (Table 4). This zone included 

 the most species (21) and was dominated by 

 surfperches: 71% of the individuals observed in the 

 suprabenthic zone were surfperches, as compared 

 with but 12% in the mid-water zone. Nearly half 

 the individuals were Embiotoca jacksoni or E. 

 lateralis. 



Less than 10% of the total individuals recorded 

 during the day were observed either in the bottom 

 zone, contacting the reef in an exposed position, or 

 in the shelter zone, occupying a crevice or hole 

 (Table 4). Most of these were demersal, 

 "ambusher-type" predators, e.g., rockfishes and 

 sculpins (Cottidae), although a few of the mid- 

 water species, e.g., S. mystinus and C. punctipin- 

 nis, were also observed in these zones in small 

 numbers. 



We recorded substantially fewer individuals at 

 night than during the day (Table 3). Day to night 

 decreases in total numbers were consistently 

 significant among the 21 pairs of day-night sam- 

 ples (Wilcoxon signed-ranks test for paired 

 observations, P<0.005). Also, lists of species, 

 ranked by abundance, differed at night. All 21 rank 

 correlations for the day-night sample pairs (tau = 

 -0.32 to -1-0.22), as well as the single rank correla- 



705 



