FISHERY BULLETIN: VOL. 74, NO. 3 



aggregations of juveniles more than 30 min before 

 sunrise. Of these, 13 (72%) were full of prey in 

 varying stages of digestion, demonstrating noc- 

 turnal feeding, whereas 5 (28%) were empty, 

 indicating they had been inactive that night. All 

 the empty fish were from the developing ag- 

 gregations, but many of those containing food 

 were also taken from those aggregations. Items 

 taken at night by the 13 intermediate juveniles 

 containing food were as follows, with the format 

 being that used for the small juveniles, above. 



1. GAMMARIDEAN AMPHIPODS (69: 2.9: 28.5) 



including Batea transversa and Ericfhonias braziliensis. 



2. CUMACEANS (54: 2.7: 26.3) 



Cycla.'^pis nxhila (46: 2.6: 26.1); Cumella sp. A (8: 0.1: 0.2). 



3. MYSIDS(38:?: 16.2) 



Siriella pacifica (23: 0.3: 13.1); unidentified fragments (15: ?: 

 3.1). 



4. FISHES (15: 7.1: 5.4) 



unidentified larvae. 



5. CAPRELLID AMPHIPODS (8: 0.5: 6.2) 



Caprella pilidigita. 



6. POLYCHAETES, SWIMMING (8: ?: .5.0) 



unidentified fragments. 



7. OSTRACODS (8: 0.1: 0.8) 



Paraaterope sp. A 



8. BRACHYURAN MEGALOPS (8: 0.5: 0.4) 



unidentified. 



The diurnal feeding situation, as well as the 

 changeover from day to night, is represented by 12 

 individuals (55-62 mm, x = 58), all with full guts, 

 collected from among feeding aggregations of 

 small juveniles within 1 h after sunrise. Almost all 

 the food items in this sample were either fresh or 

 well-digested-there was little in between. Pre- 

 sumably, the fresh items were those that had been 

 taken after feeding began within the previous 

 hour, whereas the extensively damaged items had 

 been taken during the night before. (One would 

 expect specimens taken as early in the morning as 

 these to contain evidence of any nocturnal feeding 

 they might have done, and this proved true here.) 

 Seven of the 12 individuals sampled contained 

 both fresh and well-digested material in large 

 numbers, always with the fresh items forward in 

 the gut (often in the esophagus), and the well- 

 digested items well back in the posterior region. 

 Clearly, these individuals had fed substantially 

 during both day and night (a conclusion strength- 

 ened by the kinds of prey among the fresh and 

 well-digested segments of the diet, see below). 

 Three of the other five specimens contained only 

 fresh items, indicating diurnal feeding exclusive- 

 ly, whereas two contained just well-digested ma- 



terial, indicating only nocturnal feeding. Food 

 items in this material are identified below, but 

 with fresh items listed separately from well- 

 digested items. 



FRESH ITEMS 



1. CALANOID AND CYCLOPOID COPEPODS (83: 65.9: 47.8) 



calanoids (83: 65.7: 47.5); cyclopoids (17: 0.2: 0.3). 



2. CLADOCERANS (33: 0.8: 0.8) 



Evadne sp. 



3. OSTRACODS (8: 0.1: 1.7) 



Cycloleberis lohiancoi. 



4. OTHER COPEPODS (8: 0.1: 0.4) 



monstrilloids. 



5. ISOPODS(8:0.1:0.4) 



gnathiid juveniles. 



6. HARPACTICOID COPEPODS (8: 0.2: 0.2) 



Porcellidium sp. A. 



7. CARIDEAN LARVAE (8: 0.1: 0.3) 



unidentified. 



WELL-DIGESTED ITEMS 



1. GAMMARIDEAN AMPHIPODS (.50: 1.3: 1.1) 



including Batea transversa. 



2. CARIDEAN LARVAE (33: 2.2: 12.9) 



unidentified. 



3. EUPHAUSID ADULTS AND JUVENILES (17: 0.7: 10.7) 



unidentified fragments. 



4. FISHES (17: 1.0: 9.2) 



unidentified larvae. 



5. REPTANTIANZOEA(17:0.3:2.0) 



unidentified. 



6. BRACHYURAN MEGALOPS (8: 0.3: 1.3) 



unidentified. 



7. INSECTS (8: 0.1: 0.8) 



unidentified. 



8. CAPRELLID AMPHIPODS (8: 0.1: 0.4) 



unidentified. 



The fresh items apparently represent diurnal 

 feeding, the well-digested items nocturnal feed- 

 ing. Thus, among individuals within the inter- 

 mediate size range there obviously are many that 

 forage during both day and night. 



LARGE JUVENILES.-During the day, olive 

 rockfish more than about 65 mm long generally 

 hovered in small aggregations low in the water 

 column beneath the kelp canopy within the 

 seaward part of the forest (Figure 6). Aggrega- 

 tions composed of relatively large individuals 

 (exceeding a length of about 100 mm) sometimes 

 hovered above others of the same size seated on 

 the rocks below. 



In contrast to the small individuals described 

 above, large juveniles generally showed no sign of 

 feeding during the day, an observation supported 



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