FISHERY BULLETIN: VOL. 76, NO. 1 



Table 4. — Numbers of the three species of kelp-bed fishes in the 

 151- to 300-mm size group (Table 1, Figure 1) from Naples Reef 

 or One-Mile Reef (olive rockfish only) that contained more than 

 95% (by volume) of items composing prey types (plankton, P; 

 nekton, N; or substrate-oriented prey, SOP) listed in Table 2. 



were less clear. Kelp bass ate tunicates from De- 

 cember to May, but fish, kelp, and hydroids were 

 important prey for much of the year. Olive rockfish 

 from Naples Reef ate mostly fish throughout the 

 year. 



To test for seasonal differences in diet, the fre- 

 quencies of prey types were subjected to chi-square 

 tests of homogeneity calculated from contingency 

 tables of dimension two (presence or absence) by 

 four (seasonal periods). Plankton frequencies were 

 significantly heterogeneous, with highest values 

 during winter-spring periods (Figure 2). As fewer 

 kelp bass and olive rockfish ate plankton during 

 the year, more ate nekton, primarily small fish. 

 More blue rockfish and kelp bass ate more algae 

 (with encrusting animals) later in the year. 



Species showed greater overlap in diet during 

 periods when their stomachs were fuller of prey 

 (Table 6). For all species, both stomach fullness 

 and food overlap were greater during summer-fall 

 than during winter-spring (Table 6). Fullness may 

 relate to greater exploitation of nekton during 

 summer-fall (Figure 2). For all species, stomachs 



Table 5. — Seasonal variation in diets of the three species of kelp-bed fishes in all size groups (Figure 1) from Naples Reef or One-Mile 

 Reef (olive rockfish only) off Santa Barbara, Calif. The first five ranking food items with their percent volimie are listed in order for each 

 time period. Sample size is the number of diets (fish) pooled per period; W is Kendall's "Vf" rank concordance (Tate and Clelland 1957) 

 among seeisons for (n) total items. 



Table 6. — Seasonal variation in stomach fullness and interspecific dietary overlap in the three species of kelp-bed 

 fishes in all size groups (Figure 1) from Naples Reef off Santa Barbara, Calif Stomach fullness is mean score, from 

 1.0 (empty) to 5.0 (full and distended). Food overlap with species in next row down is defined in the text. 



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