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Fishery Bulletin 90(3). 1992 



(e.g., predation, advection, etc.). 

 Regardless of the mechanism, 

 variation in the availability of 

 food can have a major effect on 

 year-class strength (Lasker 

 1981). The study of food utiliza- 

 tion patterns and diet overlap is, 

 therefore, useful in understand- 

 ing survival mechanisms during 

 the pelagic juvenile life stage. 

 Moreover, annual variation in 

 the extent of interspecific dietary 

 overlap may indicate changes in 

 the distribution and abundance 

 of prey (e.g., Zaret and Rand 

 1971). Since this may well be 

 critical in determining the suc- 

 cess of a year-class, similarity in 

 food habits among pelagic juve- 

 nOe rockfish may result in similar 

 recruitment dynamics. 



Previous published dietary 

 studies of juvenile rockfish have 

 been limited to (1) experimental 

 work on food ration and growth 

 in black rockfish (S. melanops, 

 Boehlert and Yoklavich 1983); (2) 

 a description of the diet of new- 

 ly settled Pacific ocean perch 

 (S. alutus, Carlson and Haight 

 1976); (3) a comparison of the 

 food habits of seven Sebastes spp. in a nearshore kelp- 

 forest habitat (Singer 1985); and (4) predation on bar- 

 nacle larvae by a mixed assemblage of settled kelp resi- 

 dent juvenile rockfishes (Gaines and Roughgarden 

 1987). The purpose of this study was to examine the 

 feeding ecology of several co-occurring young-of-the- 

 year pelagic juvenile rockfishes, including widow rock- 

 fish S. entomelas, yellowtail rockfish S.Jlavidus, chili- 

 pepper iS. goodei, shortbelly rockfish S. jordani, and 

 bocaccio S. paucispinis. Specific goals of this study 

 were to (1) identify the food habits of these five species 

 during the pelagic juvenile stage, (2) determine the ex- 

 tent of dietary overlap among the five species, and (3) 

 determine the degree of interannual variation in pat- 

 terns of prey utilization. 



Materials and methods 



Juvenile rockfish used in this study were obtained from 

 midwater trawl samples made during a series of an- 

 nual pelagic juvenile rockfish surveys conducted off 

 central California during 1984-87. Details of these 

 surveys are described in Wyllie Echeverria et al. (1990). 



The primary purpose of the surveys was to estimate 

 the distribution and abundance of the pelagic-stage 

 juveniles of age-0 rockfishes. Survey areas and dates 

 differed somewhat from year to year (Fig. 1, Table 1). 

 The surveys were conducted during June, except in 

 1987 when the survey extended from late-May to June. 

 In 1984 and 1985, the survey area extended from Point 

 Sur Oat. 36°18'N) to Point Cabrillo Oat. 39°20'N). Bot- 

 tom depths at each trawl station ranged from <50m 

 at nearshore localities to > 3700 m beyond the continen- 

 tal shelf. The sampling plan was revised in 1986; seven 

 transects composed of 36 stations were selected based 

 on previous records of rockfish abundance and the 

 availability of ship time. These stations were sampled 

 repetitively during three consecutive sweeps of the 

 area. After 1985, the survey area extended from 

 Cypress Point Oat. 36°35'N) to Point Reyes Oat. 38° 

 OO'N), with station depths ranging from <50 to 1000m. 

 Collections were made from the RV David Starr Jor- 

 dan with a modified Cobb midwater trawl net having 

 a 24.4m head rope and 0.76cm mesh liner in the cod- 

 end. The standard depth sampled was 30 m. However, 

 at shallow stations Osottom depth < 100 m) the net was 

 set at 5- 10 m. At some deep stations samples were 



