SINGER: FOOD HABITS OF ROCKFISH 



Table 1.— Taxa of prey identified in the stonnachs of juvenile rockfish; names in all-capitals are categories 

 used in stomach content analysis. (?) signifies incomplete or unsure identification. Microhabitat 

 associations: OW = open water prey, S = substrate oriented prey. 



Table 2. — Mean (+95% confidence interval) sizes of individuals of 

 the nine major prey types of juvenile rockfishes. Measured items 

 were taken from stomach samples. 



similar diets (Fig. 2, Tkble 4). Both species ate mainly 

 open water prey: calanoid copepods, harpacticoid 

 copepods, and zoea larvae in order of importance 

 These species also showed fairly high intraspecific 

 diet variability— 5.3 and 4.4 prey taxa per individual 

 for melanops and serranoides, respectively. 



The two species which showed major microhabitat 

 shifts (Carr 1983), S. caurinus and S. camatus, also 



showed large dietary changes. While in the canopy 

 (generally <45 mm in SL), 5. caurinus ate 

 predominantly calanoid copepods, with harpacticoids 

 and zoea also eaten fairly consistently (Fig. 2). 

 However, after moving out of the canopy and down 

 to the bottom near kelp stipes and rocks, its diet 

 shifted to primarily caridean shrimp, with gammarid 

 amphipods being the second most important prey 

 (Fig. 2). Sebastes camatus showed much the same 

 type of dietary shift accompanying its large habitat 

 shift. While in the canopy, smaller S. camatus ate 

 nearly exclusively calanoid copepods (92% of the 

 diet), while large individuals, which were found on 

 the bottom, fed on caridean and mysid shrimp and 

 isopods (Fig. 2). This marked change in diet can also 

 be seen in Tkble 4. Within each of these species, the 

 diet similarity between size classes was low. However, 

 similarities between the two species within each size 

 class was quite high. 



Sebastes atrovirens was found in the kelp canopy 

 and among kelp throughout all depths during the 

 entire study (Carr 1983). This species fed mainly on 

 gammarid amphipods, with calanoid and harpac- 

 ticoid copepods and mysid shrimp also being very 



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