FISHERY BULLETIN: VOL. 76, NO. 3 



consumed by the rex sole and Pacific sanddab 

 caught in a single collection off the central Oregon 

 shelf. This study is, to our knowledge, the most 

 complete study of the food habits of these four 

 species. 



METHODS 



Fishes were collected during 115 tows with a 

 3-m beam trawl at seven stations on the continen- 

 tal shelf off central Oregon between August 1968 

 and August 1970. These stations are classified by 

 four depth categories and the percentage of sand in 

 the sediments in Figure 1 . Details on methods and 

 descriptions of the stations are given by Pearcy 

 (1978). 



All fishes were preserved at time of capture with 

 Formalin,-' and the body wall of large (>150-200 

 mm SL) fishes was incised to insure preservation 

 of stomach contents. Fishes were identified and 

 measured (standard length, SL) in the shore 

 laboratory. Stomachs were removed from 326 

 Dover sole represented in the catches at all seven 

 stations; and from 614 rex sole, 1,109 slender sole, 

 and 723 Pacific sanddab captured at two or three 

 stations where each of these species was most 

 common. 



Stomach contents were removed and empty 

 stomachs were noted. Food organisms were iden- 

 tified to species when possible. Annelids, crusta- 

 ceans, mollusks, echinoderms, coelenterates, and 

 remaining taxa (major taxa) were weighed to the 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



DEPTH (m) 



100- 190- 



74 102 148 195 



< 



CO 



u 

 u 



UJ 



20 



60 



75 



100 



Figure l, — Classification of the seven stations, each indicated 

 by station number, according to depth of water and percent of 

 sand (0-20, 20-60, 60-75, and 75-100^^ ). The stations with similar 

 sediment types but different depths are 6 and 8, 7 and 2, and 22 

 and 15. (See Pearcy 1978 for additional information.) 



nearest 0.01 g (wet-preserved weight). Usually 

 these weights were obtained for the contents of a 

 single stomach, but when the contents were in- 

 sufficient for accurate weighing, taxa from the 

 stomach contents of several fish of the same 

 species and size, and from the same tow, were 

 combined and weighed together to constitute an 

 observation. The number of observations for 

 Dover, rex, and slender sole and Pacific sanddab 

 were 325, 374, 607, and 392, respectively. 



Results are reported as the a) percent that each 

 major food taxa constitutes of the total wet weight 

 of food found in stomachs for all seasons combined 

 and for winter and summer seasons separately; 

 and b) the frequency of occurrence (FO) of princi- 

 pal prey, i.e., species or taxa found in 59^ or more of 

 the observations for a species or size group of a 

 species for all seasons combined. 



RESULTS 



General Food Habits 



Two general feeding types are indicated by dif- 

 ferences in the weights of major food taxa (an- 

 nelids, crustaceans, mollusks, echinoderms, 

 coelenterates, and other taxa) found in the 

 stomach contents of the four species (Table 1). 

 Dover and rex soles fed largely (64^ ) on annelids, 

 while slender sole and Pacific sanddab fed mainly 

 on crustaceans (75'7r ). Within these two apparent 

 feeding types, differences occurred among the 

 proportions of prey taxa of secondary importance. 

 For example, crustaceans were more abundant in 

 the diet of rex than Dover sole (31% vs. 11%), 

 whereas mollusks were more abundant in Dover 

 than in rex sole ( 18% vs. I9t ). Annelids composed 

 more of the stomach contents of slender sole than 

 Pacific sanddab (159^ vs. 7% ). 



Based on the average frequency of occurrence of 

 principal prey (F0>5% ) from all sizes offish and 

 from all stations (Table 2), it is obvious that the 

 food habits within these two feeding types (Dover 

 sole-rex sole vs. slender sole-Pacific sanddab) are 

 not as similar as shown by Table 1. Principal prey 

 of Dover sole, for example, included 11 different 

 identified polychaetes. Rex sole preyed mainly on 

 three identified species of polychaetes. Only one 

 principal prey species of polychaete was common 

 to the diet of both Dover and rex soles. The shrimp 

 Pandalus Jordani, pelecypods, and ophiuroids 

 were principal prey in the food of Dover but not rex 

 sole, whereas crab larvae, cumaceans, and Oiko- 



642 



