PKARCY and HANCOCK: FEEDING HAHITS OF FOUR FLATFISH SPECIES 



Table l. — Percent by weight that major food taxa composed of 

 the diet of the four flatfishes, all stations and seasons combined. 



T.\BLE 2. — Average frequency of occurrence of principal prey 

 (those occurring in S'c or more of the observations) in the four 

 species, all stations combined. 



pleura were principal prey of rex but not Dover 

 sole. Gammarid amphipods occurred frequently in 

 stomachs of both rex and Dover soles; had they been 

 identified to species, the overlap between the diets 

 of the Dover and rex soles would appear even small- 

 er. Overlap in the diets of Dover and rex soles 

 of various size groups were also found to be small. 

 Gammarid amphipods, the major crustacean 

 prey of Dover and rex soles, were not principal 

 prey for slender sole and Pacific sanddab. Slender 

 sole and Pacific sanddab fed largely on pelagic 

 crustaceans, as indicated by the occurrence of 

 euphausiids in stomachs of both species, by crab 

 larvae and calanoid copepods in sanddab, and by 

 Pcimkdusjordani in slender sole. Slender sole and 



Pacific sanddab are chiefly pelagic feeders. Pan- 

 dalus jordani is known to migrate off the bottom at 

 night (Pearcy 1970) and hence could have been 

 consumed on the bottom or in midwater by slender 

 sole. We have occasionally caught both slender 

 sole and Pacific sanddab in midwater trawls at 

 night. Barss"* caught in midwater trawls at night 

 Pacific sanddab that had been feeding heavily on 

 northern anchovy, Engraulis mordax. The only 

 good evidence for benthic feeding by either of these 

 two species is the presence of annelids in their 

 diets (Table 1). 



Differences Among Stations 



The proportions (by weight) of the major taxa in 

 the diet of Dover sole were sometimes markedly 

 different among stations (Table 3). Prey composi- 

 tion and availability may be functions of sediment 

 and/or depth. Annelids constituted over 907f of the 

 diet on a weight basis at the three deepest stations 

 (2, 6, and 8), but <13'^ at the shallowest station 

 (22) where the sediment was well-sorted sand. At 

 this shallow station, mollusks and crustaceans 

 were the major food items in the diet. Coelenter- 

 ates ( feeding polyps of sea pens and anemones) and 

 echinoderms (brittlestars) were minor food taxa 

 for Dover sole at all stations except Stations 15 

 and 23 ( 102 m depth), where together they com- 

 posed over one-half the diet. The proportion offish 

 with food in their stomachs was also higher at 

 these two stations than at any of the other sta- 

 tions. 



To illustrate the similarities of the food habits of 

 Dover sole among these stations, we constructed a 

 station-station matrix (Table 4) using an index 

 ( C ^) that Horn ( 1966) recommended for comparing 

 overlap in exploitation of alternative food sources 



''Barss, W. H. (compiler). 1976. The Pacific sanddab. Oreg. 

 Dep. Fish Wildl., Inf Rep. 76-5, 5 p. 



Table 3. — The average percentage composition of stomach con- 

 tents of Dover sole on a weight basis at each of the stations. 



643 



