FISHERY BULLETIN: VOL. 84, NO. 3 



63 00N 



■- 61 00N 



59 00N 



- 57 00N 



55 00N 



- 53 00N 



5) OON 



179 OOE 



1 76 OOW 



171 OOW 



166 OOW 



161 OOW 



56 OOW 



Figure 1.— Sampling locations for arrowtooth flounder, Atheresthes stomias, and Kamchatka flounder, A. evermanni, in summer 1983 



in the eastern Bering Sea. 



were excised along with the anterior portion of the 

 body (including head, stomach, and intestines), and 

 these samples were sent to the laboratory for species 

 identification. Each specimen was placed in a muslin 

 bag with a specimen label bearing fork length, sex, 

 and station information. All samples were preserved 

 in 10% Formalin 3 . 



In the laboratory, two characters were used for 

 species identification: the position of the left eye 

 relative to the dorsal profile and gill rakers. Kam- 

 chatka flounder has the upper eye completely on the 

 right side of the head and 13 or fewer gill rakers 

 on the first arch. Arrowtooth flounder has an up- 

 per eye which interrupts the dorsal profile of the 

 head and 15 or more gill rakers on the first arch 

 (Norman 1934; Willimovsky et al. 1967). 



3 Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Stomachs were analyzed individually. Prey items 

 were identified to the lowest taxonomic level prac- 

 tical, counted, and weighed damp to the nearest 

 milligram. The standard length of fish prey were 

 also measured. 



DATA ANALYSIS 



Specimens of A. stomias and A. evermanni were 

 divided into 100 mm fork-length groups for data 

 analysis: <201 mm, 201-300 mm, 301-400 mm, and 

 >400 mm. Percent of frequency of occurrence 

 (% FO), percentage of total stomach content weight 

 (% W), percentage of total prey number (% N) and 

 the Index of Relative Importance [IRI = % FO (% N 

 + % W)] (Pinkas et al. 1971) were calculated for ma- 

 jor categories of prey items in the 100 mm size 

 groupings of A. stomias and A. evermanni. 



Based on a review of dietary overlap measures 



616 



