FISHERY BULLETIN: VOL, 76, NO. 3 



Table 4. — Similarity iCj^) in the diets of Dover sole at the seven 

 stations based on the percentage of major taxa in their diets on a 

 weight basis (below diagonal) and frequency of occurrence of 

 principal polychaete prey (above diagonal). Stations are ar- 

 ranged by depth. 



Stations 



22 



Frequency of occurrence 

 15 23 6 



22 

 7 

 15 

 23 

 6 

 2 

 8 



0.21 



088 



043 



0.53 



1.00 



1 00 



within the same habitat. This measure of similar- 

 ity varies from to 1.0. The percentages by weight 

 of the major taxa (lower half of Table 4) were 

 identical at the three deepest (148-200 m) Sta- 

 tions: 2, 6, and 8. Stations 15 and 23, both located 

 at 102 m depth, were also very similar. Station 7 at 

 100 m was fairly similar ( C^^ > 0.87) to Stations 2, 

 6, and 8 located in deeper water. The percent of 

 major taxa in the diet of Dover sole at the shallow, 

 sand location (Station 22) was not very similar to 

 any other station (C^^O.58). 



The frequency of occurrence of principal prey of 

 Dover sole (Table 5) indicates fairly low similarity 

 among different stations for species of 

 polychaetes. Most species occurred at only one or 

 two stations and the assemblage of polychaetes 

 eaten by Dover sole appears to be different at each 

 station. As one would expect, similarity is higher 

 when higher taxa such as gammarid amphipods or 

 pelecypods are considered as a group. For this 

 reason comparisons of similarity among stations 

 should be confined to prey identified to the same 

 taxonomic level. 



To examine differences in prey species among 

 stations we calculated the overlap in diet (Cj 

 based on polychaetes alone, the most common and 

 speciose prey animals of Dover sole (and the food 

 gi-oup that one of us (Hancock) was familiar with 

 taxonomically). The range in overlap of diets 

 based on frequency of occurrence of individual 

 taxa of polychaetes at these stations (Table 5) was 

 appreciably lower than that based on weight per- 

 centage of major taxa (upper half of Table 4). Sta- 

 tions 2, 6, and 8, which were very similar on the 

 basis of the weight of major taxa in the Dover sole 

 stomachs, overlapped only moderately on the 

 basis of frequency of occurrence of polychaetes ( C^^ 

 = 0.37 - 0.45). Stations 15 and 23, similarly based 

 on major taxa, were the most similar iC , = 0.64) 

 stations based on frequency of occurrence of 

 polychaetes. Station 23 was the next highest in 



similarity with Stations 7 and 15. Thus, the 

 polychaete prey of Dover sole were most similar 

 among these three 100-102 m stations. 



Because stomachs of the other flounders were 

 examined for only two or three stations, few sta- 

 tion comparisons could be made. As with Dover 

 sole, the percentage of major taxa in the diets of 

 rex sole at Stations 2, 6, and 7 were similar, and 

 food habits were almost identical at Stations 2 and 



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