Williams 1988). During submersible dives at John- 

 ston Atoll, Ralston et al. (1986) verified this cohabi- 

 tation with visual observations of the two species. 

 PHstipomoides zonatus were observed between 215 

 and 250 m (median, 230 m) and P. auricilla between 

 205 and 295 m (median, 240 m). Our dietary anal- 

 ysis suggests that these two demersal species par- 

 tition food resources by selecting prey from differ- 

 ent microhabitats. Pristipomoides zonatus is best 

 described as a demersal carnivore, with its diet con- 

 taining benthic and demersal invertebrates together 

 with tunicates and small fishes. In contrast, P. 

 auricilla feeds primarily on large pelagic plankton, 

 as evidenced by the abundance of heteropods, 

 pteropods, and tunicates among the prey items. 



Kami (1973) also found tunicates {Pyrosoma spp.) 

 in four of the five P. auricilla food samples in Guam. 

 The differences in diet composition are consistent 

 with the suggestion, based upon catch rates and the 

 taking of a baited hook, that P. zonatus is the more 

 aggressive predator of the two species (Polovina 

 1986). 



Although our study revealed little overlap be- 

 tween the diets of P. zonatus and P. auricilla, the 

 common occurrence of Pyrosoma spp. in the diets 

 of both species seems significant. Similarly, these 

 tunicates were also found among the stomach con- 

 tents of three other congeneric species (Kami 1973; 

 Parrish 1987). Kashkina (1987) reported intensive 

 predation on pyrosomes, as well as salps, among 



Table 1.— Diet composition of Pristipomoides zonatus and P. auricilla at Pathfinder Reef, 



f^/lariana Archiipelago. 



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