separate the soft tissue. After drying, the otoliths 

 (sagittae) and other distinctive bones were picked 

 out by hand. The bones were identified by com- 

 parison with material from fish specimens collected 

 from both the Atlantic and Pacific Oceans by mid- 

 water trawling. 



RESULTS 



The first stomach contained about 1 1 of material, 

 nearly half of which was partially digested squid 

 flesh; a roughly comparable portion was composed of 

 fish bones. Fish muscle, squid beaks, and shrimp 

 remains made up the small remainder. The second 

 stomach's 2 1 volume was roughly 90% fish bones, 

 with small amounts of squid and fish flesh, shrimp 

 carapaces, and squid beaks. No soft tissue remained 

 in the third stomach; the volume of its contents was 

 only about 0.125 1, and 90% of this was composed of 

 shrimp exoskeletons. The remaining volume was due 

 to fish bones, squid beaks, and eye lenses. Fish had 

 clearly been the dominant component of the diets of 

 all three Fraser's dolphins. 



The three stomachs yielded 2,918 otoliths plus 

 several hundred identifiable dentary, opercular, and 

 cleithral bones. Table 1 presents the otolith data and 

 the identities of the fishes they represent. An account 

 of the most abundant fishes follows. Stomiatoid 

 genera are classified according to Weitzman 

 (1974). 



Gonostomatidae 



Otoliths of the genus Gonostoma are highly distinc- 

 tive and easily discerned among stomach contents. 

 The Gonostoma otoliths and dentary bones from the 

 L. hosei stomachs are probably all from G. elongatum. 

 We estimated the size of the fishes by comparing 

 their dentary bones with those from specimens of G. 

 elongatum which were collected by midwater trawl- 

 ing gear, albeit from Atlantic populations. The range 

 of estimated standard lengths, 83 to 225 mm, shows 

 that many of those ingested by the dolphins were 

 quite large by trawl-sample standards (see Backus et 

 al. 1965, 1969; Clarke 1974). 



Sternoptychidae 



Two sternoptychid genera were present in all three 

 stomachs. Most of the A rgyropelecus otoliths can be 

 assigned with confidence to A. lychnus, while the 

 remainder are probably from A. affinis. These 

 hatchetfish occupy limited depth horizons both day 

 and night and are common forage of large pelagic 



FISHERY BULLETIN: VOL. 81, NO. 2 



animals. Our size estimates are based on the length of 

 cleithra from the dolphin stomachs compared with 

 those from specimens of A. lychnus trawled in the 

 eastern South Pacific and on comparisons of otoliths 

 with trawl-caught A. lychnus from the eastern North 

 Pacific. Both methods indicated that the dolphins 

 had been feeding on a size range of about 40 to 70 

 mm. Here again the larger specimens ingested byL. 

 hosei exceed the size of those commonly collected by 

 trawling (Baird 1971). 



Among the sternoptychid otoliths found in the 

 dolphin stomachs, we are least certain of those 

 tentatively designated iMaurolicus muellerp. in Table 

 1. While this species is worldwide in distribution, and 

 the sagittae resemble slightly digested versions of 

 those from trawled Atlantic specimens, some uncer- 

 tainty remains. 



Photichthyidae 



The examples of Ichthyococcus reported here are 

 most likely from /. irregularis, which inhabits the 

 eastern Pacific region where the three Fraser's 

 dolphins were captured (Rechnitzer and Bohlke 

 1958). The peculiar configuration of Ichthyococcus 

 otoliths is such that their fragile anterior projections 

 are easily broken or dissolved, thus precluding ac- 

 curate otolith length measurements. In this case we 

 have used otolith heights for our estimates of fish 

 size. When plotted on an otolith height vs. standard 

 length curve for/, irregularis from the eastern Pacific, 

 the otolith heights of these specimens suggest that the 

 individuals caught by the dolphins ranged from 40 to 

 69 mm (Fig. 1). The largest otoliths from the dolphin 

 stomachs are at the upper size limit of those available 

 for comparison from trawl collections. 



Chauliodontidae 



Chauliodus otoliths and dentary bones were pre- 

 sent in all three dolphin stomachs. We estimate the 

 average standard length at about 180 mm, based on 

 dentary length. These fishes have wide vertical 

 ranges and exhibit irregular patterns of diel migra- 

 tion. Their movements appear to be related to their 

 role as predator of vertically mobile gonostomatids, 

 sternoptychids, and myctophids. Among the species 

 which inhabit the eastern Pacific, it is most likely that 

 the abundant remains attributable to this genus are 

 from C. barbatus. 



Paralepididae 



Adult barracudina otoliths were present in all three 



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