FISHERY BULLETIN: VOL 79. NO. 4 



In the tropics, swordfish undergo daily vertical 

 migrations, rising to feed near the surface at night 

 and returning to deeper waters by day ( Beardsley 

 1978). The full extent of these vertical migrations 

 is poorly known. Cephalopods also exhibit vertical 

 distributions and diel migrations of considerable 

 range (Voss 1967; Clarke and Lu 1974, 1975; Lu 

 and Clark 1975a, b; Roper and Young 1975; 

 Herring 1977). While these works provide 

 some data on bathymetric distribution suggesting 

 general patterns of vertical migration, the actual 

 distributions of most cephalopod species remain 

 poorly known. At the familial level, all but three of 

 the cephalopods encountered in this work may 

 occur from the surface to depths between 500 and 

 1,000 m. Histioteuthids are found from near the 

 surface to about 2,500 m. Cranchiids range, in 

 general, from the surface to about 3,000 m, but 

 the only species found in swordfish stomachs, 

 Cranchia scahra, is confined to the upper several 

 hundred meters of the water column (N. Voss"*). 

 Thore (1949) stated that adults of Japetella dia- 

 phana are found in 330-3,000 m of water, while 

 younger animals are concentrated at depths of 

 100-330 m. Bathymetric ranges of all cephalopod 

 species considered here encompass the upper 

 500 m of water. While it remains possible that 

 swordfish forage at greater depths, it appears that 

 most feeding is concentrated in epipelagic and 

 upper mesopelagic waters. 



This analysis of the cephalopod component of 

 the swordfish diet supports earlier observations 

 (Scott and Tibbo 1968), suggesting the opportu- 

 nistic nature of X. gladius predation. Based on 

 the data presented here, prey composition is 

 independent of season, fish size, or sex. Rather, 

 stomach contents appear to reflect the diversity 

 and relative abundance of potential prey. 



Voss (1953) examined stomach contents of 241 

 sailfish, Istiophorus americanus ( = /. platy- 

 pterus), from Florida waters. Of 461 identified 

 prey, 83'7f were fish, including members of at least 

 20 families. A total of 78 cephalopods, including 27 

 octopods, were found. Voss identified the octopod 

 specimens as Argonauta argo, Argonauta sp., and 

 Grimpoteuthis?. Of the 49 teuthoids recovered, 

 all were considered Sthenoteuthis bartrami 

 {= Ommastrephes bartrami), but probably 

 were O. pteropus. Maksimov (1971) examined 



stomachs of sailfish from the tropical Atlantic. 

 Teuthoids and octopods predominated as 

 food. Over 61% of sailfish stomachs from Brazil 

 contained squid and 50% contained octopods. Sail- 

 fish taken off Barbados contained squid, but no 

 octopods. Jolley (1977) examined 778 sailfish from 

 off southeast Florida and found scombrid fish to be 

 the most important prey followed by cephalopods. 

 Jolley found 27% of all stomachs examined to be 

 empty. 



Krumholz and de Sylva (1958) reported on the 

 stomach contents of white marlin, Tetrapterus 

 albidus, taken near Bimini, Bahamas. Nine 

 stomachs contained cephalopods, arthropods, and 

 fish. Squid and octopods were the most abundant 

 items, accounting for 41% and 18%, respectively, 

 by frequency of occurrence. An additional 41 

 stomachs were empty. De Sylva and Davis (1963) 

 examined stomachs of 55 white marlin from the 

 Middle Atlantic Bight. Round herring, Etrumeus 

 teres, and Loligo pealei were the chief components 

 of the diet. Ovchinnikov (1970) investigated diets 

 of white marlin in the tropical Atlantic, noting 

 Loligo pealei as the most important prey. 



Krumholz and de Sylva (1958) also reported on 

 14 blue marlin stomachs of which 10 contained 

 food. Fish were more important than cephalopods 

 by frequency of occurrence. Cephalopod remains 

 consisted of the pelagic octopods Argonauta argo 

 and Ocythoe tuberculata, which together consti- 

 tuted 17% of the total number of prey. Voss and 

 Erdman (1959) reported finding a large specimen 

 of the squid Thysanoteuthis rhombus in the stom- 

 ach of a blue marlin caugnt off San Juan, Puerto 

 Rico. Ovchinnikov (1970) investigated stomachs 

 of blue marlin. These fish contained teuthoids 

 and less frequently sepioids. Fish were more 

 important than cephalopods in the diet of blue 

 marlin. 



Two observations are apparent from compar- 

 isons of diets of istiophorids and swordfish. First, 

 fish appear to be more important in diets 

 of istiophorids, with cephalopods of secondary 

 importance. The opposite is true for swordfish. 

 Second, octopods may be a more important com- 

 ponent of the cephalopod prey of istiophorids than 

 of swordfish. 



ACKNOWLEDGMENTS 



"N. Voss, Division of Biology and Living Resources, Rosenstiel 

 School of Marine and Atmospheric Science, 4600 Rickenbacker 

 Cau.seway, Miami, FL 33149, pers. commun. July 1980. 



The authors wish to thank Steven Berkeley, 

 Lise Dowd, and Mark Poll for assistance in the col- 

 lection of specimens. Berkeley also provided data 



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