Figure I Billf ishes of the central Pacific Ocean 

 include (a) shortbill spearfish, (b) Pacific sailfish, 

 (c) block marlin , (d) blue marlin , (e) striped 

 martin, and (f) broadbill swordfish. (Drawings 

 adopted by permission from Gosline, William A , 

 and Vernon E Brock, " Handbook of Hawaiian 

 fishes," copyright I960 by the University of 

 Hawaii Press , fig 258 ) 



SQUID 8 CRUSTACEANS 

 DEEP-SEA FISH 

 UNIDENTIFIED FISH 

 DOLPHIN 



SMALL SURFACE FISH 



The broadbill swordfish is considered to be in a 

 family by itself (the Xiphiidae); the other billfishes 

 listed above are members of the family Istiophoridae. 

 Drawings of these species appear as figure 1. 



The blue marlin and the broadbill swordfish are 

 circumtropical, whereas the other species have more 

 restricted distributions. The striped and blue mar- 

 lins are common or abundant in the central Pacific, 

 the black marlin is uncommon; the Pacific sailfish, 

 broadbill swordfish, and shortbill spearfish are rare- 

 ly caught. 



Figure 2. Volumetric percentoge occurrence of 

 foods in the stomochs of 16 blue marlin caught 

 by trolling. 



The billfishes feed broadly on fish, squid, crusta- 

 ceans, and other foods available on the high seas. 

 Diets differ between the species as well as between 

 populations of the same species. The striped marlin 

 feeds on several fishes, including tuna, in the central 

 Pacific. Stomachs of blue marlin in the central Pa- 

 cific contain mostly tunalike fish (especially skipjack 

 tuna). Less is known about the food habits of the 

 black marlin. Specimens have been taken containing 

 ocean sunfish, skipjack, yellowfin, albacore, and big- 

 eye tuna. Squid seems to be the major food of central 

 Pacific sailfish and shortbill spearfish. 



In terms of volume, small tunas, such as skipjack 

 (aku), little tunny (kawakawa), frigate mackerel (keo- 

 keo), and young albacore (ahipalaha) are very impor- 

 tant in the diet of Hawaiian blue marlin (fig. 2). These 

 fish also eat small deep-dwelling squirrelfish (alaihi), 

 3-inch specimens of which have been seen in large 

 schools from a submarine at 600 feet depth. Billfish 

 probably forage regularly at considerable depth. 



Is the spear of billfishes used in feeding? Numer- 

 ous reports state that billfishes often stun their prey 

 with a slashing movement of the bill, then return to 

 seize and eat the stunned victim. Vernon E. Brock, 

 University of Hawaii, observed a billfish at the sur- 

 face of the water near Kona, Hawaii, with a dolphin 

 (fish) impaled on its bill. Observers aboard the 

 Bureau of Commercial Fisheries research vessel 

 Geronimo in the Atlantic Ocean also reported seeing 

 a dolphin impaled on the bill of a marlin. The marlin 

 splashed in an apparent attempt to dislodge the dol- 

 phin, then sounded and was not seen again. 



Tuna with apparent spearmarks on the body are 

 occasionally found in marlin stomachs. A 1,500- 



