470 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



dertaken only for tlie fish captured in the equato- 

 rial Pacific. Results are shown in figure 14. 

 Samples from the temperate North Pacific were 

 not included because: (1) no stomachs were col- 

 lected from fish captured in the categories 0-24 

 and 25-99 miles from land, and (2) the fish from 

 which stomachs were collected in the temperate 

 North Pacific were much smaller, on the average, 

 than fish captured in the equatorial Pacific. 



SQUID 

 FISH 



(6) 



(8) 



(47) 



I 



 





^ 



(81) 



I 



I 



i 



i 



^ 



25-99 

 MILES FROM NEAREST EMERGENT LAND 



'Figure 14. — Variation in food of 142 albaeore captured 

 by longline in the equatorial Pacific, according to dis- 

 tance from nearest emergent land. (Numbers in 

 parentheses refer to sample sizes.) 



Although two of the categories of figure 14 (0- 

 24 miles and >400 miles) are based on small sam- 

 ples, the indication is that consumption of squid 

 increases in an offshore direction. The percent 

 occurrence of squid was as follows : 0-24 miles, 64 

 percent; 25-99 miles, 94 percent; 100-399 miles, 

 95 percent; >400 miles, 83 percent. King and 

 Ikehara (1956) found generally similar results 

 for the volume and percent occun-ence of squid in 

 the stomach contents of longline-eaught bigeye in 

 the equatorial Pacific, although they had no sam- 

 ples in the 0-24 miles category. This may reflect 

 an offshore increase in the abundance of the deeper 

 swimming squids in this area. The consumption 

 of fish was highest in the 0-24 miles category, with 

 lower, fluctuating values noted as distance in- 

 creased away from land. 



The appearance of reef-associated organisms in 

 the diet of equatorial albaeore, as might be ex- 

 pected, reflects the distance from land at the place 

 of the albacore's capture. Their appearance is 



summarized in table 5. The indication is that 

 fewer reef-associated organisms are eaten by alba- 

 eore as distance increases offshore, presumably a 

 reflection of the diminishing abundance of such 

 organisms. This is further evidence that albaeore 

 are opportunistic feeders, taking whatever prey is 

 available within broad food categories, an opinion 

 expressed by several other writers on the subject. 



T\Bi.E 5. — Percent occurrence of rerf-nssociateil organisms 

 found in the stonmcli contents of ajhacorc captured on 

 longline in the equatorial Pacific, according to distance 

 from nearest emergent land 



Organism 



Crustacea: 



Larval Stomatopoda 



Crab megaJopa ___ - 



Phyllosoma 



Homaridae — _ --- 



Fnoplometopus sp., postlarvae. 



Pallnurldae,' postlarvae _- 



Scyllaridae,' postlarvae 



Fish: 



Synodontldae ' 



Holocentridae ' - 



Holocenttus sp _ 



Apogonidae _ 



Cheilodipterus sp 



Carangldae 1 - 



Chaetodontldae ' 



Acanthuridae i 



Scorpaenidae ' __ -- 



Scorpaena sp _ 



Ballstidae ' 



Ostraciontidae i 



Lactoria diaphanus 



Tetraodontidae ' _-_ -- 



Number of stomachs examined. 



Miles from nearest land 



0-24 26-99 100-399 >400 



17 



'17 



6 



1 Unidentified. 



VARIATION IN FOOD WITH TIME OF DAY 



In order to examine the trend of feeding 

 throughout the day, stomach volumes of albaeore 

 caught by trolling during five summer cruises in 

 the temperate North Pacific were combined and 

 plotted by 2-hour pei-iods corresponding to the 

 local zone time when the albaeore were captured. 

 Results are shown in figure 15. Stomachs from 

 longline-eaught albaeore were not included, since 

 the exact time of their capture could not be deter- 

 mined. Stomachs examined in the field during 

 John R. Manning cruise 36 were included to in- 

 crease the sample size. Forty percent of these 

 field-examined stomachs were designated empty, 

 since only values of 5 cc. or larger were recorded 

 in the field. However, since figure 4 shows that 34 

 percent of all laboratory-examined stomachs had 

 volumes less than 1 cc, a percentage reasonably 

 close to the 40 percent of the field-examined stom- 

 achs designated empty, these stomachs were 

 included. 



