FOOD OF ALBACORE IN THE PACIFIC 



461 



fisliin": loiiffliiie. Len<^h frequency distribuHoiis 

 of the albacore from which stomachs were col- 

 lected are shown in figure 2. 



METHODS 



The stomachs were removed as soon as possible 

 after the albacore came aboard, but the time inter- 

 val between the moment of capture by the fishing 

 gear and removal of the stomach varied consider- 

 ably. Stomachs of troll-caught fish were removed 

 immediately after capture, while the stomachs of 

 some fish caught by longline or gill net were un- 

 doubtedly not removed until several hours had 

 elapsed between the hooking or gilling of the fish 

 and the hauling of the gear. 



Of the 544 stomachs examined, the contents of 

 196 were analyzed at sea during John R. Mannmg 

 ci'uise 36. This analysis consisted of measuring 

 the total displacement volume (^ 5cc.) of each 

 stomach's contents and recording the numbers or 

 presence of the following food groups: squid, 

 saury {Cololahis sp.), other fish, shrimp-like 

 plankton, copepod-amphipod-like plankton, and 

 unidentifiable remains. 



The other 348 stomachs were preserved for ex- 

 amination in the laboratory by placing tliem in 

 muslin bags, along with any regurgitated material 



ao" 



-M^,4^i-A 





-longljw 



- tuclujg 



- W.L NET 



rr 



l''i(;ii<K 1. — I^ocatiiuis wliciv sluiiiiK li saiiiiilcs ucic InUcii 

 from albacore captnrocl b.v loiifjliiie, jl;!!! net, and troll- 

 ing in the c-entral and nortlicMstern I'McHic, 1'J.50-.j7. 



LONGLINE CAUGHT 



s  lei* 



ALL METHODS COMBINED 



H • M2 



n 



^^^r^U> - 



FORK LENGTH (CENTIMETERS) 



APPROXIMATE WEIGHT (P0UW6) 



FiGiBE 2. — Length frequency distributions of albacore 

 tuna from which stomachs were collected. (Asteri.sk 

 indicates one sliarl<-iiintilated specimen not included.) 



recovered, in 10 percent formalin. Collection data, 

 including ves.sel, cruise number, locality, date, fork 

 length, time of capture if known, method of cap- 

 ture, bait species, and the observer's initials, were 

 recorded on a cloth label which was placed in the 

 muslin bag with the stomach. 



In the laboratory the stomachs were soaked 

 overnight in fresh water to remove excess forma- 

 lin. The stomachs were then opened and the var- 

 ious food organisms separated according to 

 species or to whatever taxon the precision of 

 identification permitted. The number of mdi- 

 viduals in each species or group was counted, and 

 their volume determined hy the displacement of 

 water in a graduated cylinder. Bait found in 

 the stomachs of longline-caught albacore was 

 excluded. 



A checklist of food organisms from 348 

 stomachs analyzed in the laboratory appears in 

 the Appendix table. The contents of the 196 alba- 

 core stomachs analyzed at sea have been reported 

 by Graham (1959). In a number of instances the 

 data obtained from these two groups of stomachs 

 could not be analyzed together due to tiie ditl'or- 

 ences in the method of recording data. 



Stomaclis were randomh- selected except on 

 John R. Manning cruise 36, when 48 stomachs 



