CENTRAL NORTH PACIFIC ALBACORE SURVEYS, 

 MAY TO NOVEMBER 1955 



By 



Joseph J. Graham 



Fishery Research Biologist 



Pacific Oceanic Fishery Investigations 



Honolulu, T, H, 



The Pacific Oceanic Fishery Investigations 

 (POFI) of the U. S. Fish and Wildlife Service is 

 conducting a comprehensive study of the resources 

 of the albacore tuna, Germo alalunga (Bonnaterre), 

 north and northeast of the Hawaiian Islands under 

 Public Laws 329 and 466 (the latter known as the 

 Saltonstall-Kennedy Act). This investigation is 

 primarily concerned with the distribution and 

 abundance of albacore with a view to comnner- 

 cial exploitation and is supported by biological 

 and oceanographic studies. To date, 11 cruises, 

 8 exploratory fishing and 3 oceanographic, have 

 been completed; the results of 6 of these cruises 

 in 1954-55 have been described (Shomura and 

 Otsu 1956). This report will deal primarily 

 with the fishing results obtainedfrom the remain- 

 ing 5 cruises completed during 1955. The general 

 cruise periods and areas of operation are given 

 in table 1 . 



The 5 cruises were undertaken by the 

 research vessels Hugh M. Smith, John R. 

 Manning , and Charles H. Gilbert under the 

 conrimajid of Barnes CoUinson, Fred E.Barnett, 

 and William T. Tanaka respectively. The sci- 

 entific data were collected by or under the 

 direction of Field Party Chiefs Richard S. 

 Shomura (Smith 29 and Gilbert 23), Tamio Otsu 

 ( Manning 26), Wilvan G. Van Campen ( Manning 

 25), and James W. McGary ( Smith 30). I wish 

 to acknowledge the sincere efforts of the captains, 

 crews, and scientists in making these data 

 available. 



The area under investigation by POFI 

 lies between two important North Pacific alba- 

 core fisheries. The Japanese longline fishery 

 extends fronn the coast of Japan to the vicinity 



of Midway Islamd (Suda 1954) and fishes for deep- 

 swimming albacore. The North American troll- 

 ing fishery has its nucleus along the coast of 

 southern California (Clemens 1955) and fishes 

 for surface-swimming albacore. To insure 

 adequate vertical as well as horizontal sampling 

 of albacore in the area between these two fish- 

 eries, POFI has ennployed b ot h longlinea and 

 surface trolling gear. Surface gill netting has 

 also been undertaken to a limited extent. 



MATERIALS AND METHODS 



A detailed description of POFI albacore 

 longline gear has been presented by Mann (1955) 

 and Shomura and Otsu (1956). Briefly, the basic 

 unit, or "basket," of gear is composed of 210 

 fathoms of mainline to which floats are attached 

 at either end. Droppers 3 fathoms long are 

 suspended from this mainline at intervals of 15 

 fathoms. Wire leaders and hooks are attached 

 to the droppers. POFI longline sets during the 

 above cruises consisted of 40 baskets of gear, 

 with 13 hooks per basket. To secure a wide 

 vertical range over the entire horizontal range 

 of sampling, 5- and 15 -fathom floatlines were 

 alternated in groups of 10 baskets. The former 

 were set taut and the latter at normal slack. Sets 

 were made at daybreak (0500) and hauling com- 

 menced at noon. Setting required approximately 

 1 hour and hauling 3 to 4 hours, allowing a fish- 

 ing time of roughly 6 hours. 



The maximum depth fished by baskets 

 in several parts of the set and the symmetry of 

 individual baskets were measured by the use of 

 sounding tubes as described by Shomura and 



Table 1. --POFI cruises investigating albacore tuna resources in the North Pacific, 1955 



