United States Department of the Interior, Oscar L. Chapman, SecretaiT- 

 Fish cuid Wildlife Service, Albert h. Day, Director 



Fishery Leaflet 402 



Washington 25, D. C. 



April 1952 



NORTH PACIFIC ALBACORE TUNA EXPLORATION~1950 

 By Donald E. Powell,* Dayton L. Alverson"^ and Robert Livingstone, Jr.* 



Contents 



Page 



Introduction • 4 



Background 4 



Objectives and Plan » 7 



Description of Gear sind Exploratory Fishing Methods 8 



Trolling Gear o 8 



Make-up and Specifications 8 



Trolling Methods and Lure Effectiveness 10 



Gill Nets 12 



Construction and Specifications o 14 



Setting and Hauling the Nets 14 



Long Line 17 



Make-up of Long Line o » » 17 



Setting and Hauling Long Line o 18 



Occurrence of Albacore and Fishing Results o 20 



Indicated Migration Pattern <> • 20 



Catches by Gear with Certain Related Hydrographic Aspects .» 23 



Troll Catches 00 23 



Gill-net Catches « 25 



Condition of Gill-net Fish .,„ « 28 



Vertical Distribution and Mesh Size o..o.> 29 



Long-line Cat ches , « 30 



Related Obs ervations o 30 



Size of Albacore 30 



Food of Albacore 33 



Tagging of Albacore c....c 34 



Water Temperatures c »»...« 35 



Surface Distribution 36 



Verticeil Distribution 46 



♦fishery methods and equipment specialist, exploratory fishing and gear development 

 section, branch of commercial fisheries, seattle, washington. 



