descriptions of various types of this gear, and Niska-Zgives a 

 detailed account of the construction and cost of the particular 

 gear used by POFI, For these reasons only a brief description 

 is given in this report„ 



The basic unit of longline gear is the "basket," It is 

 similar in significance to the term "skate" used in the Pacific 

 halibut fishery. Originally it meant the amount of line that could 

 be conveniently stored in the type of basket shovm in figure 3, 

 A "basket" consists of a length of main line to -which a number of 

 branch lines, usually five or six, are attached at intervals. Each 

 branch line is made up of a cotton section (of the same material as 

 the main line), a sekiyama (also known as " s hanawa" ) section, and 

 a wire leader to which a 9/0 or similar hook is attached. 



The line currently used by POFI is designed to duplicate 

 commercial gear in catching efficiency and at the sajne time furnish 

 data suited to statistical analysis. During the course of its 

 development the gear underwent several modifications (fig. 4), 

 leading to the type first used on Snii th Cruise 11, This gear has 

 several operational advantages. It is easy to construct because of 

 uniformity of the component parts of each basket ^ and this also 

 simplifies replacement of worn out or broken parts during fishing. 

 In addition, the amount of tangling of the branch lines is minimal 

 because the distance between branch lines is more than twice their 

 combined lengths. 



Fishing at deep levels with the " Smith Cruise 11" gear is 

 accomplished by setting the main line slack so it will sag. This 

 sag should take the form of a catenary, and the cuimres in figure 5 

 are based on this assumption. As shown in figure 5, a wide range 

 of theoretical or potential hook depths can be achieved by simply 

 altering the distance between buoys when the gear is set. The actual 

 depth attained by the hooks is, of course, also dependent on such 

 factors as currents, which may cause the line to stream out. 



The baits generally used by POFI were frozen sardines 

 ( Sardinops caerulea ) obtained from California, The most suitable 

 size is three or four to the pound. Before use they were thawed 

 and packed in rock salt for about 3 days. This increased their 

 firmness and retarded decom.position. As the line was set the baits 

 were attached by hooking them through the eyeSo 



The daily fishing operation usually commenced at dawn with 

 the setting of the gear. This operation took from 45 to 90 seconds 

 per basket depending on the crew involved, the speed of the vessel. 



-/ Niska, Edwin, MS, Construction details of tuna longline gear 

 used by the Pacific Oceanic Fishery Investigationso 



