TRAWLING FOR FORAGE ORGANISMS IN CENTRAL PACIFIC 



277 



of wire out. Depth conversion factor's (table 4) 

 were calculated from plots of these data. 



T.\nLE 4. — Depth conversion factors used to estimate depth 

 of haul for 6-foot Isaacs-Kidd trawl 



(Wire out (in meters) X factor = trawl depth (in meters)) 



1 Cosine of the wire angle, the appropriate conversion factor if the towing 

 wire described a straight line, is given for comparison. 



10- FOOT ISAACS-KIDD TRAWL 



Since the 10-foot trawl used in this study by 

 the Laboratory in Honolulu has been considerably 



modified from the oi-ijjinal plans given by Dever- 

 eaux and Wiiisett (1953), we shall provide a de- 

 tailed description of the main features of the 

 gear. 



Trawl Net 



A schematic view of the net is shown in figure 

 8 and detailed plans are given in figure 9. 



The front section of the net, about 27 feet in 

 length, is made of liA-inch mesh (stretched meas- 

 ure), double-knotted. No. 207 nylon twine, dyed 

 red. The mesh counts for tapering the top, bot- 

 tom, and side panels are shown in detail "A" (fig. 

 9). The headlines and other supporting lines are 

 of %-inch 3-strand nylon. The headline is 

 attached to the diving vane by wire pennants of 

 i/4-inch-diaineter 7 x 1!) stainless steel wire Xico- 



OF VANE AND NET 



Figure 8. — Schematic view of the 10-foot Isaacs-Kiild trawl used li.v the Bureau of Commercial Fisheries Biological 



Laboratory. Honolulu. 



