272 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 1. — Number of hauls, cruises, and general areas xchere nildwater trawling was accomplished, by type of gear, 



central Pacific, 1951-56 



SOURCE OF DATA 



This report is concerned with the results of 274 

 michvater trawl hauls made on 22 cruises of 

 Bureau of Commercial Fisheries vessels in the 

 central Pacific during the years 1951-56. A sum- 

 mary of the hauls made and the general areas 

 sampled by each vessel on each cruise is given in 

 table 1. Positions of the trawl stations are sup- 

 plied in appendix tables 1 to 4. 



The area investigated extended from latitude 

 49° N. to 19° S. and from longitude 108° W. to 

 162° E. The approximate positions of stations 

 where each type of trawl was employed are shown 

 in figures 1 to 4. 



DESCRIPTION OF GEAR AND METHODS 

 OF HAULING 



This report is concerned with the results ob- 

 tained with four kinds of trawls: (1) 6-foot beam 

 trawl, (2) 1-meter ring trawl, (3) 6-foot Isaacs- 

 Kidd trawl, and (4) 10-foot Isaacs-Kidd trawl. 

 A description of each trawl follows. 



6- FOOT BEAM TRAWL 



This trawl consists of a net 30 feet in length with 

 a 6-foot-square mouth opening held open across 

 the top and bottom by 6-foot lengths of galvanized 

 pipe (fig. 5). The body of the net is constructed 

 of 1-inch (stretched measure) cotton netting; the 

 cod end is of i^-inch mesh. The I'ear half of the 

 net, including the cod end, is lined with 3/16 mesh 

 (square measure) minnow netting. We do not 

 know where the design for this gear originated. 



This trawl was operated from the John R. Man- 

 ning and the Hugh M. Smith at speeds of 4 to 5 

 knots, using a towing cable of i4"ii^ch wire rope. 

 On each haul a 50-pound bronze depressor or a 

 100-pound streamlined lead weight was suspended 

 from the lower pipe beam. Table 2 gives the min- 

 imum and maximum towing tensions obtained 

 when hauling at various speeds and with different 

 amounts of wire out. At the usual hauling speed 

 (4 to 5 knots) the maximum tension did not ex- 

 ceed 2,000 pounds. Most hauls were oblique 

 tows, ranging from tlie surface to depths as great 

 as 450 meters. Tl\e depth of the haul was esti- 



