A standard model of a midwater trav/l — sometimes called 

 "Phantom" trawl — ^^-rith vertical and horizontel spreads of I48 to 52 feet, 

 and a smaller net with a 36-to 38-fcot opening were tested by the United 

 States Fish and U'ildlife Service M/V Oregon (Springer and Bullis, 19^2), 

 The standard size net was too large to maneuver properly with the poxjer 

 availiable. Better results, because of higher trawling speeds and better 

 maneuverability, v:ere attained vjith a smaller model. During these tests 

 no indication of the effectiveness of the midwater trawl fishing for 

 shrimp was obtained. 



Trawl Doors . — ^The trawling doors are constructed of wood, us- 

 ually hard pine, •with iron fittings. The bottom of the doors are equipped 

 with iron runners. Their size varies in accordance with tne towing pow- 

 er of tne vessel, the depth of the water and the size of the net. The 

 doors serve to hold the mouth of the net open when towing and are fas- 

 tened to the four corners of the mouth with manila-clad cable. The 

 proper rigging of the doors and net leads involves careful adjustment, 

 and the success of the fishing operation is largely dependent upon the 

 experience of the captain in making these settings. A mistaJce in rig- 

 ging the doors can result in collapsing the spread of the net and in 

 towing it too low or too high. 



Trawling doors of I4. to 5 feet in length are nsed on travjls 

 up to 5^ feet in width, 6-to 8-foot doors on trawls up to 80 feet, and 

 9-to iU-foot doors on nets up to 120 feet wide. The doors are set ac- 

 cording to individual preference. They can be purchased completely 

 rigged. 



\<lhen in deep water, the doors are weighted with iron bars 

 bolted Just above the runner. In this manner 5-foot trawl doors, each 

 weighted with a 100 pound bar, have been used successfully while fishing 

 in over U50 fathoms. (Bullis, 19^1) 



Tr awling Cables . — Trawling cables are usually 7/16-to l/iJ- 

 inch steel stranded wire. From 125 to 150 fathoms of cables are usually 

 wound on each spool. The cable leng-th-depth ratio should be 5-6 fathoms 

 of line to 1 fathom of water depth to assure full spread of the trawl. 

 In deeper x>jaters a 2:1 ratio has been employed successfully. (Bullis, 1951) 



Cables must be replaced about twice a year. Springer (1955) 

 recommends tne use of galvanized preformed cable, which e:cperience 

 aDoard the M/V Oregon has shown to be superior. 



Hanging Line,— An experienced net maker in Texas recommends 

 the use of a stainless steel manila-clad line for the hanging of the 

 net. Such a line apparently lasts twice as long and costs only 50 per- 

 cent more than regular manila-clad steel cable. An additional advantage 

 is that the stainless steel cable can be spliced if a break occurs in 

 the leadline section. This, reportedly, cannot be easily done with the 

 regular manila-clad steel cable, which corrodes. 



88 



