274 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Figure 4. — Location of the 157 stations where hauls were made with the 10-foot Isaacs-Kidd trawl. 



1-METER RING TRAWL 



This gear, which we termed a "ring trawl," con- 

 sists of a circular net, 1-meter in mouth diameter 

 and 41/2 meters in length, attached to a steel ring 

 1-meter in diameter (fig. 6). The net is of 2-inch 

 mesh (stretched measure) No. 12 cotton twine and 

 is equipped with a cod-end liner of %6"i'^ch mesh 

 (square measure) minnow netting. On most hauls 

 an additional liner, slightly more than 1 meter in 

 length and of i^-inch mesh (stretched measure) 

 cotton netting, was attached in the net just for- 

 ward of the cod end. 



Except for one haul tliis gear was operated only 

 from the Charles H. Gilbert, usually at speeds of 

 6 to 7 knots, but reaching a maximum of 81/2 knots 



on a few test hauls. The towing cable was 14-inch 

 diameter wire rope. The 1-meter ring at the 

 mouth of the net was initially constructed of 

 %-inch stock and was without reinforcement. 

 At liigher towing speeds the ring did not retain 

 its shape and was replaced with one of 1-inch 

 thickness, reinforced with two transverse bars 

 (fig. 6). 



A 5()-pound depressor or a 100-pound stream- 

 lined weiglit was suspended below the net. At 

 average towing speeds (6 to 7 knots), the maxi- 

 mum towing tension did not exceed 1,000 pounds 

 (table 3). The trawl was operated, usually on 

 oblique tows, at depths ranging fi-om the surface 

 to 200 meters. As in the case of the 6-foot beam 

 trawl, the depth of haul was calculated trigono- 



