Net frames, 1.2 by 2.4 m, were constructed 

 of 3-mm flat steel reinforced with 6-mni iron 

 rods. Six U-bolts were welded to the frame for 

 the attachment of stainless steel cables which 

 bridled each frame to a double block bolted to 

 the end of each outrigger. The trash screens 

 were made of 6.4-cm square mesh galvanized 

 hardware cloth soldered onto galvanized metal 

 frames which were bolted to the net frame. The 

 nets were fabricated from nylon netting (169 

 meshes per square inch) measuring 3.7 m in 

 length and patterned so that the seams ran from 

 the corners of the metal frame to the aluminum 

 rings. The rings were attached with bayonet 

 fittings to the collecting funnels. Both the mouth 

 and tail of the nets were reinforced with cotton 

 duck and fitted with brass grommets so that the 

 nets could be laced on the frames and rings. 



The collecting funnels were made with 3-mm 

 flat stock aluminum and were 90 cm long (30 

 cm outside diameter at the mouth and 7.5 cm 

 inside diameter at the tail). A 15-cm nipple 

 was welded to the posterior end where the suc- 

 tion hose from the pump was attached, and a 

 10-cm flat band was welded to the mouth of the 

 funnel. L-shaped slots were cut in the leading 

 edge of the band. These slots were spaced so 



that countersunk bolts in the aluminum ring of 

 the net could be inserted and rotated for quick 

 attachment of the net to the funnel. 



The self-priming, centrifugal, solids handling 

 pump ("Crown" model P03LB, Construction 

 Machinery Company, Waterloo, Iowa") was 

 powered by the winch power shaft (Figure 3). 

 In turn, the power shaft was controlled by a 

 small hydraulic motor which allowed regulation 

 of pumping speed. Water volume output could 

 be controlled from to 180 gal/min. 



The pump intake pipe was attached to a 7.6- 

 cm (outside diameter) PVC (polyvinyl chlor- 

 ide) tee. A reinforced rubber hose led from each 

 side of the tee to the respective funnel, and a 

 brass screw valve was incorporated in each hose 

 so that we could pump from either or both nets. 



The sorting box (Figures 3 and 4) was de- 

 signed so that the smallest animals caught would 

 be retained and the larger ones discarded. This 

 was accomplished by pumping the catch from 

 the nets onto three sets of sloping screens. A 

 water-jet system was used to keep the animals 



° Use of trade names in this publication does not imply 

 endorsement of commercial products by the National 

 Marine Fisheries Service. 



Figure 3. — Pump, sorting 

 box, and holding tank. 



1300 



